Objectives

OptiTex Fabric Testing Utility tests the four specific fabric attributes used to design within the 3D environment. If each test is done consistently, you will get a truly clear picture of how your fabric will move in its 3D incarnation.

We developed a Fabric Testing Utility to:
a) Ensure true results of your 3D modeling
b) Reduce your lab testing costs
c) Obtain fabric physical attributes (such as bending, shearing, stretch, etc.) for OptiTex 3D Runway users.

OptiTex FTU and the fabric testing industry standards

Can the FTU teach about fabric parameters?
The FTU has been designed only to provide the user with an appropriate tool to input accurate data into the OptiTex 3D Runway. This machine cannot create fabric standards

OptiTex 3D Runway and OptiTex FTU connectivity

OptiTex’s Fabric testing unit is in place to evaluate, to number (both working units and force units) and to measure the four fabric parameters used in OptiTex’s 3D draping algorithms.

What are the four fabric parameters for both knit and woven materials?

• Bend of the fabric’s own weight (Bending): Measured in units of dny*cm
  Friction (µ): Represents the friction of a given fabric between 0 and 1
  Stretch in X axle and the Y axle (stretching): Measured in units of grf*cm
  Shearing: Measured in units on dny*cm.

The Testing Process

What makes a successful test? What is the level of accuracy of the testing Utility?

Repetition is most important test for OptiTex’s FTU. Success means the same test conducted on the same piece of fabric with only minor differences (a variable close to 0) between the results. The accuracy level of the FTU depends on the user, the size of the fabric sample, and the conditions under which the test is conducted. The FTU is equipped with electronic accessories to assist both with the measurement and the application of a constant force, ensuring consistent accuracy.

How is the testing done?

Fabric is not a homogeneous material, so anticipating how it will react is critical. In addition, all fabrics – whether natural or synthetic – are very sensitive to environmental factors such as moisture and temperature.
Therefore, there are two types of tests:
• The fabric is static and is faces only bending and friction.
• Tests where the fabric is not static and is being stretched and sheared.
When the fabric is not static, the capability to have closer results is harder. However, the FTU automatically corrects for this. We adjust the parameters of the test to the linear field or the linear closeness of the fabric.

The following diagram shows fabric behavior while applying force. The fabrics reaction to the force is nonlinear, but if you reduce the test to a very small field of pressure, you can reach a close linear.
 

The Tests

During testing, the user should use a standard fabric weighing device and a magnifying glass for easy identification of the warp or the weft (knit).

The Bending test

Cut a piece of the fabric (pay attention to the weft direction), place the fabric on the surface outlined with the ruler, and start moving the fabric until part of the fabric is hanging in the air. Once the hanging portion reaches the bottom piece, also lined with a ruler, measure the distance of the fabric. We are looking for the bending value of the fabric based on its own weight.

The Friction test (µ)

Cut a piece of the woven (detail the weft direction), and place it on the special platform, and over it, you place a weight equipped with a sensor. Raise the platform at a regular speed, and once the weight starts to slide on the fabric, the platform stops. The moment the weight started to move is the moment differentiating between the static friction value and the dynamic friction value. Reading the electronic meter allows you to calculate the sliding angle to find the final friction value.

The Stretching test

We are looking for a number measured in units of grf*cm, which defines the relative force different fabrics have both in the x axle and in the y axle. For this, prepare two pieces of fabric – one cut on the weft and once on the warp. Place one of the pieces between the holder on the cart without stretching the fabric. Reset the meter and the weight. Start moving the cart to a defined distance and will the number on the weight. Because the fabric’s resistance to stretching is not linear, measure the fabric’s resistance at three distances to find the average, which will ensure better accuracy. Once you have finished with one piece, repeat the test with the second piece.

The Shearing test

We are looking for a number measured in grf*cm units, which defines the relative force the knit for a cutting movement (forces going in opposite directions) of the fabric. Cut a piece of fabric so the weft thread is at a 45 degree angle. Place the fabric on the cart crosswise and reset the meter and the weight. Start the machine,move the cart to a defined distance and read the weight. 

What are the FTU’s main mechanical parts?

• Encoder – Allows the user to repeat the same tests while maintaining an extremely high accuracy rate, increasing the reliability of the tests.
  A Smart Controller – User-friendly, it controls the meter and adheres to the end controls. It has two modes – automatic and manual.
  End Controllers – The two end controllers allow for easy reset before each test. They maintain the machine’s functionality and ensure long-term work with minimal bugs.
  Packaging – FTU is compact and capable of withstanding travel. The user can take the machine anywhere.
  Servo Motor – The servo-quality allows it to place a measured force on the fabric.
  Electronic weight – The electronic weight supports, is easy to use, and extremely accurate (from 0.05lb at up to 0.005 lb).
  Fabric Clips – The simple and easy to use fabric clips won’t let the fabric go.