This paper describes the methodology and reports the results of detailed thermomechanical nite element analyses of cast iron brake discs under repeated high g braking conditions. The thermal analysis allows for heat loss from the vanes in a back-ventilated disc design as well as heat transfer to other parts of the brake assembly. The cast iron material properties required for the non-linear structural analysis are generated by mechanical tests on samples cut from the brake disc. The material model developed by the authors allows for the variation of ow stress with temperature and for the diVerent yield properties of cast iron in tension and compression. The nite element results, derived from a preliminary investigation, indicate regions of high plastic strain accumulation which may lead to disc crazing and/or cracking and enable comparisons to be made between back-and front-vented rotor designs.
Realistic driving cycles for Thailand's road conditions were studied only for the pollution problems of passenger cars and light-duty trucks in urban areas of the metropolitan region. Such driving cycles did not cover rural areas and the in-use operation of buses. Furthermore, such created methods of the driving pattern were very irregular and complicated for chassis dynamometer operation. To propose a new method for a realistic driving cycle, the development of the route traffic for bus transportation in rural areas using a time series clustering technique is indicated. As a case study, this method was applied to collect the driving data on the 323 route in Kanchanaburi province using on-board measurement. The selection procedure of suitable speed and interval time for driving cycle construction was revealed. Similarity of driving characteristics was identified with clustering technique for each time duration to decide the best driving cycle. In conclusion, the frequency of speed ranges from entire trips is 30-40 km/h with the highest ratio of deceleration time to the entire trip. Furthermore, discrete average speeds at each time point with 40 seconds of interval time are the best choice related to the real driving condition in this case study.
Objective: Traffic fatalities among motorcycle users are intolerably high in Thailand. They account for 73% of the total number of road fatalities. Children are also among these victims. To improve countermeasures and design of protection equipment, understanding the biomechanics of motorcycle users under impact conditions is necessary. The objective of this work is to analyze the overall kinematics and injuries sustained by riders and child pillion passengers in various accident configurations. Methods: Motorcycle accident data were analyzed. Common accident scenarios and impact parameters were identified. Two numerical approaches were employed. The multibody model was validated with a motorcycle crash test and used to generate possible accident cases for various impact conditions specified to cover all common accident scenarios. Specific impact conditions were selected for detailed finite element analysis. The finite element simulations of motorcycle-tocar collisions were conducted to provide insight into kinematics and injury mechanisms. Results: Global kinematics found when the motorcycle's front wheel impacts a car (config-MC) highlighted the translation motion of both the rider and passenger toward the impact position. The rider's trunk impacted the handlebar and the head either impacted the car or missed. The hood constituted the highest head impact occurrence for this configuration. The child mostly impacted the rider's back. Different kinematics were found when car impacted the lateral side of the motorcycle (config-CM). Upper bodies of both rider and child were laterally projected toward the car front. The windshield constituted the highest proportion of head impacts. The hood and A-pillar recorded a moderate proportion. The rider in finite element simulations with config-MC experienced high rib stress, lung strain, and pressure beyond the injury limit. A high head injury criterion was observed when the head hit the car. However, the simulation with config-CM exhibited high lower extremities stress and lung pressure in both occupants. Hyperextension of the rider's neck was observed. The cumulative strain damage measure of the child's brain was higher than the threshold for diffuse axonal injury (DAI). Conclusions: This study revealed 2 kinematics patterns and injury mechanisms. Simulations with config-MC manifested a high risk of head and thorax injury to the rider but a low risk of severe injury to the child. Thorax injury to the rider due to handlebar impact was only found in simulations with config-MC. However, a high risk of skull, lower extremity, brain, and neck injuries were more pronounced for cases with config-CM. A high risk of DAI was also noticed for the child. In simulations with config-CM the child exhibited a higher risk of severe injury.
ARTICLE HISTORY
The objective of this work is to develop a finite element model of active human skeletal muscle, which can mimic its contraction behaviour. The model is then used to analyse the effects of active muscle contraction into occupant kinematics and injuries during rear-end collision.
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