Table of Contents
Introduction
Fabric Tensile test strength and elongation are important mechanical properties of textile materials. These properties are critical in determining the performance and durability of fabrics in various applications. In this lab, we will determine the tensile strength and elongation of a woven fabric and compare the load-elongation curve with non-woven and knitted fabric.
Materials
- Tensile testing machine
- Fabric samples: woven, non-woven, and knitted
- Scissors
- Marker
- Grips
- Ruler
- Calibration weights
- Data acquisition software
Procedure
- Preparation of the test samples: Cut three fabric samples: woven, non-woven, and knitted, with dimensions of 5 cm x 20 cm using scissors. Mark the center of the sample with a marker to ensure proper alignment during testing.
- Mounting the sample on the tensile testing machine: Attach the grips to the tensile testing machine and adjust the grip separation to 10 cm. Place the fabric sample in between the grips with the center of the sample aligned with the center of the grips. Clamp the fabric in place and ensure that the fabric is aligned straight with no folds or wrinkles.
- Calibration of the tensile testing machine: Before conducting the test, calibrate the tensile testing machine by attaching calibration weights to the grips and adjusting the machine until the readings match the known values of the calibration weights.
- Conducting the tensile strength test: Start the data acquisition software and begin the test. The machine will apply a constant load to the fabric sample, causing it to elongate until it breaks. The software will record the load and elongation data, and generate a load-elongation curve. Repeat the test for each fabric sample.
- Calculation of the tensile strength and elongation: From the load-elongation curve, the tensile strength and elongation of the fabric sample can be calculated. The tensile strength is the maximum load that the fabric can withstand before breaking, expressed in units of force per unit area (N/cm²). Elongation is the percentage increase in the length of the fabric sample before it breaks.
Tensile strength (TS) = Maximum load / Sample area Elongation (%) = [(Final length – Initial length) / Initial length] x 100% - Comparing the load-elongation curve: Compare the load-elongation curve of the woven fabric sample with the non-woven and knitted fabric samples. The load-elongation curve shows the relationship between the load and elongation of the fabric during the tensile strength test. Compare the slope, peak load, and elongation at peak load of the three samples.
Conclusion
In this lab, we have determined the tensile strength and elongation of a woven fabric sample and compared the load-elongation curve with non-woven and knitted fabric samples. Tensile strength and elongation are important mechanical properties that affect the performance and durability of textile materials. By comparing the load-elongation curve of different fabric samples, we can evaluate their performance and suitability for various applications.
What is Fabric Elongation ?
Fabric elongation refers to the ability of a fabric to stretch or lengthen when subjected to external forces or tension. It is a measure of how much a fabric can deform or stretch before it reaches its breaking point. Elongation is typically expressed as a percentage of the fabric’s original length.
Fabrics can exhibit two types of elongation: elastic elongation and plastic elongation.
- Elastic Elongation: Elastic elongation refers to the temporary stretching of a fabric under tension. When the tension is released, the fabric returns to its original shape and size. Elastic elongation is primarily due to the elasticity of the fibers or yarns used to make the fabric. Fabrics with high elastic elongation are often used in applications where stretch and recovery properties are important, such as in sportswear or undergarments.
- Plastic Elongation: Plastic elongation refers to the permanent stretching or deformation of a fabric under tension. Unlike elastic elongation, plastic elongation is irreversible, and the fabric does not return to its original shape after the tension is released. Plastic elongation can occur when the applied force exceeds the fabric’s elastic limit, causing the fibers or yarns to permanently rearrange or break. Fabrics with high plastic elongation are used in applications where strength and durability are crucial, such as in seat belts or heavy-duty fabrics.
The elongation properties of a fabric are determined by various factors, including the type of fibers or yarns used, the fabric’s construction (e.g., weave or knit), and any additional treatments or finishes applied to the fabric. Fabric manufacturers often provide elongation values as part of the fabric’s specifications to help users understand its stretching characteristics and suitability for different applications.
What is Fabric Elongation Testing ?
Fabric elongation testing refers to the process of evaluating and measuring the stretch or elongation properties of a fabric under controlled conditions. This type of testing is conducted to assess the fabric’s ability to withstand tension, determine its stretch characteristics, and understand its performance in various applications.
Fabric elongation testing typically involves the following steps:
- Sample Preparation: Fabric samples are carefully selected and prepared according to specific testing standards or requirements. The samples are typically cut into rectangular or strip-shaped specimens with precise dimensions.
- Testing Equipment: Various testing machines or equipment can be used to perform fabric elongation testing. These may include universal testing machines, tensile testing machines, or specialized fabric testing instruments.
