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Volume 1, Issue 4, Summer 2001
LINKS BETWEEN DESIGN, PATTERN DEVELOPMENT AND FABRIC
BEHAVIOR FOR CLOTHING AND TECHNICAL TEXTILES
Sybille Krzywinski, Hartmut Rödel, Andrea Schenk
Dresden University of Technology, Dresden, Germany
ABSTRACT
In this paper is shown the necessity for the development powerful 3D CAD-systems for the textile
and clothing industry. The connection between 2D CAD-systems with 3D CAD-systems enables
the user to prepare a collection more quickly and accurately. Applications could be the drape
behavior of fabrics, the deformational behavior of fabrics when covering defined surfaces and
also technical textiles.
Keywords: CAD-system, simulation, material behavior, close-fitting garments, technical textiles
1. INTRODUCTION • the systems work only in two-
dimensions
For garments the phases of product
development and preparation of production • the material behavior and the material
require approximately triple the time of the parameters are not taken into account.
actual garment life span. In order to
compensate for the resulting greater efforts Both these aspects are required for the three-
in the product preparation and to react more dimensional display of a model with regard
quickly and flexibly to the latest fashion, the to the draping in order to give the designer
use of complex CAD - CAM solutions is and model maker a realistic impression of
essential. Today there are many existing the model. Optimal possibilities to examine
design programs with various software tools the correct fitting and the form of a model
and a wide choice of designing functions. In would be the three-dimensional display of a
connection with sketching-systems so called two-dimensional pattern construction on a
two and a half dimensional presentation dummy or a development of a three-
programs can give an optical impression dimensionally constructed model onto the
how the colors, motifs and materials look on two-dimensional plane, when the specific
a scanned model. Steps of product material parameters are taken into account.
preparation such as pattern construction, Therefore, the more detailed treatment of
grading, pattern planning and pattern physical and mechanical properties and their
optimization and the automated cutting are correct mathematical and physical
realized with computer assistance. However, formulation is of interest [1, 2].
commonly used CAD-systems available on
the market show the following weak points:
Article Designation: Scholarly Works 1 JTATM
Volume 1, Issue 4, Summer 2001
2. THREE-DIMENSIONAL DISPLAY OF the weight per unit are considered in the
TWO-DIMENSIONAL PATTERN draping module (Figure 2; Table1).
The scale of the property curves depends on
The current procedure to create patterns is a the measurement devices.
multi-step approach which involves much
personnel, time and costs due to the trial and
error phase. The fabric properties enter the
design process only via expertise of
designers. It is absolutely necessary for
CAD-systems to be extended to material
parameters and further search for
possibilities to connect design and pattern
construction more closely in the future [3, 4,
5].
The objective of the research is to create a Figure 1: Comparison: Designer Sketch
complete CAD-system for garment and Simulation of Skirt
manufacturers including 3D visualization of
garments on virtual human beings. An
excellent CAD-system for the clothing
industry should be comprised of the
following modules:
• a fabric library correlating easily
determined fabric properties to fabric
drape configurations; search and sorting
routines should be integrated in the library
for efficient retrieval of information;
• a model for the human body, which can be
adapted for persons of different sizes;
• routines to simulate garment patterns from
specific fabrics on the human body using
data from the fabric library.
The following figures, which were made
using DesignConcept 3D [8] by CDI
Technologies Ltd. (recently acquired by
Lectra Systemes, France), give an
illustration of such a CAD-system. The
Figure 2: Fabric Properties
software DesignConcept 3D is based on the
polygon computation of NURBS (Non-
Uniform-Rational-B-Splines). It is Properties Parameters [Unit]
considered the state-of-the-art computation Tensile Warp LT
method for designing complex polygon Weft WT [ gf cm / cm2 ]
surfaces. Figure 1 shows a comparison Warp 45° RT [ % ]
between a sketch by a designer and a Warp 135 °
simulation of a skirt. Bending Warp B [ gf cm2 / cm ]
Weft 2HB [ gf cm / cm ]
In this software program the bending Weight W [mg / cm2 ]
properties in warp and weft direction, the Thickness T [ mm]
tensile properties in warp, weft , 45 degree
warp and 135 degree warp direction and also Table 1: Used Properties
Article Designation: Scholarly Works 2 JTATM
Volume 1, Issue 4, Summer 2001
A prerequisite for the simulation process is
the two dimensional pattern piece (Figure
3). They can be prepared with conventional
2D CAD-systems.
