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PARAMETRIC SOLID MODELING PROGRAM

YEAR 3: LECTURE NOTES

DEPARTMENT OF ENGINEERING AND INFORMATICS

NUI GALWAY

BIOMEDICAL ENGINEERING

2020-2021

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LECTURER: WARREN DAVIES

DESIGN OFFICE LECTURER

Polak-Krasna, Katarzyna (Kate)

HEAD OF DEPARTMENT:

PROFESSOR PETER McHUGH

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Table of Contents

CONTENTS PAGE

NUMBER

Title Page. 1

Contents. 2

Course Curriculum / Assessment Criteria 3

1.3 Complex Lofting 4

1.4 3D Sketching 12

1.5 Hip implants 20

1.6 Stents 24

1.7 Delivery Systems 28

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1.1: COURSE CURRICULUM

1.2: ASSESSMENT CRITERIA

Advanced Parts & Drawings

Advanced Assembly & Drawings

Hip Modeling

Stent Modeling

Stent Delivery Systems

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1.3: Complex Lofting

Choose sections to act as loft profiles.

Output as a solid or surface.

Merge tangent faces to remove joining lines.

Join the first and last sections to form a closed loop.

Rails are 2D curves, 3D curves, or model edges that determine the loft shape between a number

sections.

Rails must intersect profile sections and must not extend beyond sections

.

Centerline rails keep the loft section normal to the rail. They do not need to intersect the

profiles. Only one centreline can be used as a rail.

Area Loft controls cross sectional areas at points along a centreline.

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LOFT TOOL – Conditions.

The Conditions tab defines boundary conditions for end sections, and for outermost rails. Apply conditions to rails of an

open section loft that borders adjacent surfaces, or a loft with sections that begin or end at a point. The boundary

conditions control the shape of the loft body near its boundary.

Using Conditions Click the condition icon, and then select the boundary condition from the list.

Free condition No boundary conditions.

Tangent (G1) condition Available when the section or rail is next to a lateral surface or body, or

when the selection is a face loop. (To project a face boundary automatically, in the Application Options dialog

box, Sketch tab, select Automatic reference edges for new sketch. )

Smooth (G2) condition Available when the section or rail is next to a lateral surface or body, or when

the selection is a face loop. Enables curvature continuity for beginning and end loft sections and rails.

Direction condition Available only when the curve is a 2D sketch. Measures the angle relative to the

section plane.

Sharp point Available only when the beginning or end section is a point. Applies no boundary condition.

Enables a direct transition from an open or closed section to a pointed or cone-shaped tip.

Tangent Available only when the beginning or end section is a point. Applies tangency. Enables the loft

section to transition to a rounded, or dome-shaped point.

Tangent to plane Available only when the beginning or end section is a point. Applies tangency to the point

based on a selected plane. Enables the loft section to transition to a rounded dome shape. Select a planar

face, or work plane. Not available for use with the center line.

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Angle Represents the transition angle between the section or rail

plane, and the faces created by the loft. The default value of 90 degrees provides a perpendicular transition. A

180 degree value provides a planar transition. The range is from 0 to 180 degrees.

Weight: A unitless factor that controls the appearance of the loft. Determines how far the section shape

extends before it transitions into the next shape. Large weight values can result in twisting of the lofted surface

and cause a self intersecting surface. Typical weight factors range from 1 to 20. Large and small values are

relative to the size of your model.

Creating Splines

Sketch interpolation splines:

You can create 2d interpolation splines in the 2d sketch environment by positioning points and then drawing the

spline between the points or by entering coordinates in the precise input tool. Interpolation splines are drawn

directly through the points chosen. You normally use absolute Cartesian coordinate points which is the default

setting in the precise input tool and only enter X and Y values. (Use the tab key to switch between input boxes)

You can create 3d interpolation splines in the 3d sketch environment in much the same way with the difference that

you also include a Z coordinate.

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Edit Interpolation Splines Drag a point to reposition it.

Drag an end point to resize the shape.

Drag the spline to move or reposition it.

Create a sketch point at a particular

coordinate and coincident constrain a point on the spline to it.

To edit the shape of the curve, right-click a tangent handle and choose Activate Handle. Then, drag the tangent

handle to adjust the spline shape.

To delete a spline, select it and press Delete.

To add a point, right-click the spline and choose Insert Point. Then click the curve to add one or more points.

