Semester 1 Composite Longboard Critical Design Review

Critical Design Review

Fiber Reinforced Composite Long Board

submitted toBoardSport Technologies Enterprise

byComposite Longboard Team

Dept. of Mechanical Engineering – Engineering MechanicsDept. of Material Science and Engineering

College of EngineeringMichigan Technological University

1400 Townsend DriveHoughton, Michigan 49931-1295

Team MembersStephanie Haselhuhn

Austin O’ConnorStephen Olson

AdvisorDr. Ibrahim Miskioglu

December 12th 2014

William J. Endres, 10/04/07,

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Fiber Reinforced Composite Longboard

December 12th 2014

Executive Summary

In the world of board sports, a growing trend is that of the longboard. Longboards essentially are

skateboards, however they differ in length, as well as other geometry. Longboards are made with

various materials depending on how the rider intends to the use the board. For the average college

student looking for a green method of transportation, it is desirable to have a lightweight longboard,

however commercial lightweight longboards come with large price tags.

It is the goal of the team to create lightweight, lower cost longboards that can withstand the rigors

of a college campus and typical riding scenarios. In order to determine the best combination of

materials for creating such a longboard, the team intends to test sample coupon layups of different

material combinations. Test samples will undergo four-point bend testing in accordance with ASTM

C393, as well as fatigue testing following a modified version of ASTM D7774. The results of these tests

should aid in the final selection of materials for the longboard.

For simplicity, the team has decided to create a longboard utilizing a sandwich style composite. All

composites will use the same epoxy, Super Sap CLM from Entropy Resins. Three materials were chosen

as candidates for the core layer of the sandwich composite. These materials are bamboo, Divinycell PVC

cross linked foam, and EPS foam. Three fibers were also chosen as candidates for the final board design.

These three fibers are high strength carbon fiber, aramid Kevlar 29 fiber, and S2-grade glass fibers.

At the completion of the current semester, the team is waiting for delivery of materials to make the

testing samples. Upon the start of the coming semester, the team aims to test all of the coupons, thus

determining the optimal combination of fiber and core to create a longboard. Once testing is complete,

the team will then begin designing the board and manufacture several before the conclusion of the

semester

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December 12th 2014

Table of Contents

Acknowledgements………………………………………………………………………………………………………………………………iv

1 Introduction…………………………………………………………………………………………………………………………………..……1

1.1 Project Overview………………………………………………………………………………………………………..…………1

1.2 Use Cases……………………………………………………………………………………………………………………………...2

1.3 Background…………………………………………………………………………………………………….....…………………2

2 Design Problem Analysis……………………………………………………………………………………………………………………..4

2.1 Chain of Stakeholder Needs………………………………………………………………………………………………….4

2.2 Design Requirements…………………………………………………………………………………………………………….5

2.2.1 Objectives……….…………………………………………………………………………………………………….5

2.2.2 Constraints…………………………………………………………………………………………………………….5

3 Design Summary………………………………………………………………………………………………………………………………….5

4 Design Decisions………………………………………………………………………………………………………………………………….6

4.1 Materials Selection Process………………….……………………………………………………………………………….6

4.2 Test Method Selection………………………………………………………………………………………………………….6

4.3 Design of Experiment…………………………………………………………………………………………………………….7

4.3.1 Hypotheses……………………………………………………………………………………………………………7

4.3.2 Format of D.O.E. ………………………………………………………………………………….……………….8

4.4 Ultrasonic Testing on Epoxy Resin……………………………………………………………………..………………….8

4.5 Final Concept………………………………………………………………………………………………….…………………….9

4.5.1 Composite Model………………………………………………………………………………………………….9

4.5.2 FEA Modeling……………………………………………………………………………………………..……….10

4.5.3 Primary Components and Rough Budget……………………………….…………………………….11

5 Term-I Work-Plan Status……………………………………………………………………………………………………………..…….12

5.1 Task Descriptions……………………………………………………………………..…………………………………..…….12

5.2 Timeline………………………………………………………………………………………………………………………..…….12

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6 Term-II Work-Plan………………………………………………………………..……………………………………………………..…….13

6.1 Task Descriptions…………………………………………………..……………………………………………………..…….13

6.2 Timeline………………………………………………………………..……………………………………………………..…….14

References………………………………………………………………..…………………………………………………………………..…….15

Appendix A – House of Quality………………………………………………………………..……………………………………..…….16

Appendix B – Selection and Design (CES Graphs) ………………………………………………………………….………..…….20

Appendix C – Composite Model Samples………………………………………………………………..………….…………..…….21

Appendix D – Gantt Chart………………………………………………………………..……………………………………………..…….32

Appendix E – Collected Data from Ultrasonic Testing……………………………………………………………………..…….33

Appendix F – Gauge R&R from Ultrasonic Testing…………………………………………………………………………..…….34

Appendix G – Standard Operating procedure for Ultrasonic Testing………………………………………..……..…….35

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Acknowledgements

We would like to thank the following for their assistance with this project:

Dr. Ibrahim Miskioglu of the Department of Mechanical Engineering – Engineering Mechanics at

Michigan Technological University for his guidance in the project, teaching us a crash course in

composite mechanics and classical lamination theory of composites, and for filling the role as our

advisor.

Dr. Paul Sanders of the Department of Materials Science and Engineering at Michigan Technological

University for additional guidance in the project, particularly in fulfilling requirements for two of our

team members to have an adequate design project for their Materials Science & Engineering majors.

Dr. Daniel Seguin of the Department of Materials Science and Engineering at Michigan Technological

University for helping us to define our project in its initial stages, as well as providing ideas and guidance

to help us overcome roadblocks.

Dr. Ed Laitila of the Department of Materials Science and Engineering at Michigan Technological

University for instruction on how to use Ultra Sonic testing to determine material properties of the

epoxy we chose to use.

Paul Fraley of the Department of Materials Science and Engineering at Michigan Technological

University for guidance in mechanical testing procedures.

The Department of Materials Science and Engineering for their generous donation allowing us to

continue our project.

The software package Cambridge Engineering Software Edupack 2014 for providing useful materials

selection tools and material properties

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1 Introduction

1.1 Project Overview

An increasing trend in outdoor sports is the long board. A long board is essentially a skateboard;

however, the geometry of the trucks are different, and the shape of the board is often more complex

than the average skateboard. These differences make the long board more ideal for cruising along

sidewalks, rolling down hills, and transporting riders around the local college campus. When purchasing

a long board, it is generally expected that the board will be durable (high fatigue strength), rigid (high

stiffness), and lightweight (low density) for ease of use and carrying between classes. Some of the

highest quality long boards are made of composites, but these often come with a large cost.