Figure 5: 2D Pattern with Guidelines and Seams
The next step is to position the 2D mesh into
the 3D space near the 3D body, from which
the draping process starts (Figure 6).
Figure 3: Two Dimensional Pattern
Companies have developed 3D body-
scanners where the three dimensional
perception of the human body can be
realized with a sensor system in a quick and
objective way (Figure 4).
Figure 6: Start Position
After this, the user has to generate a surface
from the draped mesh. The surface can
covered with different colors and/or designs.
Figure 7 shows different examples.
Figure 4: Human Body
The DesignConcept 3D enable the user to
seam 2D pattern pieces together and drape
them over a 3D model. Therefore, it is
necessary to prepare the 2D pattern piece.
Guidelines are used to anchor special lines
(for example the neckline or waistline) to Figure 7: Examples of Draped Surfaces
the 3D body and seam points match
different pattern pieces (Figure 5).
Article Designation: Scholarly Works 3 JTATM
Volume 1, Issue 4, Summer 2001
Disadvantages include the high and direction from 1.5 to 2 N per 5 cm fabric
expensive hardware demands and long width (for underwear, for instance) but it is
calculation times (in some cases, up to some also possible to use other tensile force
hours). values (for example, for clothes with a high
pressure effect) [6].
3. FIT OPTIMIZATION FOR CLOSE
FITTING GARMENTS With the help of powerful software the
In the mechanical consideration of designer is in the position to create an
deformability of fabrics, two directions are accurate 2D pattern from 3D model surfaces
distinguished. The first one deals with drape for close fitting body shapes.
behavior of the fabric and the second one is
the deformational behavior of fabrics when Problems which are characterized by large
covering defined surfaces. This application deformations may be described by
requires a nearly wrinkle-free draping of the incremental formulations to determine the
fabric, such as close-fitting garments. state of deformation and tension stress. For
this purpose, a mesh is generated on the
For close-fitting garments like underwear, component surface to be shaped. The mesh
sportswear and swimwear, there are high may be generated automatically or
demands towards fit and pattern interactively. The accuracy of computation
construction. The garment size has to be depends on the triangle size. Material
adjusted exactly to the human body, while behavior is attributed to the mesh to
ensuring optimal comfort and freedom of simulate the development in the two-
movement. In pattern construction for close- dimensional plane, depending on the used
fitting elastic clothing, usually the girth material. First, UV-curves have to be drawn
measurements of the garment are configured directly on surfaces (Figure 9). Each point
to be smaller than the body measurements so on a UV curve has a U and V coordinate,
that the material stretches when worn. just like each surface point. When the
Consequently, not only body measurements, surface is modified, any UV-curves on the
but also mechanical properties of the fabric surface also change.
crucially influence the garments fit. The
extensibility, i.e. the force - extension
relation in case of tensional strain with the
corresponding modules, is a significant
material parameters. (Figure 8).
5,0
4,0
3,0
warp
Force N
weft
2,0
1,0
0,0
0,0 5,0 10,0 15,0 20,0 25,0 30,0 35,0 40,0 45,0 50,0 55,0 60,0
Extension %
Figure 8: Force-Extension Relation
Figure 9: Curves on 3D Surfaces
Investigations into wearing strain on knit
clothing show that wearing comfort is
optimal when stretching the material in girth
Article Designation: Scholarly Works 4 JTATM
Volume 1, Issue 4, Summer 2001
With the region function, it is possible to
create accurate 2D pattern pieces from 3D
model surfaces. Regions in 3D grow over
model surfaces, conforming to surface
contours and crossing the boundaries of
adjacent surfaces as directed (Figure 10).