Press Esc when you’re done.

To close a curve, right-click the starting point and choose Close Curve.

To delete a point, select it and press Delete.

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Tip: To delete the spline but preserve the fit points, convert the points to center points, then select the spline

and press Delete.

To split a spline, right-click a point and choose Split Spline.

To reverse an edit, right-click the spline and choose Reset Handle or Reset All Handles.

To change the fit method, right-click a spline choose one of the following:

Standard. Creates curves with smooth continuity between points.

Minimum Energy. Creates smooth curves with high visual appeal and better curvature

distribution. Because Minimum Energy splines contain more data, surfaces generated using

them take longer to calculate and create larger files.

AutoCAD. Uses the AutoCAD spline-fitting method. Interpolation splines that use the

AutoCAD fit method do not have handles and are not suitable for creating class A surfaces.

Creating Sketch Points

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You can create center or sketch points, change point style, move or delete points, import points from Microsoft

Excel, and import points from a STEP or IGES File.

Sketch points, which represent points in space, can be either points or center points. Inventor places center points

by default, but you can change the type using the Format panel.

A sketch point creates a construction point to help position sketch geometry. For example, the Hole command uses

center points to automatically position hole features. In the graphics window, regular

sketch points appear as dots. Center points appear as cross-hair symbols.

You place points on a sketch plane in 2D sketches or in 3D space according to the current plane view. Or, you can select

vertices of existing geometry to place points. Sketch points are created without constraints. You can dimension or

constrain the points to other geometry in the sketch, or constrain points to other sketches or existing model geometry.

Create Center Points or Sketch Points

1. In an active sketch, do one of the following:

(2D sketch) Click Sketch tab > Create panel > Point .

(3D sketch) 3D Sketch tab > Draw panel Point

2. Click in the graphics window to place points or use precise input to place using absolute or relative Cartesian

coordinates.

3. To precisely position a point on 2D existing geometry, right-click and do one of the following:

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Select Point Snaps > Midpoint, and click a line or curve.

Select Point Snaps > Center, and click a circle or ellipse.

Select Point Snaps > Apparent Intersection, and click two intersecting elements.

Select Point Snaps > Intersection, and click intersecting point of two or

more elements.

Select Point Snaps > Endpoint, and click a line or curve.

Select Point Snaps > Quadrant, and click a circle or ellipse.

Select Point Snaps > Tangent, and click a curve.

Select Point Snaps > Mid of 2 points, and click two points.

• To change between center points and sketch points, click Format panel > Center Point before you create or

import points.

Move or Delete Points

To remove a point from a sketch, select it and press Delete.

To move a 3D sketch point, right-click it and choose 3D Move/Rotate. Then, choose Redefine

Alignment or Position and enter new X, Y, and Z coordinates.

Import Points from Microsoft Excel

You can import points from a Microsoft Excel spreadsheet into an 2D or 3D Inventor sketch. By default, points are

imported as sketch points. Imported points are not associated with the source file. Changes to the source file after

importing do not affect the Inventor geometry. If you’re importing points into a 2D sketch and the spreadsheet contains

Z values, only X and Y values are imported.

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Import Points from a STEP or IGES File

1. On the Quick Access toolbar, click Open.

2. In the Open dialog box, choose Files of Type > STEP Files (*.stp; *ste; .step) or Files of Type > IGES Files

(.igs; *.igs;*.ige;*.iges).

Note: You can also import points upon translation when you open a DWG file in Inventor.

3. Navigate to and select a file to open.

4. Click Options.

5. In the Import Options dialog box, in Entities to Import, ensure that Points is selected, and set the remaining

options.

6. Click OK and then click Open.

Inventor creates a 3D sketch for the imported points. The sketch is named for the layer or group that contains

the points in the STEP or IGES file or, if no layer or group information is available, the sketch takes on a

default name, such as Sketch1.

Best Practices for Importing Points

When preparing to import points from another application, consider the following:

• The table of points must be the first worksheet in the file and must start at cell A1.

• Any unit of measure that the first cell (A1) contains applies to all points in the spreadsheet. If no units are

specified, the default file units apply.

• Required column order is Column A is the X coordinate, Column B is the Y coordinate, and Column C is the Z

coordinate.

• Cells can contain a formula that calculates to a numeric value.

