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The pathomechanics of knee anterior cruciate ligament (ACL) injury related to the female athlete is of high interest due to the high incidence of injury compared to males participating in the same sport. The mechanisms of ACL injury are still not completely understood, but it is known that single-leg landings, stopping and cutting at high velocity are some of the non-contact mechanisms that are causing these injuries. This study analyzed a subject specific analysis of a single-leg drop landing that was performed by a female subject at 60%, 80% and 100% of her maximum vertical jump. The femur, tibia, articular cartilage, and menisci were modeled as 3-D structures and the data collected from the motion analysis was used to obtain the knee joint contact stresses in finite element analysis (FEA). The four major ligaments of the knee were modeled as non-linear springs. Material properties of previously published studies were used to define the soft tissue structures. The articular cartilage was defined as isotropic elastic and the menisci were defined as transverse isotropic elastic. Two different styles of single-leg landings were compared to one another, resembling landing from a basketball rebound. The first landing style, single-leg arms up (SLAU), produced larger knee flexion angles at peak ground reaction forces, while single-leg arms across (SLAX) landings produced higher peak vertical ground reaction forces along with lower knee flexion angles. The mean peak vertical ground reaction force was 2.9–3.5 bodyweight for SLAU landings, while they were 3.0–3.8 for SLAX landings. The time to peak vertical ground reaction force with SLAU landings were 69 ms (60%), 60 ms (80%), and 55 ms (100%); SLAX landings were 61 ms (60%), 61 ms (80%), and 51 ms (100%).Copyright © 2011 by ASME

Wood plastic composites (WPC) are widely used in the industry due to its durability, low cost, and anti-moisture properties in comparison with the natural wood. Recently, WPC are also being considered in musical instrument industry. In this research, we have produced flout shaped WPC samples using African black wood powder and Phenolic resin in a hot compression molding set-up. Initial WPC composites were produced by systematically changing the wood volume fraction. The results showed cracks developed in composites with more than 70% wood. This was related to formation of gas in the system during manufacturing and lack of fluidity in the system to flush the gases. Based on these results the optimum temperature, pressure and wood volume fraction for developing WPC in a form of a flute is developed. A series of experimental procedures were performed to improve mechanical properties of WPC samples by studying the effect short fiber-glass addition to the wood matrix prior to hot pressing. The results showed that the addition of short fiber did not improve the strength of WPC but rather than it reduced its strength compared to unreinforced composite. This was attributed to lack of bonding between short fibers and wood matrix. In contrast encapsulated wood particle composite in an E-glass/epoxy composite sheet before hot pressing showed the mechanical properties of wood composite are enhanced. A two layer unidirectional composite was sufficient for producing flute with desirable mechanical properties. On the basis of the experimental results, a very simple method to enhance the load-bearing capability of WPC which may allow producing reinforced WPC in the form of flout shape is developed.

This study investigated movement combinations which may cause injury to the anterior cruciate ligament (ACL). A 3-Dimensional finite element knee joint model, including bones and ligament bundles, was developed. Bone was modeled as rigid, and a transversely isotropic material was applied to the ligament structures. This study incorporates a novel approach for developing bundle specific prestrain within the ligament structures. The bundles were stretched from their zero load lengths to their reference lengths, producing a strain field mimicking in vivo conditions at full knee extension. A failure locus was created by performing multiple knee joint motion combination simulations until ligament failure. The locus shows which movement combinations of internal/external femoral rotation and varus/valgus angle cause failure within the ACL bundles at 25° of knee flexion. The 3D model provided improved accuracy for locating bundle ruptures. By monitoring stresses and strains within the ligament bundles during knee joint orientation simulations, ruptures were virtually diagnosed. The relationship between knee joint orientation and ligament rupture provides a spectrum for the propensity of ACL injury. The results highlight femoral external rotation relative to the tibia as an important factor related to ACL injury. The results also show the posterolateral bundle to be more susceptible to rupture than the anteromedial bundle. These results have various clinical applications. In sports where ACL injuries are prevalent, training programs can be adapted to address the avoidance of harmful knee orientations. Monitoring bundle rupture locations also increases insight for practitioners in identifying more precise injury mechanisms.Copyright © 2011 by ASME

