Eva Zajícová Technical University of Liberec

Eva Zajícová Technical University

of Liberec

Eva Zajícová, KAM, FM, TU Liberec

Ještěd – 1012 m

The museum The theatre

The town hall Eva Zajícová, KAM, FM, TU Liberec

Technical University of Liberec

The university consists of six faculties:

●Faculty of Mechanical Engineering (1953)

●Faculty of Textile Engineering (1953)

●Faculty of Education (1990)

●Faculty of Economics (1992)

●Faculty of Architecture (1994)

●Faculty of Mechatronics and Interdisciplinary Engineering Studies (1995)


●department of electronics and signal processing

-laboratory of computer speech processing●department of software engineering

-laboratory of robotics●department of electrical engineering●department of measurement

-laboratory of diagnostics and signal processing●department of control engineering●department of modelling of processes ●department of applied informatics ●department of electromechanical systems

Faculty of Mechatronics


Department of Measurement

●analog and digital measurement instruments analog and digital measurement instruments

●automated digital measuring systems automated digital measuring systems

●computer control of experiment and measurement process computer control of experiment and measurement process

●digital signal processing applications digital signal processing applications

●technical diagnostics technical diagnostics

●measurement of electric and non-electric quantities measurement of electric and non-electric quantities

●optical measurement methods - laser anemometry, visualization, optical measurement methods - laser anemometry, visualization, interferometry interferometry

●computer image processing computer image processing

●photonics photonics Eva Zajícová, KAM, FM, TU Liberec

Prof. Jaroslav Nosek, M.Sc., Ph.D.

ICPR - the International Center for Piezoelectric Research has been established as a research center of the University with the additional aim to provide a contact milieu of industrial companies involved in the development and production of electromechanical materials and devices. ICPR will be glad to consider and perform research for organisations involved in the production of piezoelectric materials or electromechanical devices.

Coordinator for the study stay in abroad (in Ensait)Director of ICPRProfessor of physicsDeptartment of Electrical Engineering and Electro-mechanical SystemsTechnical University of Liberec

http://www.fm.vslib.cz/htm/fakulta/icpr.htm


My doctoral thesisMy doctoral thesisthe methods of the measurement of forces the methods of the measurement of forces

in oblique cut fabrics for uniaxial deformationsin oblique cut fabrics for uniaxial deformations


●The creation of mathematical model for the evaluation of the dimensions of forces – not weaved (one plane warp, one plane weft)

●The project of the measuring method for the acting forces in the fabrics

●The measurement of tensile and shear forces in the fabrics with the ‘ordinary’ weave

●The measurement of oblique cut fabrics in the full spectrum of angles (0° - 90°)

●The graphic of processing of signals from sensors

tan

cos

dx

dl

2

2

1

221

sin

cos

tan

tu

to

o

t

l

ll

dddl

Calculation of elongation threads εo and εu

where:l – the length of theardd – the length of samplex – the width of sampleεo - elongation warp threads εu - elongation weft threadsεt – elongation the fabric


Determination of forces in warp and weft threads and number of threads on given with of fabric

cos

cos2

b

an

SEF

o

to

sin

sin 2

ba

n

SEF

u

tu

For warp thread:

For weft thread:

where:

E - Young’s modulus

S - thread area.

εt – elongation the fabric

a - width of the fabric

b - distance of threadsEva Zajícová, KAM, FM, TU Liberec

Acting forces in horizontal and vertical direction

4sin4

cos

sin

21

2

1

b

aSEF

nFnFF

FF

FF

ts

uos

u

o

2sin21

1

sin

cos

2

43

4

3

b

aSEF

nFnFF

FF

FF

tT

uoT

u

o When:

sin 4 α = 1 then Fs is max

sin α = 0 or α = 90° then Ft is max

Ft max is 4 times greater then Fs max

In real fabric the force is a little bit lower because there will be acting for example a way of interlacing threads, it is structure of fabrics.


How measure the shear force?How measure the shear force?

●Unfasten one jaw to provide Unfasten one jaw to provide her horizontal variationher horizontal variation

●Put the jaw on the metal strips Put the jaw on the metal strips –the dimension and the number –the dimension and the number of strips is given the of strips is given the dimensions of the tensile force dimensions of the tensile force (the strips mustn't be plastic (the strips mustn't be plastic deformed)deformed)

●Put the sensor (tensometer) at Put the sensor (tensometer) at the jaw and scan the horizontal the jaw and scan the horizontal variationvariation


Relation between average tensile force and elongation Relation between average shear force and elongation

Tensile forceTensile force

Shear forceShear force


The measurement of tensile and shear force for the samples of fabrics 0°- 90°

The project goalsThe project goals

●Find the optimum possibility how to measure the shear Find the optimum possibility how to measure the shear force, without losing any force (the force, which is used on force, without losing any force (the force, which is used on the friction)the friction)

●The measurement of the tensile and shear forces directly The measurement of the tensile and shear forces directly on the tested fabrics is ideal, because it doesn‘t have the on the tested fabrics is ideal, because it doesn‘t have the problems with the transfer forcesproblems with the transfer forces

●The measurement of the tensile and shear forces at the The measurement of the tensile and shear forces at the same moment has the same sampling rate by both sensorssame moment has the same sampling rate by both sensors

●The elementary data processingThe elementary data processing



My work – in Ensait

The former work in GEMTEX was on the characterization of the monofilament and the multifilament. Our idea is to find the relationship between the monofilament and the multifilament.

Therefore is the need:

●Find the ideal speed on the testing of samples (for the fibers and the yarns)

●Find the optimum length of sample (according to the possibilities the machine)

●Find if the twist affect the process or no

The measurement of title and diameter

Polypropylene

●for one fibre: title - 23,19 dtex diameter – 58,5 μ m● for yarn: title - 185,5 tex diameter – 523,24 μm

Polyester

●for one fibre: title – 21,06 dtex diameter – 50,4 μ m●for yarn: title – 168,5 tex diameter – 450,836 μ m



The measurement of fibers with the constant speed


The measurement of polypropylene yarns with the different twist


The measurement of polyester yarns with the different twist

More information is on website:More information is on website:

www.douillet.info/~zajicovawww.douillet.info/~zajicova


Documents

Eva Zajícová Technical University of Liberec