As a senior design project, we aim to design a high quality, low cost long board. Developing this

long board will consist of several phases, in which the first will be research. An extensive literature

search will be conducted, which includes material testing standards, popular processing methods, cost

effective matrix/fiber materials, material alternatives as defined by the Cambridge Engineering Software

(CES) package, and other relevant material research. The team plans on completing a House of Quality

(HOQ) for the project, which will determine the performance expected of the board and benchmark

against competitors. In addition, mechanics principles will be utilized for composite materials to

determine theoretical values of material/mechanical properties as defined by the HOQ. Finally, a Gantt

chart will be created, and updates will occur throughout the project as necessary.

The next phase will be the experiment phase. Testable, nontrivial hypotheses will be created

based upon the previously generated HOQ, and, along with the composite property calculations, applied

to the composite model. This model will exhibit the statics characteristics of the composite long board,

and will reinforce the results from the Finite Element Analysis (FEA) solver of the composite properties.

Both the composite modeling and FEA solutions should optimize and satisfy a large majority of the Full

Factorial Design of Experiment (DOE), which will be conducted with coupons at the end of the research

phase; hence, the remaining DOE will primarily consist of further material selection, such as fiber and

core types. A correlating Measurement System Analysis (MSA) will be conducted, with a Standard

Operation Procedure (SOP), Gage R & R, and proper calibration being successfully documented and

completed. All the samples, including the control specimen, may either be manufactured by the senior

design team, or donated by a long board company.

The third phase will involve designing the board itself. Aspects to be considered when designing

the board include (but are not limited to): length, shape, profile, ease of manufacture, additional inserts

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December 12th 2014

for the trucks, etc. The board’s physical features will also be analyzed using FEA to minimize failure and

ensure adequate performance before the board enters production.

The final phase of the project will be the physical manufacturing of the board. The details of this

phase will be determined as the experimentation and design phases are completed. This phase may also

include testing of the manufactured boards in a real world setting, as well as comparison with other

popular long boards

1.2 Use Cases

For the use cases of the project, after the user has purchased and obtained the composite

longboard they can use it for free riding, transportation, slalom, or downhill racing. Free riding is using a

longboard on a flat surface to perform tricks or grabs on the board. Transportation is using the

longboard to travel. Slalom is the act of weaving in and out of a line of obstacles. Finally, downhill racing

is going down hills as fast as possible while remaining in control of the board. Downhill racing is a

competitive sport that can be done based on timed runs or against other riders on the hill. In order to

achieve these function, the longboard will be focused on being low weight, durable in the long term,

having a high stiffness, and being cheaper than competitor’s longboards.

1.3 Backgroun d

Longboards are typically classified as an alternative to skateboarding, where the board is both

longer and wider than traditional skateboards. The length of these boards typically ranges from 24” to

80” [1], which allows an increase in geometry variety. These boards usually have a larger wheel base to

accommodate the large deck size utilized, which in turn allows for more stability and traction. Since

longboards usually have a slightly lower durometer value than traditional skateboards, these boards

allow smoother rides and transitions while performing turns.

Material selection is of primary concern when considering the construction of a longboard deck.

Aramid fibers (Kevlar), S-grade glass fibers, and carbon fiber (high strength) were selected among a

variety of materials based upon their elastic modulus, tensile strength, density, and price properties.

Aramid fibers provide excellent resistance to solvents with a large fatigue strength, but is reactive to

prolonged ultraviolet light exposure, and absorbs water (hydrophilic). [2] Glass fibers exhibit corrosion

resistance and large melting temperatures; however, these fibers depict generic properties in many

other categories. [3] Carbon fibers display incredible strength and stiffness to weight ratios, but carbon

fibers are extremely expensive and tend to fracture – fail suddenly and catastrophically. [4] A table of

basic fiber material properties are shown below:

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Table 1: Comparative Table of Fiber Material Properties

Fiber Material Properties

Carbon Fiber (High

Strength)

Aramid Fiber (Kevlar 29)

Glass Fiber (S-Grade)

Density (kg/m3) 1840 1440 2495

Elastic Modulus (MPa) 235000 71000 89500

Poisson's Ratio 0.105 0.36 0.22

Shear Modulus (MPa) 105000 1150 37000

Tensile Strength (MPa) 4650 3250 4750

Compression Strength (MPa) 4950 250 4500

Fatigue Strength (10^7, MPa) 3955 2750 4230

Alternatively, longitudinal/transverse bamboo plywood, polyvinyl chloride cross-linked foam

(Divinycell), and extruded polystyrene foam were chosen as the selected testing materials. These

materials were selected based upon their density, compression strength, elastic modulus, and price

properties. [5] The PVC cross-linked foam is commercially available in industry, and excels at

compression strength, durability, and fire resistance; however, it is a fairly heavy material. Extruded

polystyrene foam constitutes high stiffness and moisture resistance, as well as low cost and density;

nevertheless, many other properties, such as compression strength, are considerably low. [6] Bamboo

exhibited desirable values for the property selection criteria, but bamboo is the heaviest selected

material, and may benefit the least from fiber additions. [7] A table of basic core material properties are

displayed below:

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Table 2: Comparative Table of Core Material Properties

Core Material Properties

Bamboo Plywood Divinycell PVC

Cross Linked

Foam (DH 100)

EPS Foam

(SG .03)Longitudina

lTransverse

Density (kg/m3) 700 700 100 30

Elastic Modulus (MPa) 17500 1750 109.5 9.5

Poisson's Ratio 0.39 0.04 0.32 0.275

Shear Modulus (MPa) 1285 201 40 4.25

Tensile Strength (MPa) 240 37.5 2.75 0.39

Compression Strength (MPa) 80 70 1.7 0.225

Fatigue Strength (10^7, MPa) 34.3 10.735 1.36 0.35

2 Design Problem Analysis

The stakeholders for this project are casual longboard riders, completive longboard riders, the board

sports enterprise, and the senior design team. The longboard should be cheaper than similar competitor

longboards. The created longboard will also be low weight to enhance its performance. In order to

withstand the normal wear and tear of longboarding and last a satisfactory amount of time the

composite longboard will be durable. Finally, the designed longboard will be aesthetically pleasing to

attract buyers and maintain professionalism.

2.1 Chain of Stakeholder Needs

The chain of stakeholder needs was identified using multiple House of Quality documents. Each of

the individual documents focuses on a different comparison. These documents can be viewed in

Appendix A. In the modern world of longboarding the demand for higher performance longboards at a

competitive price increasing each year. In order to meet this demand we aim to provide a product that

meets all of our customer’s needs. Below is a list of the identified stakeholders needs with a brief

description.