We studied the stress field and vibration characteristics of functionally graded rotating disks by solving the governing equation of motion using the finite difference scheme. The material was assumed to have a constant Poisson’s ratio with the elastic modulus varying as a power law function of the disk radius. Such a material could be developed by using particle reinforced composites with various reinforcements or reinforcement volume fraction. The results show that the first critical speed of the rotating disk could be increased by using FGMs. The first critical speed is greater for disks having higher elastic modulus at the outer radius. However, the disk may be unstable for certain distribution functions.Copyright © 2010 by ASME

We present a series of analytical models and finite element results (FE) for special 3-D open cellular foam to determine the effective material properties of a 3D rhombic dedecahedron open-cell cellular structure. The analytical approach is based on minimizing the total energy associated with small deformation of a single unit cell of the cellular structure. The finite element models were developed for both a single unit cell and three dimensional foam structure and used to obtain the mechanical properties in all three principal directions.Copyright © 2010 by ASME

From the available biocompatible fibers, glass fibers have drawn the most attention due to their esthetic qualities and easy manipulation. While some investigators have studied the effect of the fibers on mechanical properties such as ultimate strength and fracture resistance of these bio-composites [1], the literature survey reflects that there are very few studies on the wear properties of such fiber-reinforced bio-composites. Thus, the main objective of this study is to investigate the wear characteristics of the fiber-reinforced dental bio-composite. The relationship between fiber weight fraction and fiber length of glass fibers incorporated into a dental resin and the wear resistance of these bio-composites is studied for various applied loads. For comparison, a particle filled bio-composite was also subjected to the wear test. The main objective of this study is to gain some insight into the micromechanisms of wear of these dental bio-composites and their relative performance.Copyright © 2004 by ASME

It is clear that costal cartilage and rib articulation calcification, as well as, weakness of the respiratory muscles reduce the rib cage volume displacement. Usually, calcification begins from costochondral junction and extends toward the sternocostal junction. Teale et al [1] reviewed seven hundred chest radiographs to determine the site and extent of the calcification over an age range of 20 to 90 years. They concluded that the prevalence of the costal cartilage calcification increases from 6% in the 3rd decade to 45% in the 9th and is more common in men. In addition, it is generally assumed that muscle strength decreases 30–40%, between 30 and 80 years of age. The effect of these age-related changes on the respiratory volume change can be realized by studying the transverse and anteroposterior expansion of the ribs during respiration. Here, we try to estimate the respiratory volume change through the changes in the “bucket-handle” movement of the 5th rib utilizing finite element model. The effect of costal cartilages calcification in both transverse and anteroposterior movement of the rib cage can be attained by modeling the total rib cage.Copyright © 2004 by ASME

Sub-surface cracks in pipelines with internal pressure may severely affect their dynamic response. The extreme cases of these cracks are when these cracks go through the thickness of the pipes. Dynamic responses of cracked and un-cracked pipes with fixed ends and under various internal pressures were evaluated experimentally and theoretically. In the experimental part, the effects of pipe internal pressure on the resonant frequencies and damping of the pipe were evaluated. In the theoretical part, finite element analyses were performed to find dynamic response of pipes with various crack length and orientation respect to the axis of the pipe. The experimental results showed resonant frequencies of the pipe are little sensitive to the pipe internal pressure. Similar results were obtained from the theoretical investigations. An axial crack had little effect on the pipe resonant frequencies. In contrast, cracks oriented at an angle to the axis of the pipe had a pronounced effect on some of the resonant frequencies of the pipe. This depended on the crack location in a particular mode shapes. For frequencies where the nodal point of the mode shape was located on the crack region, the frequencies were not significantly affected by the presence of the crack in the pipe. Furthermore, it was observed that the pipe internal pressure had little effect on the resonant frequencies of the cracked pipes.