Anthony J. Paris

Accelerations of the Head During Soccer Ball Heading

The objective of this study was to investigate the accelerations of the head during soccer ball heading by introducing a prototype accelerometer-chip instrumented mouth guard. This mouth guard was evaluated for further use in head impact studies.Copyright

Bending of Two-Ply Cord Composite Cylindrical Shells

Abstract The load-displacement behavior of two-ply laminate cord composite cylindrical shells was quantitatively and qualitatively assessed with an emphasis on the effect of cord-ply angle. An equilibrium approach was used to develop the load-displacement model that took into account the mechanics of the matrix, the cords, and the shell. The load-displacement results for a two-ply laminate cord composite cylindrical shell typical of what can be found in steel-belted radial tires were presented. Those results illustrate that the shell behavior depends upon the loading and the unique combination of the cord-ply angle, cord extension-twist coupling and large axial stiffness, rubbers small elastic modulus and large Poissons ratio, and small cord volume fraction.

Elasticity Approach to Load Transfer in Cord-Composite Materials

An elasticity approach to the mechanics of load transfer in cord-reinforced composite materials is developed. Finite cords embedded in an elastic matrix and subjected to axial loading is considered, and the extension-twist coupling of the cords is taken into account. Closed form solutions for the axial force and twisting moment in the cord, the shear stresses at the cord-matrix interface in the axial and circumferential directions, the effective axial modulus of the cord, and the apparent modulus of the cord composite are presented. An example of a cord composite typical of what can be found in steel-belted-radial tires is used to illustrate the results. It was found that large shear stresses occur at the cord-matrix interface in both the axial and circumferential directions at the cord ends and that the effective modulus of the cords may be greatly reduced. As a result, the apparent modulus of the composite may be significantly less than that found by a conventional application of the rule-of-mixtures approach.

Respiration mode detection using a wireless instrumented mouthguard

Many ongoing research and commercial efforts seek to develop head-mounted sensor systems primarily intended to measure the severity of impacts to the head and body. The majority of these systems incorporate computational and data acquisition electronics close to the mouth or ears. The prospect of utilizing such devices for health and safety assessment during athletic, occupational, and recreational activities presents a unique opportunity to use these systems for additional physiological monitoring and detection. In particular, instrumented mouthguards provide access to bone, mucosa, arteries, saliva, and inspirated and expirated air. We have developed an instrumented mouthguard with a primary function of inertial measurement of the skull, but present a secondary functionality of measuring respiration using a simple palate impedance measurement capable of identifying respiration rate and respiration mode.

An Instrumented Mouthguard to Measure Head Accelerations Due To Impact

In the long term, quantitative measurements indicating the magnitude and nature of head impacts will be essential to understanding the biomechanics of head injury. Tools are needed that can quantitatively measure the levels of head acceleration experienced by athletes in a variety of situations in order to assess these risks. The current research is aimed at developing instrumentation that is comfortable enough to use in the field and which can measure head accelerations from blows to the head repeatably and accurately. Soccer is a unique sport in that the unprotected head is deliberately used to direct the motion of the ball during play, which makes it practical to study in a controlled laboratory setting. While the possible long-term effects of heading are still subject to debate [1,2], there is evidence which suggests that it is responsible for transient neurocognitive deficits [3] and transient concussion symptoms [4].Copyright

Fatigue Behavior of Stainless Steel, Titanium, and Cobalt Chromium Molybdenum Spinal Rods

The objective of this study was to measure and compare the fatigue behavior of 316L stainless steel, titanium (Ti-6Al-4V), and cobalt chromium molybdenum (CoCrMo) spinal rods in vitro. Spinal rods are used to immobilize the spine while fusion of the vertebrae occurs (spinal arthrodesis). Implanted spinal rods are subjected to cyclic loading and are therefore susceptible to fatigue failure if fusion does not occur sufficiently quickly. A significant number of spinal rod fatigue failures have been observed between six months to one year following surgical implantation. On average, the spine will experience about 3 million cycles per year. Stress overloads can result in permanent deformation or immediate failure of the rod, however these overloads are seldom the root cause of failure—rods typically fail by fatigue [1].Copyright

Soccer Ball Heading Model

Increasing attention on health and safety has brought attention to the possible cumulative head trauma of soccer ball heading. Attempts to study the correlation of neurocognitive deficits with heading, the acceleration of the head during heading, and the effectiveness of soccer headgear have appeared in the literature [1–7]. Lacking was an analytically based, experimentally verified biomechanics model of the impact between the soccer ball and the head. Such a model was attempted here. Figure 1 shows (a) a drawing of the impact at time t used to develop the theoretical analysis and (b) the solid resin sphere and fixture, soccer ball, and force plate experimental apparatus.Copyright