Safety –that the longboard needs to be safe to operate

Cost –the longboard needs to be compatibly priced and affordable

Durability –The longboard needs to be durable and able to withstand normal wear and tear

for a reasonable amount of time

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Visually Appealing –The longboard needs to be visually appealing to attract buyers

Weight –The longboard needs to be at or below the weight of competitor’s boards

Ride-ability –The longboard needs to be able to function in an appropriate way for riding

Eco-Friendly –The longboards materials and manufacturing should be as eco-friendly as

possible to attract buyers and preserve the environment.

Buying Local –If possible as many materials should be bought local to support the local

economy and attract buyers.

2.2 Design Requirements

2.2.1Objectives

To design, build, and test a fiber reinforced composite longboard deck utilizing the newly

completed longboard press if possible. Also to incorporate the fields of Mechanical and Materials

Engineering.

2.2.2Constraints

The identified constraints for this project are the provided budget from BST, the two semesters

of time that we have to work on it, the machining and manufacturing capabilities available, the testing

equipment available for usage, and obtaining the materials we desire.

3 Design Summary

To conduct testing on the selected materials, a general full factorial design of experiment (DOE) will

be performed on the hypotheses created for both the core and fiber materials. This may potentially

decrease the number of tests required from a statistical perspective. Some interactions and main

effects between the core and fiber materials may not be statistically significant, which will reduce the

total number of runs per test; thus, the 27 total runs per test, computed by the multiplication of 3 fibers,

3 cores, and 3 samples per combination may contain combinations that will not impact the outcome of

the objective. The objective is that the selected testing materials must withstand an infinite fatigue life

of 1200 lbs. This incorporates a maximum rider weight of 300 lbs. and a liberal factor of safety of 4.

Currently, both 3-/4-point bending and fatigue testing plan to be performed on the materials to

determine the load at which failure occurs, and the number of cycles to failure, respectively. The 3-/4-

point bending test will be performed first, as to eradicate failed material combinations from the fatigue

testing. A measurement system analysis will be implemented and conducted to determine the accuracy

and precision of the measured data.

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4 Design Decisions

4.1 Material Selection Process

The process of choosing the selected materials and properties incorporates the House of Quality

(HOQ). Based upon the results of the HOQ and the team’s design criteria, the following properties were

found to have the largest impact on longboard performance: tensile strength (fiber), compressive

strength (core), stiffness, density, and price. The fiber tensile strength directly impacts the lifetime of

the board through the yield stress, and the compressive strength correlates with dimensional stability.

Meanwhile, stiffness ultimately corresponds to how the longboard rides, and the density relates to the

weight and ease of transporting the board. These properties were chosen from a selection method

consisting of the most popular properties for both fibers and cores, in regard to longboards. The desired

fiber criteria includes eco-friendly, lightest, best strength, water resistance, and price while the desired

core criteria consists of eco-friendly, lightest, ease of manufacture, best strength, stiffness, and price.

These categories were broken down further if necessary, and the major correlations between the

subcategories and main categories was recorded, which became the basis for the material selection

process.

Once completed, the team voted on the most important property categories given above, and

began to utilize the Cambridge Engineering Selector (CES) to compute the best material in the database

for each property category. Material limits and two-property graphs were utilized to reduce the number

of possible materials. Afterwards, a line of slope one (assuming a direct correlation between each

property) was placed on the generated graph, and was dragged in the direction of desirable properties

(i.e. maximized strength, minimized density). From this proposed method, a single material option

remains and is included within the selected testing materials. If, for two different property category

processes, the same material would be chosen again, the second best option would instead be chosen.

This expands the variety of materials to undergo testing, which allows for better material selection

analysis. Negative material behavior of high ranking materials (such as asbestos) was also considered.

Values for these materials were also gathered from the CES software until the team performs testing on

them.

4.2 Test Method Selection

For this first semester, our project has focused on the materials science aspect of the project. So we

have not modeled our final geometric design for the longboard and run FEA on it. This will come after

the sample coupons are tested. Our focus this semester has been on designing experiments that will

allow us to choose the best fiber and core combination from the selected materials. There will be 9 total

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combinations of the fibers and the cores. These will serve as our minimal investment prototypes. The

test methods that we are going to use will assess the performance of the combinations with a full

factorial designed experiment.

This will be achieved with two ASTM standardized tests. The first test will be a four point bend test

to failure. This test is specialized for sandwich composites. The second test will be a fatigue test that will

cycle the samples until failure which will be adapted for our purposes as advised by Paul Fraley. The

reason the fatigue test will be adapted is because the required fixtures for fatigue testing as specified in

the ASTM standard are not available. It would be a significant time invested to build the fixture, which is

not possible given our planned timeline. These tests will be performed at the start of the second

semester.

4.3 Design of Experiment

The objective is that the selected testing materials must withstand an infinite fatigue life of 1200

lbs. This incorporates a maximum rider weight of 300 lbs. and a liberal factor of safety of 4. Currently,

both 3-/4-point bending and fatigue testing plan to be performed on the materials to determine the

load at which failure occurs, and the number of cycles to failure, respectively. The 3-/4-point bending

test will be performed first, as to eradicate failed material combinations from the fatigue testing. A

measurement system analysis will be implemented and conducted to determine the accuracy and

precision of the measured data.

4.3.1Hypothesis

For each category of selected testing materials (fiber and core), a corresponding hypothesis was

generated, which allows the design of experiment (DOE) to be completed. The fiber hypothesis is

provided below:

If a long board is made with S-2 glass fibers as reinforcement, then it will display better

performance in fatigue testing because it has comparable tensile strength to the other selected

materials, and it exhibits superior fatigue strength. Additionally, since glass fibers consist of a silicate

network, a relatively low bond length is achieved that increases tensile strength while maintaining an

adequate linear expansion.

Since S-2 glass fibers exhibit similar strength values to popular alternatives, such as carbon fiber.

However, since the bond length of the silicate network, which constitutes the majority of the fiber is

longer than those formed by carbon atoms, the glass fibers elongate more, and thus have a larger

fatigue strength, than carbon fiber. [3] However, these silicon-oxygen bonds are shorter in length than

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both the nitrogen-oxygen and nitrogen-carbon bond lengths, which allow for a larger tensile strength.

Similarly, a core hypothesis was formulated for the core hypothesis, which is displayed below:

If a long board is made with a bamboo core, then it will display better performance in testing

because the core will provide a similar compressive strength and preferable stiffness when compared to

the other selected materials. Furthermore, bamboo’s anisotropic nature stems from the high density of

fibrous cells along the longitudinal, radial cellulose tubes, which grant bamboo flexural rigidity,

longitudinal stiffness and strength, and biodegradable properties.