- Test Procedure: The fabric sample is securely clamped or gripped by the testing equipment. Tension is gradually applied to the sample in a controlled manner. The machine pulls the fabric until it reaches a specified point, such as a certain elongation percentage or until the fabric breaks.
- Data Collection: During the testing process, the machine records data such as the applied force or load, elongation or deformation of the fabric, and other relevant parameters. This information is used to calculate elongation values and analyze the fabric’s behavior under tension.
- Analysis and Interpretation: The collected data is analyzed to determine the fabric’s elongation characteristics, including elastic elongation, plastic elongation, maximum elongation before failure, and other relevant properties. The results of the testing can be compared to industry standards or specific requirements to assess the fabric’s suitability for intended applications.
Fabric elongation testing is crucial in various industries, including textiles, apparel, automotive, aerospace, and manufacturing. It helps designers, manufacturers, and researchers understand how fabrics will behave when subjected to tension, enabling them to make informed decisions about material selection, product development, and quality control.
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Frequently Asked Questions | FAQs
What are the 3 types of fabric testing?
Fabric testing involves various methods and techniques to assess the quality, performance, and characteristics of textile materials. While there are numerous specific tests available, three common types of fabric testing are:
Physical Testing: Physical testing involves evaluating the physical properties of fabrics, such as tensile strength, tear strength, abrasion resistance, dimensional stability, pilling resistance, and colorfastness. These tests measure the fabric’s ability to withstand mechanical stress, deformation, and wear.
Chemical Testing: Chemical testing focuses on analyzing the chemical composition of fabrics and determining their chemical properties. This includes testing for the presence of harmful substances, such as heavy metals, formaldehyde, or azo dyes, to ensure compliance with safety and regulatory standards. Additionally, chemical testing can assess factors like pH levels, moisture content, and flame resistance.
Performance Testing: Performance testing assesses how fabrics perform under specific conditions and applications. This includes tests related to moisture management, breathability, water resistance, UV protection, thermal insulation, and electrical conductivity. Performance tests evaluate how well a fabric meets the functional requirements and desired performance characteristics for its intended use.
These three types of fabric testing collectively provide valuable information about the strength, durability, safety, and performance of textiles. Testing protocols and standards, such as those developed by organizations like ASTM, ISO (International Organization for Standardization), or AATCC (American Association of Textile Chemists and Colorists), are often followed to ensure consistency and reliability in fabric testing procedures.
What is tensile strength for fabric ?
Tensile strength is a measure of the maximum load or force a material can withstand without breaking or deforming when subjected to tension or pulling forces. In the context of fabrics, tensile strength refers to the ability of a textile material to resist stretching or tearing when it is pulled in opposite directions.
Fabrics with high tensile strength are generally considered to be stronger and more durable. This property is particularly important in applications where the fabric will be subjected to significant stress or tension, such as in the construction of sails, parachutes, tents, or seat belts. Higher tensile strength allows the fabric to withstand greater forces without tearing or failing.
Tensile strength is typically measured using standardized tests, where a sample of the fabric is subjected to controlled pulling forces until it breaks. The maximum force the fabric can withstand before breaking is then recorded as the tensile strength, usually expressed in units of force per unit area, such as pounds per square inch (psi) or newtons per square meter (N/m²).
What is ASTM for tensile testing of fabrics?
ASTM stands for the American Society for Testing and Materials, now known as ASTM International. ASTM develops and publishes technical standards for a wide range of materials, products, systems, and services. These standards provide guidance and specifications for testing methods, performance criteria, and other aspects related to various industries.
For tensile testing of fabrics, ASTM has published several standards that outline the specific procedures and requirements for conducting such tests. The most commonly referenced standard for tensile testing of textiles is ASTM D5034 – Standard Test Method for Breaking Strength and Elongation of Textile Fabrics (Grab Test).
ASTM D5034 describes a procedure for determining the breaking strength and elongation of woven, knitted, or non-woven textile fabrics using a grab method. The grab test involves gripping a fabric sample between two jaws and applying a steadily increasing force until the sample breaks. The force and elongation at the point of failure are measured to determine the breaking strength and elongation properties of the fabric.
It’s important to note that there are other ASTM standards related to tensile testing of fabrics as well, depending on specific requirements and applications. Some examples include ASTM D5035 (Strip Test), ASTM D2261 (Trapezoid Tear Test), and ASTM D5587 (Grab Test for Seams). These standards provide detailed instructions and guidelines for testing different aspects of fabric strength and performance.