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Conventional gear designs are characterized by the meshing teeth which have to accommodate bending loads with a high dynamic load content, together with high contact stresses under a reciprocal sliding. Accordingly, special materials with sophisticated heat treatments, and high fabrication accuracy are required for heavy-duty gears, such as being used in off-road vehicle transmissions The paper describes a novel concept for designing power transmission gears, which eliminates physical sliding between meshing profiles and separates bending and contact loading of the teeth. Geometrical sliding is accommodated by internal shear deformation in specially designed rubber-metal laminates, thus allowing materials with high bulk strength but poor contact properties (aluminum, titanium, fiber-reinforced composites, etc.) to be used for heavy-duty gears.

The flow structure inside the catalytic converter of gasoline engines is very important for consideration of the catalyst light-off condition, converter durability and conversion efficiency. However, the available experimental data under actual engine exhaust conditions are quite limited due to its complicated configuration, critical operating conditions and difficult optical access. Therefore, an experimental study was performed, using laser Doppler velocimetry technique, to measure the velocity distributions inside two production dual-monolith catalytic converters fitted on a firing gasoline engine over several engine operating conditions. This paper reports the normal velocity characteristics measured in a plane 1 mm away from the front surface of first monolith. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline for generating titanium dioxide seeding particles during the engine combustion.

The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain due to impact or inertial loading. However, the mechanical properties of the pia-arachnoid complex and its influence on the overall response of the brain have not been well characterized. Consequently, finite element (FE) brain models have tended to oversimplify the response of the pia-arachnoid complex, possibly resulting in a loss of accuracy in the model predictions. The aim of this study was to determine, experimentally, the material properties of the pia-arachnoid complex under quasi-static and dynamic loading conditions. Specimens of the pia-arachnoid complex were obtained from the parietal and temporal regions of freshly slaughtered bovine subjects with the specimen orientation recorded. Single-stroke, uniaxial quasi-static and dynamic tensile experiments were performed at strain-rates of 0.05, 0.5, 5 and 100 s-1 (n = 10 for each strain rate group).

A high carbon, high silicon and high manganese steel containing about 1% carbon, 3.0% silicon and 2.0% manganese has been developed. This steel has been synthesized using the concepts from Austempered Ductile Cast Iron (ADI) technology. The influence of austempering process on the microstructure and the room temperature mechanical properties of this steel was investigated. The influence of microstructure on the plain strain fracture toughness of this new steel was also examined. Four batches of compact tension and cylindrical tensile samples were prepared from this steel as per ASTM standards E-399 and E-8 respectively. Two batches of specimens were processed by traditional quenching and tempering process while other two batches were austempered. The microstructures were characterized by X-ray diffraction and optical metallography.

Hat sections made of steel are frequently encountered in automotive body structural components such as front rails. These components can absorb significant amount of impact energy during collisions thereby protecting occupants of vehicles from severe injury. In the initial phase of vehicle design, it will be prudent to incorporate the sectional details of such a component based on an engineering target such as peak load, mean load, energy absorption, or total crush, or a combination of these parameters. Such a goal can be accomplished if efficient and reliable data-based models are available for predicting the performance of a section of given geometry as alternatives to time-consuming and detailed engineering analysis typically based on the explicit finite element method.

Commotio Cordis (CC) is the second leading cause of mortality in youth sports. Impacts occurring directly over the left ventricle (LV) during a vulnerable period of the cardiac cycle can cause ventricular fibrillation (VF), which results in CC. In order to better understand the pathophysiology of CC, and develop a mechanical model for CC, appropriate injury criteria need to be developed. This effort consisted of impacts to seventeen juvenile porcine specimens (mass 21-45 kg). Impacts were delivered over the cardiac silhouette during the venerable period of the cardiac cycle. Four impact speeds were used: 13.4, 17.9, 22.4, and 26.8 m/s. The impactor was a lacrosse ball on an aluminum shaft instrumented with an accelerometer (mass 188 g - 215 g). The impacts were recorded using high-speed video. LV pressure was measured with a catheter. Univariate binary logistic regression analyses were performed to evaluate the predictive ability of ten injury criteria.

An experimental method for determining the Instantaneous Frictional Torque (IFT) using pressure transducers on every cylinder and speed measurements at both ends of the crankshaft is presented. The speed variation measured at one end of the crankshaft is distorted by torsional vibrations making it difficult to establish a simple and direct correlation between the acting torque and measured speed. Using a lumped mass model of the crankshaft and modal analysis techniques, the contributions of the different natural modes to the motion along the crankshaft axis are determined. Based on this model a method was devised to combine speed measurements made at both ends of the crankshaft in such a way as to eliminate the influence of torsional vibrations and obtain the equivalent rigid body motion of the crankshaft. This motion, the loading torque and the gas pressure torque are utilized to determine the IFT.