Bamboo is anisotropic in nature. The large differences in direction properties (transverse and

longitudinal) is due to the large density of cellulose micro fibrils (fine fibers) in the longitudinal direction.

These micro fibrils exhibit large stiffness and strength values which transfers to the bamboo itself (CES);

however, since a lackluster amount of fibers run in the transverse direction, the strength and stiffness

values considerably smaller. For the project purposes, transverse properties should not be of primary

importance for the performance of the board, as the board is rarely introduced to shear stresses; thus,

the longitudinal properties of bamboo supplement the project well.

4.3.2Format of DOE

To conduct testing on the selected materials, a general full factorial design of experiment (DOE)

will be performed on the hypotheses created for both the core and fiber materials. This may potentially

decrease the number of tests required from a statistical perspective. Some interactions and main

effects between the core and fiber materials may not be statistically significant, which will reduce the

total number of runs per test; thus, the 27 total runs per test, computed by the multiplication of 3 fibers,

3 cores, and 3 samples per combination may contain combinations that will not impact the outcome of

the objective.

4.4 Ultrasonic Testing on Epoxy Resin

The selected epoxies are another prime component for success of the design of experiment. To

simplify the number of runs required for testing, and to facilitate the project as a whole, only one type

of epoxy was selected for every combination of fibers and cores to be generated. As such, it is crucial

that the team has access to the specific material properties of the epoxy resin, instead of generalized

values from various databases. However, after numerous attempts to contact the parent company of

the chosen epoxy, Entropy Resins Inc., the team was still unable to determine two critical values of the

epoxy/hardener combination, to be used in the composite model: shear modulus, G, and Poisson’s ratio,

ν. As such, the decision was made to complete ultrasonic testing for the given epoxy to measure the

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shear modulus, Poisson’s ratio, and elastic modulus of the material.

Ultrasonic testing utilizes a piezoelectric transducer that sends pulsating waves through the

thickness of the sample. After bouncing back from traveling the coupon’s thickness, the wave intensity

is recorded again and transmitted to the corresponding program, where the pulsating waves are plotted

on a voltage vs. time graph. Utilizing the program, the distance, or time, is measured between the two

nearest regions consisting of high amplitude peaks. These measurements ultimately determine the time

required to travel two thicknesses of each specimen, which can be incorporated with the following

equations to compute the desired properties:

eq. (1) G=V T2 ρ

eq. (2) ν=

1−2(V TV L)2

1−2(V TV L)2

eq. (3) G=V T2 ρ

(1+ν )(1−2ν )(1−ν )

Where V_T and V_L are the transverse and longitudinal velocities, respectively; ρ is the density of

the synthesized coupon; ν is Poisson’s ratio; and G and E are the shear and elastic moduli, respectively.

Coupons were formed based upon the generated standard operating procedure, provided in Appendix

G, as well as the measurement method. To ensure validity of the results, each member performed three

measurements for every specimen, and statistical analysis was conducted. Gage R & R’s (Repeatability

& Reproducibility) were completed for both the ultrasonic testing results and height measurements, and

are displayed in Appendix F. All data, including averages and finalized values, are depicted in Appendix

E. The final, calculated values from the ultrasonic testing results include the shear modulus at 600 MPa,

elastic modulus congruent to 6600 MPa, and Poisson’s ratio equal to.379. [8]

4.5 Final Concept

4.5.1Composite Model

To better determine the mechanical behavior of the composites prior to physical testing, a

mathematical model of a laminate composite was utilized. Although these calculations could be done

by hand, the time and effort it would take to calculate all combinations of materials completely and

accurately would prove to waste valuable time. For this reason, a Matlab code was written by the team

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to be used in conjunction with a computer program written by Dr. Mark. E. Tuttle of the University of

Washington called CLT to determine the behaviors of each composite. A copy of the Matlab script file

can be found in Appendix C. Additionally, both the code script file and program from Dr. Tuttle can be

found in the enterprise share drive under the team project folder if future members wish to utilize these

resources.

The Matlab code is written so that when the script is run, it will ask the user to input several

material properties for calculations. The required user inputs are as follows:

Fiber Density

Fiber Longitudinal Elastic Modulus

Fiber Transverse Elastic Modulus

Fiber Poisson’s ratio

Fiber Shear Modulus

Matrix Density

Matrix Elastic Modulus

Matrix Poisson’s ratio

Matrix Shear Modulus

When the script asks for these values, it assumes that the matrix material is isotropic.

The code, upon receiving all user inputs, will then calculate the properties of a unidirectional

laminate made with these two materials. The results are based on the fiber volume fraction, from 1 to

100 percent fiber. Upon completion of the calculations, the script then creates a figure graphing the

lamina’s longitudinal elastic modulus, transverse elastic modulus, density, Poisson’s ratio, and shear

modulus versus the volume percent of fiber. An example of the figure created by the script can be seen

in Figure C. Also, the script creates an excel file which store all of the tabulated results for further usage.

The results from the Matlab script were then inputted into the CLT program which returns tabulated

data about the composite for a given loading scenario in a text file. The two programs will be used in

conjunction to determine if any of the combinations of fibers and cores are theoretically predicted to fail

with the given loading scenario of a bend stress. An example output of the CLT program can also be

found in Appendix C. [9]

4.5.2FEA Modeling

The second theoretical model will be a FEA model of the samples which will be run in Autodesk

Inventor. The models of the samples will be based on a sandwich construction composite. The samples

will each be modeled as three separate parts combined into one assembly. There will be two lamina

layers on the top and bottom of the core that will consist of the fiber and epoxy (which will act as the

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matrix). The properties of the lamina layers will be obtained from a Lamina Matlab code written by

Stephanie. This Matlab code gives us the properties of the lamina based on the volume fraction of the

fiber to the matrix. The properties obtained from the lamina code will be input into Inventor FEA. Each

of the different combinations of core and fiber will be assessed with FEA software. The value obtained

for ultimate strength and fatigue life from the Inventor FEA simulations will be compared to the values

measured in the two ASTM standards. This will validate our results and allow use to compare our

theoretical and measured values in a precise way. The measured value for ultimate strength will also be

compared to the theoretical values obtained from the CLT software. Through the use of both of these

theoretical models we will be able to gauge how well the samples were produced and tested by

comparing the measured values to the theoretical models.

4.5.3Primary Components and Rough Budget

The budget for the project is provided below in Table 3. This version incorporates the prices for

synthesizing coupons for testing, as well as the general testing machine and hardware set prices. As the

team plans on manufacturing the product, the most expensive selected testing materials were selected

as the primary materials the boards are produced with. This allows for a possible overcompensation, in

which remaining funds will be distributed to the enterprise if the discussed materials do not succeed the

material selection process.