Once a 3D region is created on a surface
model, it may be “flattened” to produce a
2D region counterpart.
Figure 11: Flattening Process
Figure 10: Regions on Surfaces
The next step is to apply the mechanical
properties of the knit fabric to a 3D region
mesh. The simulation process is an
advanced flattening technique that
determines deformation strain, stress and
develops a mesh from 3D to 2D based on
the mechanical properties applicable to the
grain and cross directions. The stress or
strain analyses colors show the 3D mesh
stress or strain based on the development Figure 12: Visualization of the Realistic Appearance
status of the 2D mesh (Figure 11).
In terms of visualization, one can apply 4. TECHNICAL TEXTILES
material properties and map to regions in
order to enhance the realistic appearance of Textile reinforced light weight structure offer
a model (Figure 12). For example, if you significant advantages among others in
apply a patterning fabric image to a 2D automobile and aircraft construction,
pattern, the “stripes” appear on the especially for the design of curved
associated 3D surface just like they appear components. This is achieved when textile
on the pattern, regardless of the orientation reinforcing structures, which can be arranged
of the 3D surface. and combined very flexibly, are specifically
draped. Owing to insufficient design
experience and the high cost of material, the
potential fields for application in particular in
Article Designation: Scholarly Works 5 JTATM
Volume 1, Issue 4, Summer 2001
mechanical engineering and the auto industry shape according to the required load and
have not been explored. thus avoiding rework (Figure 13).
At present, after the structural element has Three-dimensional CAD programs are
been designed, the desired design variant is mainly applied to design complex
implemented in several iterations. As a components (AUTOCAD 2000,
result, the development of the structural CATIA.)[9,10]. The data obtained by the
element most frequently takes a rather long above remarks programs may be transferred
time and involves considerable costs. In to the simulation program via suitable
order to guarantee the required variety of interfaces (IGES- Initial Graphics Exchange
models and to make the structural Specification, VDAFS – interface suited for
component adequate for loading, without at the exchange of free forms and curves) [8,
the same time increasing the involved time 9].
for industrial engineering, the development
of efficient tools for product simulation is of
predominant importance.
Since 1997 a research team supported by the
German Research Foundation (DFG) has
been working at Dresden University of
Technology under the headline Textile
Reinforcements for High-Performance Rotors Figure 13: 3D component
in Complex Applications [7].
The textile preform should be in most exact
4.1 Textile Preform accordance with the component geometry
The following steps are necessary to make a desired. In particular, for the realization of
textile preform with the component design free-form surfaces, it is necessary to cut the
being very complex: fabric or multiaxial structures so that it may
! pattern design in accordance with be shaped later without irregular folds. After
material behavior the patterns have been developed with
! cutting regard to functional requirements using a
! stacking three-dimensional model, surface generation
! prefabrication and placing of the z and the development of the two-dimensional
reinforcement patterns are made feasible by an efficient
! assembly of the 3D preform software tool (Figure 14).
Most of the components may be produced
using various procedures. Material
considerations, design and economic aspects
should determine the procedure chosen.
4.2 Pattern Construction under
Consideration of the Material
Behavior
If curved element contours of lightweight
textile structures are covered with an
undefined shape of the reinforcing textile,
the mechanical component properties may
deteriorate. The patterns should be Figure 14: Conical shell – shearing of a
developed directly on the object to apply the carbon fabric
reinforcing structures to the desired 3D
Article Designation: Scholarly Works 6 JTATM
Volume 1, Issue 4, Summer 2001
Shearing in the pattern as well as material 5. CONCLUSIONS
tension stresses and stretching may be
analyzed to provide the designer with The working methods outlined in this
information that enables one to produce research can assist designers with work and
suitable patterns from the reinforcing textile also enable designers to deal with the
material. implementation of designs in view of pattern
construction, without limiting creativity.