• Points correspond to the spreadsheet rows. The first imported point corresponds to the first row of coordinates,

and so on. If a spline or line is created automatically, it begins at the first point, and passes through the other

points, based on their order of import.

• When importing with lines into 3D sketches, Inventor automatically generates tangent corner bends if Auto-

Bend with 3D Line Creation is turned on in Tools tab Options panel Application Options Sketch tab.

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1.4: 3D Sketching Tools

Lines

The 3D Line tool draws lines in 3D space without bends between segments. To apply bends use the bend tool.

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Alternative ways of producing bends are:

Right-click and do one of the following:

Select Auto-Bend to automatically place 3D arcs at corners of 3D lines using the last set radius.

Clear the Auto-Bend option to disable automatic bends.

To draw the lines

1. In the graphics window, click to set the start point.

2. (Optional) Do any of the following:

o Continue clicking to create contiguous segments.

o Click a different plane on the coordinate triad to place the next sketch point on that plane.

o To restrict selections to a plane, right-click, select Align to Plane, then select the plane. To return to

the standard selection mode, right-click and select Align to Plane again.

o To create a break in a 3D line, click to end the current line. Right-click, select Restart, and then click a

valid point to begin another line.

3. To end, right-click and choose Done.

Create Three Point or Center Point Arcs

The Arc tools create arcs by placing three points — a center point and two endpoints.

1. In an active sketch, click Sketch tab Create panel (2D sketch) or Draw panel (3D sketch) and choose one of

the following:

o Three Point Arc . Creates an arc defined by two endpoints and a point on the arc. The first click sets

the first endpoint, the second sets the other endpoint (chord length), and the third point sets the arc

direction and radius.

o Center Point Arc . Creates an arc defined by its center point and two endpoints. The first click sets the

center point, the second specifies the radius and start point, and the third point completes the arc.

2. In the graphics window, click to place the first point of the arc.

3. Move the cursor and click to set the second point.

4. Move the cursor to preview the arc direction and click to set the last point.

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Helical Curves

The Helical Curve tool creates 3D coil shapes, such as springs and threads. Helical curves can be joined with other

sketch entities to create a complex sweep path.

Note: The 2D Coil command differs from the Helical Curve in that it requires a closed 2D sketch profile and an axis to

create a feature.

1. In an active 3D sketch, click 3D Sketch tab Draw panel Helical Curve .

2. In the Helical Shape tab of the Helical Curve dialog box, choose a Type:

o Pitch and Revolution. Creates a helical curve based on a specified pitch and number of revolutions.

o Revolution and Height. Creates a helical curve based on a specified number of revolutions and a

height.

o Pitch and Height. Creates a helical curve based on a specified pitch and height.

o Spiral. Creates a helical curve based on a specified number of revolutions.

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3. Enter values for the type of shape you specified:

Diameter (Optional). The diameter of the helical curve. Inventor calculates the diameter automatically

based on height, pitch, and revolution. The point on diameter is projected into the plane (normal to

centerline) of the start point.

Height. The height of the helical curve.

Pitch. The elevation gain for each revolution.

Revolutions. The number of revolutions must be greater than zero but can include partial revolutions,

such as 1.5. If specified, the number of revolutions includes the end conditions.

Taper. The taper angle, if needed, for all shape types except Spiral.

4. Click a Rotation option: clockwise or counterclockwise.

5. On the Helix Ends tab of the Helical Curve dialog box, specify conditions for the Start and End points of the

curve:

Natural

The distance (in degrees) over which the curve achieves the transition (normally less than one revolution). The

following example shows the top with a natural end and the bottom end

with a one-quarter turn transition (90 degrees) and no flat angle:

Flat

The distance (in degrees) that the curve extends after transition with no pitch (flat). Provides transition from the

end of the revolved helical curve to a flattened end. The example shows the same helical curve as the

Transition angle in the previous image, but with a half-turn

(180 degree) flat angle specified:

6. In the graphics window, click to define the start point of the curve and then click to define the end point.

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Complex Modeling

1 - Intersection Curves:

2 - Silhouette Curves:

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3 - Project Curves to Surface

( 1 ) ( 2 ) ( 3 )

1 Project Along Vector . (Default) Projects the geometry along a specified vector. Allows you to also

select a Direction for the vector.

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2 Project to Closest Point. Projects onto a surface normal to the closest point.

