The Stretch Test
Modern day elastic textiles have become the centerpiece for many athletic apparels. One major issue that has arisen in the textile industry is the transparency of the elastic fabrics as they become stretched. The Eclipse Engineering team sought to create a measurement system to quantify and rate elastic fabrics based on how opaque the fabrics became during elongation. The results would rate current fabric samples and assist in development of new fabrics.
The Stretch Test was designed to allow for any elastic fabric to be tested and rated bases on one’s transparency versus stretch. The device offers a two-axis extension platform with simplistic features and repeatable parameters for consistent testing from fabric to fabric. The stretch frame provides structural rigidity through its machined steel assembly.
The first stage of concept development began with identifying the problem. Athletic clothing has become a new and fast growing daily apparel fashion for women. This style of elastic leisure clothing is now worn as outwear much like denim has over the years. Unfortunately, as these flexible materials stretch, their opacity decreases revealing what lies beneath. Research into this issue found that there is not a current repeatable or quantifiable method to detect how fabric becomes more transparent when stretched. Additional investigation found that the fabric’s surface area typically stretched at least 150% in the areas where transparency was most evident. With the problem identified, a design was brainstormed.
Initial concepts focused on two requirements: being able to stretch fabric and measure the light passing through it. Ideas ranged from using counter-weights to hydraulic actuators, until the team narrowed in on a simple and repeatable concept using a pulley and peg-board system.After several iterations, a clamp was designed to be mounted on a horizontal rail-and-carriage system which would easily translate outward in combination with the pulley and notched legs. Paired with an enclosed light box and black box, testing results would remain isolated from external light sources that could alter testing data.
The Stretch Test uses medium grade steel as the centerpiece for the frame and supporting legs. Four Frelon-lined rail-and-carriage systems are placed symmetrically in the x and y axes to provide smooth translation while stretching the fabric. These are paired with strong clamps and notched legs to allow for the attached pins to set a range of elongations. The lower light box extends up to the bottom of the fabric while the upper black box encloses the testing area to ensure ambient light does not skew data during testing.
Verification & Validation
The verification and validation phase of this project was performed to ensure the device met all design requirements and specified customer needs. To do so, a Test Plan document was created in addition to testing the device to ensure all necessities were accounted for.
Testing has indicated measurable effects on opacity when an elastic fabric is stretched. A K-value rating for each fabric is determined by comparing the distance elongated to the lux reading of the light passing through the fabric. In the graph below, a fabric’s results are displayed for three cycles of testing. This fabric’s K-Value was 1.23.
- 20 x 20 x ¼ inch steel base
- 13 ¼ inch tall
- 6 x 6 inch light reading area
- 8 x 8 inch testing fabric
- 8 inch stretch at each axis
- Frelon-lined rail and carriages
- 10 lumen light source
- CEM DT-1309 Lux Meter
After satisfactory testing was conducted, The Stretch Test proved to be a repeatable opacity testing device. Should the device move forward into a serviceable product, the first step would be to test a multitude of different fabric compositions. Should a rating scale such as the K-Value be widely accepted by material consumers, The Stretch Test could become the next industry standard.
Meet the Team
Kelly Bicknell is a Mechanical Engineering student graduating with the Spring 2016 class. She will begin her career as an engineer in San Diego’s booming Defense Industry. Kelly thrives in hands-on and fast paced environments thus making engineering the perfect fit.
Hunter Colodny is a graduating senior Mechanical Engineering student at UNR. He looks forward to a career as a design engineer in either the automotive industry or Department of Defense. Hunter comes from a very mechanical background having driven race cars for 10 years starting at age six. Hunter enjoys doing hands-on activities such as working on automobiles, building, landscaping, and creating models in computer design programs like Solidworks.
Logan Peterson is a senior Mechanical Engineering student at UNR. He is going to study at Western Nevada College after UNR to obtain a Welding degree. Some Logan’s hobbies include rock climbing, acro-yoga, metal art, anything hands-on, and spending time outdoors.
Aaron is a Senior Mechanical Engineering student who will be graduating in the Spring of 2016. He enjoys skiing, biking, and hiking. After graduation, he will be pursuing a career in the outdoor sporting goods industry.
Spencer Kalman is a graduating senior in the Mechanical Engineering department. He will be entering the workforce and beginning his career after graduation. Spencer has an aptitude for conquering every challenge he sets his mind to.