Modeling and experiments on ballistic impact into UHMWPE yarns using flat and saddle-nosed projectiles

Yarn shooting experiments were conducted to determine the ballistically-relevant, Young’s modulus and tensile strength of ultra-high molecular weight polyethylene (UHMWPE) fiber. Target specimens were Dyneema® SK76 yarns (1760 dtex), twisted to 40 turns/m, and initially tensioned to stresses ranging from 29 to 2200 MPa. Yarns were impacted,...

A new water absorbable mechanical Epidermal skin equivalent: The combination of hydrophobic PDMS and hydrophilic PVA hydrogel

Research on human skin interactions with healthcare and lifestyle products is a topic continuously attracting scientific studies over the past years. It is possible to evaluate skin mechanical properties based on human or animal experimentation, yet in addition to possible ethical issues, these samples are hard to obtain, expensive and give rise...

Celebrating the 100th anniversary of the Stoney equation for film stress: Developments from polycrystalline steel strips to single crystal silicon wafers

Stress in a thin film on a flexible substrate induces a curvature of the substrate. Usually the substrate is orders of magnitude thicker than the film, leading to small and purely elastic deformation of the substrate. In this case, the Stoney equation yields the stress in the film from the measured curvature of the substrate. The Stoney equation...

The role of collagen cross-links in biomechanical behavior of human aortic heart valve leaflets - Relevance for tissue engineering

A major challenge in tissue engineering of functional heart valves is to determine and mimic the dominant tissue structures that regulate heart valve function and in vivo survival. In native heart valves, the anisotropic matrix architecture assures sustained and adequate functioning under high-pressure conditions. Collagen, being the main load...

Adaptation of subchondral bone in osteoarthritis

Osteoarthritis is a chronic joint disease with pathological changes in the articulating cartilage and all other tissues that occupy the joint. Radin and coworkers have suggested the involvement of subchondral bone in the disease process. However, evidence for an essential role in the etiology has never been proven. Recent studies showing reduced...

Relations between rheological properties and network structure of soy protein gels

This paper focuses on the relations between network structure and rheological properties of soy protein gels as a function of pH and ionic strength. Network structure has been characterized independently by permeability measurements and confocal scanning laser microscopy in terms of coarseness. Results showed that gels at pH 3.8 and 5.2 were...

Structure and Deformation Behavior of Nanocomposites Based on Polypropylene and Modified Clays

The effects of the type and concentration of a filler and the ratio of modifier components in the filler on the structure and deformation behavior of nanocomposites based on an isotactic PP and Na+ montmorillonite (a natural clay) modified by various substrates (modifiers) were studied. Upon crystallization of this system from the melt, part of...

Numerical Homogenization of the Rigidity Tensor in Hooke's Law Using the Node-Based Finite Element Method

Combining a geological model with a geomechanical model, it generally turns out that the geomechanlcal model is built from units that are at least a 100 times larger in volume than the units of the geological model. To counter this mismatch in scales, the geological data model's heterogeneous fine-scale Young's moduli and Poisson's ratios have...

Effect of collagen denaturation on the toughness of bone

The purpose of this study was to explore the relationship between the integrity of collagen and biomechanical properties of bone. In this study, age (range, 5-26 years old) and gender related changes in cortical bone samples from 33 baboon femurs (15 males and 18 females) were examined. The percentage of denatured collagen was determined using a...