The mechanisms of knee fracture were studied experimentally using cadaveric knees and analytically by computer simulation. Ten 90 degree flexed knees were impacted frontally by a 20 kg pendulum with a rigid surface, a 450 psi (3.103 MPa) crush strength and a 100 psi (0.689 MPa) crush strength aluminum honeycomb padding and a 50 psi (0.345 MPa) crush strength paper honeycomb padding at a velocity of about five m/s. During rigid surface impact, a patella fracture and a split condylar fracture were observed. The split condylar fracture was generated by the patella pushing the condyles apart, based on a finite element model using the maximum principal stress as the injury criterion. In the case of the 450 psi aluminum honeycomb padding, the split condylar fracture still occurred, but no patella fractures were observed because the honeycomb provided a more uniform distribution of patella load. No bony fractures in the knee area occurred for impacts with a 50 psi paper honeycomb padding.

A three-dimensional finite element model of the Hybrid III dummy head-neck complex was created to simulate the Amended Part 572 Head-Neck Pendulum Compliance Test, of the Code of Federal Regulations. The model consisted of a rigid head and five circular aluminum disks joined together by butyl elastomer rubber. Contact surfaces were defined to allow the anterior neck to separate upon an application of extension moments. Two mounting positions, one for flexion and the other one for extension, were used to simulate the head-neck calibration tests. An explicit finite element code PAM-CRASH was utilized to simulate the model dynamic responses. Simulation results were compared to experimental data obtained from First Technology Safety Systems Inc. Model predictions agreed well in both flexion and extension. This model can be used to study the head-neck biomechanics of the existing dummy as well as in the development of new dummies.

The present investigation details an experimental procedure for frontal impact responses of a generic steel front bumper crush can (FBCC) assembly subjected to a rigid full and 40% offset impact. There is a paucity of studies focusing on component level tests with FBCCs, and of those, speeds carried out are of slower velocities. Predominant studies in literature pertain to full vehicle testing. Component level studies have importance as vehicles aim to decrease weight. As materials, such as carbon fiber or aluminum, are applied to vehicle structures, computer aided models are required to evaluate performance. A novel component level test procedure is valuable to aid in CAE correlation. All the tests were conducted using a sled-on-sled testing method. Several high-speed cameras, an IR (Infrared) thermal camera, and a number of accelerometers were utilized to study impact performance of the FBCC samples.

The purposes of this study were to measure the relative linear and angular displacements of each pair of adjacent cervical vertebrae and to compute changes in distance between two adjacent facet joint landmarks during low posterior- anterior (+Gx) acceleration without significant hyperextension of the head. A total of twenty-six low speed rear-end impacts were conducted using six postmortem human specimens. Each cadaver was instrumented with two to three neck targets embedded in each cervical vertebra and nine accelerometers on the head. Sequential x-ray images were collected and analyzed. Two seatback orientations were studied. In the global coordinate system, the head, the cervical vertebrae, and the first or second thoracic vertebra (T1 or T2) were in extension during rear-end impacts. The head showed less extension in comparison with the cervical spine.

This study identified the mechanical properties of ten cadaveric lumbar spines and two Hybrid III lumbar spines. Eight tests were performed on each specimen: tension, compression, anterior shear, posterior shear, left lateral shear, flexion, extension and left lateral bending. Each test was run at a displacement rate of 100 mm/sec. The maximum displacements were selected to approximate the loading range of a 50 km/h Hybrid III dummy sled test and to be non-destructive to the specimens. Load, linear displacement and angular displacement data were collected. Bending moment was calculated from force data. Each mode of loading demonstrated consistent characteristics. The load-displacement curves of the Hybrid III lumbar spine demonstrated an initial region of high stiffness followed by a region of constant stiffness.

This study examined the cervical muscle response to physiologic, high-rate (100 mm/s) tensile facet joint capsule (FJC) stretch. Six in-vivo caprine C5/6 FJC preparations were subjected to an incremental tensile loading paradigm. EMG activity was recorded from the right trapezius (TR) and multifidus (MF) muscle groups at the C5 and C6 levels; and from the sternomastoid (SM) and longus colli (LC) muscle groups bilaterally at the C5/6 level; during FJC stretch. Capsule load during the displacement applications was recorded via a miniature load cell, and 3D capsule strains (based on stereoimaging of an array of markers on the capsule surface) were reconstructed using finite element methods. EMG traces from each muscle were examined for onset of muscular activity. Capsule strains and loads at the time of EMG onset were recorded for each muscle, as was the time from the onset of FJC stretch to the onset of muscle activity. All muscles were responsive to physiologic high-rate FJC stretch.

Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoignition reactions that occur at relatively lower temperatures. In this paper, the role of volatility on the combustion of JP-8 and five different surrogate fuels was investigated in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT is used to determine the derived cetane number (DCN) of diesel engine fuels according to ASTM D6890. The surrogate fuels were formulated such that their DCNs matched that of JP-8, but with different volatilities. Tests were conducted to investigate the effect of volatility on the autoignition and combustion characteristics of the surrogates using a detailed analysis of the rate of heat release immediately after the start of injection.

Simulations using CFD and chemical kinetics models have been applied to gain a better understanding of the effect of the recirculated gases on the autoignition process during cold starting of a direct injection diesel engine. The cranking gases recirculated (CGR) contain fuel vapor and partial oxidation products which affect the autoignition process in different ways. Some hydrocarbons (HCs) species enhance the reaction rates and reduce ignition delay. Meanwhile other HCs species and the partial oxidation products of the autoignition process have an opposing effect. The simulation covered a wide range of the hydrocarbons and aldehydes concentrations and their effect on the ignition delay in a 1.2L Ford DIATA 4-cylinders, water cooled, turbocharged and intercooled diesel engine. The simulated opposing effects of HCs and HCHO on the ignition delay are validated by experimental results at room temperature.

As engine efficiency targets continue to rise, additional improvements must consider reduction of heat transfer losses. The development of advanced heat transfer models and realistic boundary conditions for simulation based engine design both require accurate in-cylinder wall temperature measurements. A novel dual wavelength infrared diagnostic has been developed to measure in-cylinder surface temperatures with high temporal resolution. The diagnostic has the capability to measure low amplitude, high frequency temperature variations, such as those occurring during the gas exchange process. The dual wavelength ratio method has the benefit of correcting for background scattering reflections and the emission from the optical window itself. The assumption that background effects are relatively constant during an engine cycle is shown to be valid over a range of intake conditions during motoring.

Solubility and viscosity predictions for solutions of a thermoplastic polymer with several supercritical gases indicate that significant viscosity reduction and solubility are achieved when the processing conditions are closely matched with the critical properties of the dissolved gas. For the solubility predictions, PVT behavior was modeled by the lattice theory based Sanchez - Lacombe equation-of-state (EOS). Viscosity was estimated by employing the Kelley - Bueche free volume theory coupled with the volumetric calculations of the EOS. Unlike conventional solvents, supercritical solvents add significant free volume to supercritical gas / polymer mixtures; this added free volume provides remarkable viscosity reduction. Viscosity reductions of up to two orders of magnitude are predicted for a supercritical gas / polymer system, compared to the undiluted polymer when the critical temperature for the supercritical gas is matched to the polymer processing temperature.

The influence of calcium treatment on the mechanical properties of a plain carbon steel (SAE 1050) was investigated. The mechanical properties investigated were tensile and impact strength, fatigue crack growth rate, and the fatigue threshold. Impact testing was conducted at both room temperature and at -40°C. Several heats of both calcium and non-calcium treated steel (SAE 1050) were tested in both the as hot-rolled condition and in the quenched and tempered condition (with a hardness level of HRC = 45). The results of this investigation show no significant difference in the tensile properties or room temperature impact properties between the calcium treated and the non-calcium treated steels. However, the impact strengths of calcium treated steels were slightly higher than that of non-calcium treated steels at -40°C.

An experimental study was performed, using cycle-resolved laser Doppler velocimetry (LDV) technique, to characterize the exhaust flow structure inside a catalytic converter retro-fitted to a firing four-cylinder gasoline engine over different operating conditions. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline to generate titanium dioxide during combustion as seeding particles for LDV measurements. It was found that in the front plane of the catalytic monolith, the velocity is highly fluctuating due to the pulsating nature of the engine exhaust flow, which strongly depends on the engine operating conditions. Under unloaded condition, four pairs of major peaks are clearly observed in the time history of the velocity, which correspond to the main exhaust events of each individual cylinder.

An experimental study was carried out to characterize the exhaust flow structure inside the closed-coupled catalytic converter, which is installed on a firing four-cylinder 12-valve passenger car gasoline engine. Simultaneous velocity and pressure measurements were taken using cycle-resolved Laser Doppler anemometer (LDA) technique and pressure transducer. A small fraction of titanium (IV) iso-propoxide was dissolved in gasoline to generate titanium dioxide during combustion as seeding particles for the LDA measurements. It was found that the velocity is highly fluctuating due to the pulsating nature of the engine exhaust flow, which strongly depends on the engine operating conditions and the measuring locations. The pressure oscillation is correlated with the transient exhaust flow characteristics. The main exhaust flow event from each cylinder can only be observed at the certain region in front of the monolith brick.