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Table 3: Summary of Budget

Price Unit Quantity Total Price Additional CommentsCore

PVC Cross-Linked Foam (Divinylcell) 24.00$ 8 sq. ft. 1 24.00$

0.25" thick

Extruded-Polystyrene Foam 15.00$ 4 X 8 ft. 1 15.00$ 0.5" thickBamboo Plywood 135.00$ 4 X 8 ft. 1 135.00$ 0.25" thick

FiberS-2 Grade Fiberglass 12.24$ Yard 1 12.24$ 50" wideHigh Strength Carbon Fiber 25.80$ Yard 1 25.80$ 50" wideAramid Fiber (Kevlar 29) 53.00$ Yard 4 212.00$

ResinsEntropy Super Sap SPM Epoxy/Hardener 160.00$ 3 gallon 1 160.00$

HardwareBearings 25.00$ Set 1 25.00$ Wheels 40.00$ Set 1 40.00$ Nuts/Bolts 10.00$ Set 1 10.00$ Standard Trucks 60.00$ Set 1 60.00$

Testing3-/4-Point Bending 20.00$ Hour 3 60.00$ Fatigue 20.00$ Hour 3 60.00$

TOTAL 839.04$

Materials

Fiber Reinforced Composite Longboard Deck 2014-2015 Budget

5 Term-I Work-Plan Status

5.1 Task Descriptions

At this point of 1st semester all of our possible objectives have been completed.

5.2 Timeline

A Gantt chart for our first semester can be found in Appendix D of the report. Currently we are a

little behind schedule. However, we are still on track to have everything ready to create our samples at

the start of next semester. Testing of the samples will then commence. We are still on track to finish the

project by the end of next semester.

12


Select this section (6), less the main heading. Select the same (section 5, less the main heading) in the Concept Selection Review [doc], copy and paste here. Refine as needed.You may now delete this comment (right-click on comment and choose Delete Comment).



December 12th 2014

6 Term-II Work-plan

6.1 Task Descriptions

1. Test Sample Prep

After the material has been assembled to make the samples, we need to create 27 sample coupons

for each planned ASTM test. The reason there will be 27 coupons per test is because 3 cores

combined with 3 fibers and also be 3 samples created for each combination.

2. Sample Testing

The created sample coupons will then be tested in accordance to the two selected ASTM standards

in the material testing lab of the M&M. The data gathered will determine the relative success of the

coupons. The measured values will be compared to the two theoretical models mentioned in

previous sections. The samples will first be tested with the four point bend test. The samples that

obviously fail this test will not be tested in the fatigue testing to save time. After the testing is

finished, the desired combination of fiber and core will be selected and the final deck can start to be

created.

3. Generate CAD model of board

A CAD model of the longboard deck will be created in Autodesk Inventor. This design will

incorporate popular features from other competitor’s boards while remaining unique and focusing

on performance and durability.

4. Perform FEA on Board and Optimize

After the CAD model has been created the board will be put through FEA trials in Autodesk Inventor

to identify weak points and areas where the board is overdesigned. The longboard deck will go

through several design iterations until the FEA analysis shows that the board is properly

constructed.

5. Manufacture Longboard

Once the final model of the longboard deck is created, the process of manufacturing the longboard

will begin. The selected core will be cut to the required geometry. Next, the reinforcement fiber will

be applied with epoxy. This will be achieved either a vacuum bagging method or with the BST

universal press. The board will be finished and have grip tape applied to it. Finally, a set of trucks

and wheels will be attached, making the board fully operational.

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December 12th 2014

6. Complete Real World Testing-

The constructed longboard will be tested to determine how well it has met the performance

requirements specified in our house of quality. This will consist of a number of functional

measurements like length, density, weight, stiffness, etc. The board will also be test run to

determine its functional performance on a variety of terrain.

7. Final Report

The completed board and all of the relevant information will be complied and used to write a final

report summarizing our project.

8. Final Presentation

The final report will be used to create a final presentation that will be presented to other senior

design teams and faculty.

6.2 Timeline

A Gantt chart for the second semester of our project can be found in Appendix D. The tasks for next

semester are summarized in the section above.

14



December 12th 2014

References

[1] Longboarding Information [webpage]. Available: https://www2.bc.edu/~leblanml/

[2] Fibermax Composites, Aramid Fiber Characteristics [webpage]. Available: http://www.aramid.eu/characteristics.html

[3] Glass Fibers, ASM International, Materials Park, Ohio, 2001. Pp. 1-10 Available: http://www.asminternational.org/documents/10192/1850344/06781G_p27-34.pdf/75f4a7ba-3472-4986-b59a-9ac982569763

[4] What is Carbon Fiber? [webpage]. Available: http://dragonplate.com/sections/technology.asp

[5] Divinycell Foam PVC [webpage]. Available: http://www.aircraftspruce.com/catalog/cmpages/divinycellfoam.php

[6] What is Extruded Polystyrene Insulation (XEPS)? [webpage]. Available: http://www.diversifoam.com/xeps.htm

[7] Finn McCuhil. How is Bamboo Plywood Made? [webpage]. Available: http://www.ehow.com/info_7915594_mechanical-properties-bamboo-plywood.html

[8] Epoxy Resins [webpage]. Available: http://www.pslc.ws/macrog/epoxy.htm

[9] Ed. Jose Luiz de Franca Freire, “Experimental Characterization of Composite Materials”, Experimental Mechanics, Encyclopedia of Life Support Systems (EOLSS), 2010

15


As a reminder, do not delete the hidden text code to the right (if it is showing, you will see { TC “References” \f C \I “1” }). It is used for generating its table of contents entry. You may now delete this comment (right-click on comment and choose Delete Comment).

http://www.pslc.ws/macrog/epoxy.htm

http://www.ehow.com/info_7915594_mechanical-properties-bamboo-plywood.html

http://www.diversifoam.com/xeps.htm

http://www.aircraftspruce.com/catalog/cmpages/divinycellfoam.php

http://dragonplate.com/sections/technology.asp

http://www.asminternational.org/documents/10192/1850344/06781G_p27-34.pdf/75f4a7ba-3472-4986-b59a-9ac982569763

http://www.asminternational.org/documents/10192/1850344/06781G_p27-34.pdf/75f4a7ba-3472-4986-b59a-9ac982569763

http://www.aramid.eu/characteristics.html

https://www2.bc.edu/~leblanml/



December 12th 2014

Appendix A — House of Quality – Customer Focus

16



December 12th 2014

House of Quality – Stakeholders versus Stakeholder needs

17



December 12th 2014

House of Quality – Stakeholder needs versus Engineering Requirements

18



December 12th 2014

House of Quality – Engineering Requirements versus Functions

19



December 12th 2014

Appendix B — Selection and Design (CES GRAPHS)

