Research On Biaxial Tensile Properties Of Warp Knitted Fabric

Warp knitted fabric was used in many more areas,such as garments,decoration,industry and so on. In order to design knitted fabrics which meet with the requirements of texture, we have to know the mechanical properties of fabrics theoretically at first. The tensile properties is very important to evaluate the mechanical properties of fabric and most of researches focus on one-way stretch. However, biaxial tensile can describe the tensile properties more accurately. For the application limit of the instrument, there was rare research in the fabric biaxial tensile home and abroad. As for the warp-knitted fabric, those researches are much less. This paper is to investigate that how the tensile speed, the way of tension and the fabric structure influence warp-knitted fabrics' biaxial tension properties. Furthermore, it is used to establish the standard for the two-way tensile and provided basics comprehensive assessment whether fabrics are damaged easily under extremely complicated conditions.First of all, it will result in deviation of the testing condition if the specimen slips in the clamp. In order to prevent slipping, different kinds of materials were added in the chuck and the best one was selected. It turns out that sticking the abrasive paper on the place where the specimen is clipped by the clamp and also letting it be covered by double sided adhesive tape can not only prevent the strength of specimen from being improperly reduced but also prevent the specimen from slipping effectively.Then, this paper investigated how the tensile speed influences their biaxial tension properties. The tensile fracture mode involves fixed one tensile direction then moved the opposite clamps that gripping the fabric or moved all the four clamps that gripping the four edges of the fabric. When moved all the clamps, the tensile speed of the opposite clamps could be the same or different. Through researching the indexes including the breaking strength, breaking extension, stretch modulus and work of rupture, it will found the trends of the tensile speed influenced mechanical properties of warp-knitted fabric under biaxial tensile.Next, the paper studies how the drawing direction influences the properties of warp-knitted fabric under biaxial tensile. Based on the two-dimensional loop structure, we analyzed and calculated how the bear segments of the loops influence the breaking strength. Finally using fitting method, it's found that there were polynomial relations between tensile properties and loading directions which will help forecast various index under actual use.Finally, the paper studies the properties of five kinds of fabrics under biaxial tension. Based on the comparison with specific tensile strengths,specific modulus breaking extension and specific breaking work of fabrics with different structures,the paper draws a conclusion on what difference of the two-way drawing between the single tricot warp knitted fabric and double tricot warp knitted fabric.What is more, the mechanism of the two-way drawing was also discussed.