The material data obtained for the shearing,
the material tension stress and also the 6. REFERENCES
stretching behavior may be implemented in
the simulation program by scanning the [1] Schenk, A.: Berechnung des
measurement curves and subsequent scaling Faltenwurfs textiler Flächengebilde,
or by loading a file in the ASCII format Dissertation TU Dresden, 1996.
[11]. This investigation starts from an [2] Brummund, J.; Schenk, A.; Ulbricht,
orthotropic structure for the majority of V.: Beitrag zur Modellierung des Fall-
fabrics tested. When high modulus carbon verhaltens in der Textilindustrie,
yarns are processed (E modulus > 650.00 Proceedings GAMM 1998, Bremen,
N/mm2), a starting point is the knowledge Germany.
that of potential deformation between the [3] Krzywinski, S.: Design und
two-dimensional cutting and the multicurved Materialverhalten – Gestaltungseinheit
component surface results from the shearing zur Schnittentwicklung, Mittex 4/1999,
deformation. After the computation has been S.9-11.
completed, the shearing in the shaped [4] Krzywinski, S.; Rödel, H.; Schenk, A.:
patterns may be analyzed. A comparison Design und Materialverhalten – Gestal-
with the critical shearing angle, which tungseinheit zur Schnittentwicklung
indicates how far the share of threads can be DWI Reports 2000, S. 182-189.
twisted or compressed without folds, helps [5] Krzywinski, S.: Design und Material-
the designer to decide if the pattern is suited verhalten, Bekleidung und Wear
for the component surface. (2000)3, S. 12-17.
[6] Kirstein, T.; Krzywinski, S.; Rödel, H.:
Another sample product is a spherical Pattern construction for close-fitting
segment (Figure 15). One can see the garments made of knitted fabrics
developed pattern and also get information Melliand English 3/1999, S. E 46 - E
about its behaviors. For the flattening 48.
process, a shear angle of approximately 40 [7] Krzywinski, S.; Herzberg, C.; Rödel,
degree is necessary. H.: Computer-aided product
development and the making-up of
multilayer 3D-preforms for composites,
AUTEX CONFERENCE, Technical
Textiles, Juni 2001, Portugal.
[8] Reference Manual DesignConcept3D,
Volume II, Grand Rapids, 1996.
[9] Reference Manual AUTOCAD 2000,
San Rafael, CA
[10] CATIA Dassault Systems, 2001,
http://www.catia.com
[11] ASCII, Joan G. Stark, 2001,
http://www.ascii-art.com
Figure 15: Spherical Segment
Article Designation: Scholarly Works 7 JTATM
Volume 1, Issue 4, Summer 2001
Prof. Dr.-Ing. habil. H. Rödel, Technische
Universität Dresden, Institut für Textil- und
Bekleidungstechnik, D-01062 Dresden,
Deutschland,
Tel.: +351/4658 267, Fax: +351/4658 361,
E-Mail: roedel@tud-itb.ipfdd.de
Dr.-Ing. S. Krzywinski, Technische
Universität Dresden, Institut für Textil- und
Bekleidungstechnik, D-01062 Dresden,
Deutschland,
Tel.: +351/4658 359, Fax: +351/4658 361,
E-Mail: krz@tud-itb.ipfdd.de
Dr.-Ing. A. Schenk, Technische Universität
Dresden, Institut für Textil- und
Bekleidungstechnik,
D-01062 Dresden, Deutschland,
Tel.: +351/4658 359, Fax: +351/4658 361,
E-Mail: schenk@tud-itb.ipfdd.de
Article Designation: Scholarly Works 8 JTATM
Volume 1, Issue 4, Summer 2001
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