20



December 12th 2014

Appendix C — Composite Model Examples

This is a copy of the Matlab script file used for the composite calculations.

clc,clear%this prgram will calculate some cool stuff relating to composites rho_matrix=input('What is the density of the polymer matrix?: ');rho_fiber=input('What is the density of the fiber?: ');E_fiber_long=input('What is the longitudinal modulus of the fiber?: ');E_fiber_trans=input('What is the transverse modulus of the fiber?: ');E_matrix=input('What is the modulus of the matrix?: ');V_fiber=input('Poissons ratio for the fiber?: ');V_matrix=input('Poissons ratio for the matrix?: ');E_mprime=E_matrix/(1-V_matrix^2);G_fiber=input('What is the shear modulus of the fiber?: ');G_matrix=input('What is the shear modulus of the matrix?: '); for i=1:1:100 percent_fiber(i)=i; volume_fraction_f(i)=i/100; volume_fraction_m(i)=1-volume_fraction_f(i); rho_lamina(i)=rho_fiber*volume_fraction_f(i)+rho_matrix*volume_fraction_m(i); V_lamina(i)=V_fiber*volume_fraction_f(i)+V_matrix*volume_fraction_m(i); G_lamina(i)=(volume_fraction_f(i)/G_fiber+volume_fraction_m(i)/G_matrix)^-1; E_1lamina(i)=E_fiber_long*volume_fraction_f(i)+E_matrix*volume_fraction_m(i); E_2lamina(i)=(volume_fraction_f(i)/E_fiber_trans+volume_fraction_m(i)/E_mprime)^-1; end figure(1)subplot(2,3,1)plot(percent_fiber,rho_lamina)xlabel('percent fiber')ylabel('density, kg/m^3')title('Composite Density based on percent fiber') subplot(2,3,2)plot(percent_fiber,E_1lamina)xlabel('percent fiber')ylabel('Youngs Modulus, Pa')title('Youngs modulus as a function of percent fiber') subplot(2,3,3)plot(percent_fiber,E_2lamina)

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December 12th 2014

xlabel('percent fiber')ylabel('Youngs Modulus, Pa')title('Youngs modulus as a function of percent fiber') subplot(2,3,4)plot(percent_fiber,V_lamina)xlabel('percent fiber')ylabel('Poissons ratio')title('Poissons ratio as a function of percent fiber') subplot(2,3,5)plot(percent_fiber,G_lamina)xlabel('percent fiber')ylabel('Shear Modulus, Pa')title('Shear Modulus as a function of percent fiber') A=rot90(rot90(rot90(percent_fiber)));B=rot90(rot90(rot90(rho_lamina)));C=rot90(rot90(rot90(E_1lamina)));D=rot90(rot90(rot90(E_2lamina)));E=rot90(rot90(rot90(V_lamina)));F=rot90(rot90(rot90(G_lamina))); filename='Lamina Calculations Results.xlsx';xlswrite(filename,A,1,'A1')xlswrite(filename,B,1,'B1')xlswrite(filename,C,1,'C1')xlswrite(filename,D,1,'D1')xlswrite(filename,E,1,'E1')xlswrite(filename,F,1,'F1')

This is an example of the output text file for the CLT program created by Dr. Mark Tuttle at the

University of Washington.

22



December 12th 2014

***PROGRAM CLT*****

WRITTEN BY PROF. MARK E. TUTTLE

DEPARTMENT OF MECHANICAL ENGINEERING

UNIVERSITY OF WASHINGTON

THIS PROGRAM PERFORMS AN ANALYSIS OF A MULTI-PLY,

MULTI-ANGLE COMPOSITE LAMINATE, IN ACCORDANCE WITH

CLASSICAL LAMINATION THEORY

THE 2 MATERIALS PROPERTIES INPUT:

MATL E11 E22 NU12 G12

1 0.346E+05 0.360E+04 0.37 0.777E+03

2 0.175E+05 0.175E+04 0.39 0.128E+04

MATL ALP11 ALP22 BETA11 BETA22 THICKNESS

1 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.645000

2 0.000E+00 0.000E+00 0.000E+00 0.000E+00 6.350000

LAMINATE DESCRIPTION:

LAMINATE IS SYMMETRIC

TOTAL NUMBER OF PLIES = 6

TOTAL LAMINATE THICKNESS = 15.280001

PLY MATL FIBER

NO. NO. THICKNESS ANGLE

1 1 0.645000 45.00

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December 12th 2014

2 1 0.645000 -45.00

3 2 6.350000 0.00

4 2 6.350000 0.00

5 1 0.645000 -45.00

6 1 0.645000 45.00

LAMINATE LOADING:

LAMINATE SUBJECTED TO KNOWN STRESS AND MOMENT RESULTANTS:

Nxx Nyy Nxy Mxx Myy Mxy

0.0 0.0 0.0 ********* 0.00 0.00

STRESS-FREE TEMPERATURE = 0.0

SERVICE TEMPERATURE = 0.0

CHANGE IN TEMPERATURE = 0.0

CHANGE IN MOISTURE CONTENT = 0.0

STIFFNESS MATRICES:

THE [Q] MATRIX FOR MATERIAL NUMBER 1:

0.350970E+05 0.135262E+04 0.000000E+00

0.135262E+04 0.365573E+04 0.000000E+00

0.000000E+00 0.000000E+00 0.777000E+03

THE [Q] MATRIX FOR MATERIAL NUMBER 2:

24



December 12th 2014

0.177703E+05 0.693041E+03 0.000000E+00

0.693041E+03 0.177703E+04 0.000000E+00

0.000000E+00 0.000000E+00 0.128500E+04

THE [QBAR] MATRIX FOR PLY NUMBER 1:

0.111415E+05 0.958748E+04 0.786031E+04

0.958748E+04 0.111415E+05 0.786031E+04

0.786031E+04 0.786031E+04 0.901186E+04


0.111415E+05 0.958748E+04 -0.786031E+04

0.958748E+04 0.111415E+05 -0.786031E+04

-0.786031E+04 -0.786031E+04 0.901186E+04


0.177703E+05 0.693041E+03 0.000000E+00

0.693041E+03 0.177703E+04 0.000000E+00

0.000000E+00 0.000000E+00 0.128500E+04


0.177703E+05 0.693041E+03 0.000000E+00

0.693041E+03 0.177703E+04 0.000000E+00

0.000000E+00 0.000000E+00 0.128500E+04


0.111415E+05 0.958748E+04 -0.786031E+04

0.958748E+04 0.111415E+05 -0.786031E+04

25



December 12th 2014

-0.786031E+04 -0.786031E+04 0.901186E+04


0.111415E+05 0.958748E+04 0.786031E+04

0.958748E+04 0.111415E+05 0.786031E+04

0.786031E+04 0.786031E+04 0.901186E+04

THE [ABD] MATRIX IS:

0.25443E+06 0.33537E+05 0.28221E-03 -0.12258E+00 -0.23097E-01 0.33372E-04

0.33537E+05 0.51313E+05 0.28221E-03 -0.23097E-01 -0.28828E-01 0.33372E-04

0.28221E-03 0.28221E-03 0.39570E+05 0.33372E-04 0.33372E-04 -0.18834E-01

-0.12258E+00 -0.23097E-01 0.33372E-04 0.44438E+07 0.13320E+07 0.91497E+05

-0.23097E-01 -0.28828E-01 0.33372E-04 0.13320E+07 0.17138E+07 0.91497E+05

0.33372E-04 0.33372E-04 -0.18834E-01 0.91497E+05 0.91497E+05 0.13602E+07

THE [abd] MATRIX IS:

0.43009E-05 -0.28110E-05 -0.10626E-13 0.13147E-12 -0.91357E-13 -0.27346E-14

-0.28110E-05 0.21325E-04 -0.13204E-12 -0.81842E-13 0.38556E-12 -0.20884E-13

-0.10626E-13 -0.13204E-12 0.25272E-04 -0.21554E-14 -0.17569E-13 0.35124E-12

0.13147E-12 -0.81842E-13 -0.21554E-14 0.29341E-06 -0.22781E-06 -0.44123E-08

-0.91357E-13 0.38556E-12 -0.17569E-13 -0.22781E-06 0.76248E-06 -0.35965E-07

-0.27346E-14 -0.20884E-13 0.35124E-12 -0.44123E-08 -0.35965E-07 0.73789E-06

THERMAL STRESS AND MOMENT RESULTANTS ARE:


0.0 0.0 0.0 0.00 0.00 0.00

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December 12th 2014

MOISTURE STRESS AND MOMENT RESULTANTS ARE:


0.0 0.0 0.0 0.00 0.00 0.00

CALCULATED MIDPLANE STRAINS AND CURVATURES ARE:

EPSxx EPSyy GAMxy kxx kyy kxy

0.000000 0.000000 0.000000 0.795638 -0.617764 -0.011965

EFFECTIVE LAMINATE PROPERTIES:

"EXTENSIONAL" IN-PLANE PROPERTIES

Exx Eyy NUxy NUyx Gxy

0.152E+05 0.307E+04 0.654 0.132 0.259E+04

ETAxy,xx ETAxy,yy ETAxx,xy ETAyy,xy

0.000 0.000 0.000 0.000

IN-PLANE THERMAL AND MOISTURE EXPANSION COEFFICIENTS

ALPxx ALPyy ALPxy

0.000E+00 0.000E+00 0.000E+00

BETAxx BETAyy BETAxy

0.000E+00 0.000E+00 0.000E+00

"FLEXURAL" PROPERTIES

Exxf Eyyf NUxyf NUyxf

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December 12th 2014

0.115E+05 0.441E+04 0.776 0.299

LAMINATE PLY STRAINS, x-y COORDINATE SYSTEM:

PLY NO Z-COORD EPSxx EPSyy GAMxy

------- -0.764E+01 -6.078676 4.719720 0.091412

1

------- -0.700E+01 -5.565490 4.321262 0.083694

2

------- -0.635E+01 -5.052303 3.922804 0.075977

3

------- -0.477E-06 0.000000 0.000000 0.000000

4

------- 0.635E+01 5.052303 -3.922804 -0.075977

5

------- 0.699E+01 5.565490 -4.321262 -0.083694

6

------- 0.764E+01 6.078676 -4.719720 -0.091412

LAMINATE PLY STRAINS, 1-2 COORDINATE SYSTEM:

PLY NO Z-COORD EPS11 EPS22 GAM12

-------------------------------------------------------------

-0.76400E+01 -0.633772 -0.725184 10.798396

1

-0.69950E+01 -0.580267 -0.663961 9.886751

-------------------------------------------------------------

-0.69950E+01 -0.663961 -0.580267 -9.886751

2

-0.63500E+01 -0.602738 -0.526761 -8.975106

-------------------------------------------------------------

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December 12th 2014

-0.63500E+01 -5.052303 3.922804 0.075977

3

-0.47684E-06 0.000000 0.000000 0.000000

-------------------------------------------------------------

-0.47684E-06 0.000000 0.000000 0.000000

4

0.63500E+01 5.052303 -3.922804 -0.075977

-------------------------------------------------------------

0.63500E+01 0.602738 0.526761 8.975106

5

0.69950E+01 0.663961 0.580267 9.886751

-------------------------------------------------------------

0.69950E+01 0.580267 0.663961 -9.886751

6

0.76400E+01 0.633772 0.725184 *********

--------------------------------------------------------------

LAMINATE PLY STRESSES, x-y COORDINATE SYSTEM:

PLY NO Z-COORD SIGxx SIGyy TAUxy

--------------------------------------------------------------

-0.76400E+01 -0.21757E+05 -0.49760E+04 -0.98580E+04

1

-0.69950E+01 -0.19920E+05 -0.45559E+04 -0.90258E+04

--------------------------------------------------------------

-0.69950E+01 -0.21236E+05 -0.58716E+04 0.10534E+05

2

-0.63500E+01 -0.19278E+05 -0.53302E+04 0.95629E+04

--------------------------------------------------------------

-0.63500E+01 -0.87062E+05 0.34695E+04 0.97630E+02

3

-0.47684E-06 -0.35644E-03 0.11322E-03 -0.17919E-06

29



December 12th 2014

--------------------------------------------------------------

-0.47684E-06 -0.35644E-03 0.11322E-03 -0.17919E-06

4

0.63500E+01 0.87062E+05 -0.34695E+04 -0.97630E+02

--------------------------------------------------------------

0.63500E+01 0.19278E+05 0.53302E+04 -0.95629E+04

5

0.69950E+01 0.21236E+05 0.58716E+04 -0.10534E+05

--------------------------------------------------------------

0.69950E+01 0.19920E+05 0.45559E+04 0.90258E+04

6

0.76400E+01 0.21757E+05 0.49760E+04 0.98580E+04

--------------------------------------------------------------

LAMINATE PLY STRESSES, 1-2 COORDINATE SYSTEM:

PLY NO Z-COORD SIG11 SIG22 TAU12

--------------------------------------------------------------

-0.76400E+01 -0.23224E+05 -0.35083E+04 0.83904E+04

1

-0.69950E+01 -0.21264E+05 -0.32121E+04 0.76820E+04

--------------------------------------------------------------

-0.69950E+01 -0.24088E+05 -0.30194E+04 -0.76820E+04

2

-0.63500E+01 -0.21867E+05 -0.27410E+04 -0.69737E+04

--------------------------------------------------------------

-0.63500E+01 -0.87062E+05 0.34695E+04 0.97630E+02

3

-0.47684E-06 -0.35644E-03 0.11322E-03 -0.17919E-06

--------------------------------------------------------------

-0.47684E-06 -0.35644E-03 0.11322E-03 -0.17919E-06

4

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December 12th 2014

0.63500E+01 0.87062E+05 -0.34695E+04 -0.97630E+02

--------------------------------------------------------------

0.63500E+01 0.21867E+05 0.27410E+04 0.69737E+04

5

0.69950E+01 0.24088E+05 0.30194E+04 0.76820E+04

--------------------------------------------------------------

0.69950E+01 0.21264E+05 0.32121E+04 -0.76820E+04

6

0.76400E+01 0.23224E+05 0.35083E+04 -0.83904E+04

--------------------------------------------------------------

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December 12th 2014

Appendix D — Gantt Chart

1st Semester

2nd Semester

32



December 12th 2014

Appendix E- Collected Data from Ultrasonic Testing

33

Table 3: Ultrasonic Measurements of Hardened Epoxy SpecimensSample 1 Sample 2 Sample 3 Sample 4 Sample 5

14.78 14.46 14.61 14.70 14.67 14.43 14.18 14.52 14.43 15.17 14.87 14.74 14.47 14.67 14.64

14.72 14.61 14.72 14.67 14.46 14.58 14.39 14.40 14.34 14.99 14.75 14.81 14.54 14.55 14.64

14.70 14.67 14.58 14.58 14.70 14.52 14.25 14.67 14.37 15.02 14.87 14.72 14.54 14.70 14.73

Average 14.73 14.58 14.64 14.65 14.61 14.51 14.27 14.53 14.38 15.06 14.83 14.76 14.52 14.64 14.67

Measured Time, t

(μs)

Table 2: Height Measurements of Hardened Epoxy SpecimensSample 1 Sample 2 Sample 3 Sample 4 Sample 5

Step

hani

e

Austi

n

Stev

e

Step

hani

e

Austi

n

Stev

e

Step

hani

e

Austi

n

Stev

e

Step

hani

e

Austi

n

Stev

e

Step

hani

e

Austi

n

Stev

e

0.322 0.323 0.324 0.321 0.3205 0.321 0.32 0.321 0.3205 0.327 0.329 0.328 0.324 0.321 0.323

0.323 0.323 0.3245 0.321 0.321 0.322 0.32 0.3195 0.321 0.328 0.3285 0.330 0.322 0.323 0.3225

0.322 0.3225 0.323 0.321 0.321 0.321 0.32 0.3205 0.321 0.325 0.325 0.328 0.323 0.322 0.3235

Average 0.322 0.323 0.324 0.321 0.321 0.321 0.320 0.320 0.321 0.327 0.328 0.329 0.323 0.322 0.323

Measured length,

l (in)



December 12th 2014

Appendix F- Gauge R&R from ultrasonic Testing

Gauge R&R for time measurements

Gauge R&R for height measurements

Appendix G – Standard Operating Procedure

34



December 12th 2014

Appendix G- Standard Operating procedure for Ultrasonic testing

Epoxy Resin Sample Preparation1. Gather the amount of mounting cups necessary to complete the desired amount of

samples. These cups should be about ½ in. in diameter, but no smaller.2. Clean each mounting cup if necessary, and spray a liberal amount of silicone release on the

inside of each cup.3. If desired, mark the height on the inside of the mounting cup at which the thickness of each

sample should be. Standard sample heights average to about ½ in.4. Stir the epoxy and hardener in the proper proportions as indicated by the manufacturer,

until the resin is uniform and consistent.5. Pour the epoxy into each cup until the epoxy height is slightly above the desired sample

height, which allows for polishing. Stir the poured epoxy to remove the evolved hydrogen gas, but do not introduce new air bubbles into the sample.

6. Allow the samples to harden and cure. Usually 24 hours is sufficient.7. Afterwards, carefully remove the samples from the mounting cups, inspect the general

quality of each, and eliminate specimens with a large amount of air bubbles.8. Polish each sample on the faces, until the two faces are parallel. This reduces the

attenuation of the wave, and allows the strongest readout as possible.9. Once polishing is completed, place the specimens in a sample bag with proper labeling.

Ultrasonic Testing Procedure1. Turn the power on and startup the corresponding computer. Log in and open the DSO-

2250USB program located on the desktop, or the software equivalent.2. Determine if the testing requires the longitudinal transducer, the transverse transducer, or

both, and plug in the desired cords into the control panel.3. Set the software parameters for the desired testing. For this particular epoxy:

a. Checked CH2 boxb. Format: Y-Tc. DCd. X1e. Trigger Mode: edgef. Trigger Sweep: autog. Trigger Source: CH2

4. Apply a miniscule amount of ultrasonic couplant D for the longitudinal transducer or dark brown substrate for the transverse transducer to the surface of the piezoelectric transducer currently in use. After spreading the goop, a thin film should be present on the face.

5. Place the head of the transducer on the top of the sample, without holding onto the cable joint. Firmly and steadily move the piezoelectric head around on the specimen until the graph area of the program displays a large signal. Two periods of large amplitudes of waves should appear.

6. Once an adequate graph has been produced, by moving the transducer head on the sample and tuning the time/DIV and graph range, click the stop button on the top toolbar.

35



December 12th 2014

7. Usually only the time it takes the wave to travel two thicknesses of the coupons is required to determine the shear modulus, and consequently poisson’s ratio, of the material. Place the cursor at the peak of the first amplitude of the first period. Click and drag the cursor to the first peak of the second period. For polymers and epoxies, these two amplitudes should be reciprocals of one another.

8. Read and tabulate the time value in the bottom left hand corner of the screen.9. Click the play button to resume live capture measurements.10. Repeat steps 4 - 9 for each sample, while cleaning the water-soluble goop off the surface of

each specimen between measurements11. When finished, clean all samples off with water, unplug the transducers, and power down

the equipment. Log off the computer and properly take care of the equipment.

36

Documents

Semester 1 Composite Longboard Critical Design Review