Impact and penetration resistance of network models of coated lightweight fabric shielding

Abstract

There exist a wide range of applications for lightweight ballistic fabric shields, such as the protection of critical structural components in transport systems and the human body. However, some deficiencies are (1) the susceptibility to being abruptly severed by sharp objects, which completely eliminates the fabric's ability to stretch and absorb incoming kinetic energy and (2) environmental degradation of the fabric due to moisture, heat and sunlight, which is of growing concern, since many new fabrics have multiple purposes, such as electrical and chemical sensing, in addition to being part of a protective system. Because of these issues, the coating of fabric can be advantageous, however, it adds weight to the shielding system. Experiments on this type of coated fabric system are extremely time‐consuming. Accord‐ingly, this paper seeks to develop a computational framework using a coated network model in order to capture the basic characteristics of such systems. One aspect of the model's usefulness is that it can provide qualitative information to guide and reduce costly, time‐consuming experiments. Three‐dimensional numerical examples are given to illustrate the computational model. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical simulations of fabric shields for bulletproof vest: determining the number of sheets to withstand ballistic impacts

“…The rupture of the material Zylon is presented by Zohdi and Powell (2006) and is supposed to occur when the stretch is around ≅ 1.06, see Figure 4. The damage parameter was also proposed by Zohdi (2014c) as shown in the following equation…”

“…This parameter, also called damage representation, was also proposed by Zohdi (2014c) in the following manner…”

“…The contact between a rigid projectile with a fabric shield is performed as a contact point-to-point, i.e., between the fabric node and the projectile, that is described by the position of its center of mass. Basically, according to Zohdi (2010a) and Zohdi (2014c), if penetration of a fabric node into the projectile is detected ("contact"), the following procedures are enacted: (1) move the fabric node to the closest point on the rigid body's surface and (2) if there is friction, then a stick condition is assumed, i.e, assuming a common position and velocity for the point on the surface of the projectile and the fabric node. The friction force is then checked against the static limit, which if violated, enacts a sliding friction force.…”

“…Specially, because there exist a wide range of applications for lightweight ballistic fabric shields, such as the protection of critical structural components in transport systems and the human body. Important works in this field were presented by Zohdi and Powell (2006), Kato, Yoshino and Minami (1999), Pargana (2007) and Zohdi (2014c). In these researches, the authors affirm that some deficiencies are the susceptibility to being abruptly severed by sharp objects, which completely eliminates the fabric's ability to stretch and absorb incoming kinetic energy and the environmental degradation of the fabric due to moisture, heat and sunlight, which is of growing concern, since many new fabrics have multiple purposes, such as electrical and chemical sensing, in addition to being part of a protective system.…”

“…Using the comercial software LS-DYNA this research sought to compare the results obtained by the program developed in this research, verifying the rupture configuration along the time. The final configuration of the ballistic impact experiment, presented by Zohdi (2014c) as a photography, are also used to check the final shape configuration. The yarn is comprised of one-dimensional microscale fibrils, see Figure 1.…”