Fabric thermostamping process

Formed parts resulting from the thermostamping process using Twintex (a) balanced plain-weave fabric and (b) unbalanced twill-weave fabric. 

The thermostamping process is dominated by the fabric architecture. Currently, most of the pure and hybrid woven fabrics used in textile composites are simple 2D fundamental weaves, that is, plain, twill and satin weaves, which are identified by the repeating patterns of the interlaced regions in the warp and weft directions. The plain weave is one of the most commonly used basic reinforcements for woven-fabric composites. In a plain-weave structure, one weft yarn goes over and under warp yarns as shown in Hg. 6.2. In a twill-weave structure as shown in Fig. 6.8a, each warp yam is woven over two consecutive weft yarns and under the following two weft yarns. The UC of a twiU-weave fabric is shown in Fig. 6.8b. The satin-weave fabric has good drapability, with a smooth surface and minimum thickness. One warp yarn is woven over N(N>2) successive weft yarns and then under one weft yarn. This weave structure is called an (N + l)-harness satin weave. The satin-weave fabric as shown in Fig. 6.9a is a 4-haraess satin-weave fabric, and the associated UC is shown in Fig. 6.9b. 

To reduce manufacturing cost and time and to achieve an acceptable composite design without expensive prototype testing, it is desirable to simulate the thermostamping process. There is currently no widely accepted modeling approach that can accurately capture all the important aspects of fabric deformation and effectively predict both the macroscopic mechanical response of the fabric as well as the response of the yarns at the meso-structural level. Specialized models employing various approaches have been proposed. 

Any future improvements in the use of the thermostamping process will require developing further the theory of the mechanical behavior of fabric... 

Unfortunately, most traditional continuum models proposed in the literature do not account for the effects of the interactions between the yarn families, such as locking, resistance to relative yarn rotation and change in the load path direction with the yarn rotation. Locking and yarn rotation are the dominant mechanisms for the response of the fabric to in-plane shear, which is the major deformation mechanism during the thermostamping process. Thus, the continuum models may lose the capability to simulate potentially important behaviors in some fabric applications where both the macroscopic behavior at the continuum level and the yarn interactions at the mesostructural level may be important. 

Gamache, L. (2007), The design and implementation of a friction test apparatus based on the thermostamping process of woven-fabric composites , MS Thesis, Department of Mechanical Engineering, University of Massachusetts Lowell. 

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