3 Wrap to Surface Wraps curves or ponts from a 2D sketch onto a face or faces. This type of projection

preserves the curve length. The sketch must be tangent or parallel to a plane that is tangent to one of the selected

faces. The wrap starts from the tangency. You can’t wrap 3D sketch curves and points, model edges, or surface

edges.

Tip: A developable face is one that can be wrapped with a plane without stretching or compressing the

plane. Planes, cones, and cylinders are all developable faces.

1. In the graphics window, click to select the face onto which you want to project.

Tip: You can also select surface features in the browser or by right-clicking and choosing Select Other.

2. In the Project Curve to Surface dialog box, click the Curves the selection tool.

Curves selections can include 2D or 3D curves, vertices or work points, sketch points, or part or surface edges.

This option can be used to create stents by wrapping paths around cylindrical features. Please note however that

approximations of facets in 3d Models in the newer versions of inventor may results in poor 3d Representation.

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4 - Curves on Face

5 - Include Geometry

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1-5: Hip Replacement Design.

Hip Implants

Hip implants are medical devices intended to restore mobility and relieve pain usually

associated with arthritis and other hip diseases or injuries. Every hip implant has a distinct

set of benefits and risks. The key design features of each implant including size, material and

dimensions make each system unique. In addition, the same hip implant system will have

different outcomes in different patients. It is also important to recognize that hip implants

may need to be replaced eventually. Factors that influence the longevity of the device

include the patient’s age, sex, weight, diagnosis, activity level, conditions of the surgery, and

the type of implant chosen.

In the United States, there are currently five types of total hip replacement devices available

with different bearing surfaces. These are:

• Metal-on-Polyethylene: The ball is made of metal and the socket is made of plastic

(polyethylene) or has a plastic lining.

• Ceramic-on-Polyethylene: The ball is made of ceramic and the socket is made of plastic

(polyethylene) or has a plastic lining.

• Metal-on-Metal: The ball and socket are both made of metal.

• Ceramic-on-Ceramic: The ball is made of ceramic and the socket has a ceramic lining.

Ceramic-on-Metal: The ball is made of ceramic and the socket has a metal lining.

An orthopaedic surgeon should determine which hip implant will offer the most benefit and least

risk for each patient. When making a recommendation, orthopaedic surgeons should consider

several factors such as the patient’s age, weight, height, activity level, and cause of hip pain. Hip

surgery may involve total hip replacement or it may involve hip resurfacing.

During total hip replacement surgery, the damaged portions of the hip joint are removed. The

ball (femoral head) is removed and replaced with a prosthetic ball made of metal or ceramic, and

the socket (acetabulum) is removed and replaced with a prosthetic cup. The cup consists of one

or two components made of metal, ceramic or plastic. A stem is also placed in the femur to

support the femoral head. The femoral head attaches to the taper of the stem.

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During hip resurfacing surgery, the femoral head is not removed. Instead the femoral head

is trimmed and capped with a metal covering. Any damaged bone and cartilage within the

socket are removed and replaced with a metal shell. In hip resurfacing surgery, both

components are made of metal.

Freeman Femoral Stems

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Townley Platform Stem. Whiteside Neck Sparing Stem.

Summit Cementless Hip System

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Multi Part Hip Device

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1-6: Stent Design.

STENTS

.

Coronary arteries

The most widely known stent use is in the coronary arteries with a bare-metal stent, a drug-eluting

stent or occasionally a covered stent.

Coronary stents are placed during a percutaneous coronary intervention procedure, also known as an

angioplasty.

Urinary Tract

Ureteral stents are used to ensure the patency of a ureter, which may be compromised, for example,

by a kidney stone. This method is sometimes used as a temporary measure, to prevent damage to a

blocked kidney, until a procedure to remove the stone can be performed. Indwelling times of 12

months or longer are indicated to hold ureters open, which are compressed by tumors in the

neighbourhood of the ureter or by tumors of the ureter itself. In many cases these tumors are

inoperable and the stents are used to ensure drainage of urine through the ureter. If drainage is

compromised for longer periods, the kidney can be damaged. The main complications with ureteral

stents are dislocation, infection and blockage by encrustation. Recently stents with coatings (e.g.

heparin) were approved to reduce infection, encrustation and therefore stent exchanges.

Urethral / Prostatic stent

A urethral or Prostatic stent might be needed if a man is unable to urinate. Often this situation

occurs when an enlarged prostate pushes against the urethra, blocking the flow of urine. The

placement of a stent can open the obstruction, avoiding the collapse of the urethra. Urethral stent are

now rarely used as a permanent treatment as they have grown to have a very bad reputation for

failing and having to be removed.

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Vascular

Stents are used in a variety of vessels aside from the coronary arteries.

Peripheral vascular

Stents may be used as a component of peripheral artery angioplasty.

Stent Graft

A stent graft is a tubular device, which is composed of special fabric supported by a rigid structure,

usually metal. The rigid structure is called a stent. An average stent on its own has no covering, and

therefore is usually just a metal mesh. Although there are many types of stent, these stents are used

mainly for vascular intervention.

The device is used primarily in endovascular surgery. Stent grafts are used to support weak points in

arteries, such a point commonly known as an aneurysm. Stent grafts are most commonly used in the

repair of an abdominal aortic aneurysm, in a procedure called an EVAR. The theory behind the

procedure is that once in place inside the aorta, the stent graft acts as a false lumen for blood to

travel through, instead of flowing into the aneurysm sack.

Other

• CHD Stent

• Oesophageal Stent

• Duodenal Stent

• Colonic Stent Biliary Stent

• Pancreatic Stent

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http://www.peripheral.medtronicendovascular.com/international/producttype/stents/completese/index.htm

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1-7: Catheter Design.

STENT DELIVERY SYSTEMS

Angioplasty and Stenting

In this technique, the interventional radiologist inserts a very small balloon attached to a thin catheter into a blood vessel through a small nick in the skin. The catheter is threaded under X-ray guidance to the site of the blocked artery. The balloon is inflated to open the artery. Sometimes, a small metal scaffold, called a stent, is inserted to keep the blood vessel open.

Balloon angioplasty and stenting have generally replaced open surgery as the firstline treatment because randomized trials have shown interventional therapy to be as effective as surgery for many arterial occlusions. In the past seven to ten years, a very large clinical experience in centers around the world has shown that stenting and angioplasty are preferred as a first-line treatment for more and more processes throughout the body.

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• Loop clip keeps device secured between uses to prevent exposure and contamination

B. Integrated Torquer Device

• Facilitates convenient maneuverability

• Incorporates readily available technique for handling

• Slides and locks onto stent delivery system

C. Unibody Construction

• Combines proximal hypotube + distal flexible segment + strain relief

• Sleek, low profile design delivers flexibility and trackability for ease of use

• All-in-one design allows the operator to maintain complete system control

• Safe and secure for maneuvering through tortuous anatomy

• Hydrophilic coating minimizes friction within the guide and the vessel

• Translates energy and torque directly to tip for true and responsive handling

• The entire Acrobat crimped stent profile compares in size to the crossing profile of the

average pre-dilatation balloon.

• Makes device prep simple, just flush the hoop and go

D. Balloon Control Bands

• Minimizes risk of stent edge injury by greatly reducing the possibility of balloon "dog

boning" during balloon inflation/stent expansion Promotes the “Healthy to Healthy”

stent philosophy

• Contributes to controlled inflation and deflation for optimal balloon utilization

• Helps fold the balloon after stent deployment for ease of catheter retraction past the deployed

stent and into the guiding catheter

Svelte Acrobat Components

A. Luer Hub and Loop Clip

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E. Nylon Balloon

• Capable of high pressure inflation to facilitate direct stenting

• Low compliance provides controlled expansion within the boundaries of the stent Strong

and reliable material makes it capable of multiple inflations

F. Cobalt Chromium Hybrid Stent Design

• Cobalt Chromium (L605CoCr) provides proven eficacy in coronary procedures

• The thin strut design minimizes the risk of vessel injury without compromising radial

strength or radiopacity compared to other Cobalt Chromium stents

• Hybrid stent design with J-link connectors for uniform expansion and enhanced vessel

conformability

G. 22 mm Flexible Coil Wire Tip

• Atraumatic and small (0.012") to minimize vessel contact

• Easily shapeable to facilitate steering and navigation of vessel

• 22 mm length provides effective wire purchase for securing device position

Beijing STT Medical Technology Development Co.

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ABBOTT VASCULAR FOX PLUS PTA CATHETER

MEDTRONIC Balloon Inflation