Applied Mechanics and Materials Vol. 141

Abstract: In the practical engineering, to solve the small failure probabilities with correlated high-dimensional variables, the subset simulation (SS) is combined together with the Monte Carlo and importance sampling (IS) method. The samples from the probability density functions (PDF) of the importance sampling are used to construct the intermediate failure events, by which the small failure probabilities are turned into a Markov chain (MC), which is a continuous product made of a series large failure probability or conditional failure probability (CFP) which is easily answered, on which the structural reliability can be efficiently simulated by directly obtaining the samples with correlated ones. Finally, the 3 planet carriers of 3 grade planetary reducers in shield tunneling machine(STM) are as examples to check the algorithm above, the results show that the SS of the IS with correlated variables can highly simulate failure probability.

Abstract: This paper focuses on the ride comfort of off-road vehicles, which requires rising steadily. The objective methods for determining ride comfort including the Average Absorbed Power, BS 6841, VDI 2057 and ISO 2631 were investigated. Research shows that all the methods can be used to specify and evaluate ride comfort, but the Average Absorbed Power is more suitable for off-road vehicles. The solutions to improve ride comfort of off-road vehicles in suspension and seat were investigated too.

Abstract: According to an electrical vehicle (EV) construction and working principle, a dynamic model governing its motion was established. A built-in permanent magnet synchronous motor was selected as its driving motor and a mathematical model about the motor working principle was described also. To get good motion effect, a motor driving control system with a current loop and a speed loop was developed. The current loop consists of maximum torque per ampere control and field weakening control. The speed loop is based on a sliding mode control. To make the EV working more smooth, stable and safer, its traction control includes driving motor control and wheel braking control. During some acceleration or cornering, wheel braking control is introduced to keep driving wheels in good slip states, especially to make the car in a good stable and safe state. Simulation study based on MATLAB/Simulink showed the control strategy developed here can make the EV work well, even when it runs on some asymmetric road.

Abstract: The conception and realization of scale transformation stochastic resonance (STSR) are proposed, which are used to deal with problem of weak signal detection with large parameters that can not be resolved by traditional bistable system based on stochastic resonance. Magnetic flux leakage (MFL) signals inspection for oil well tubing defects is easily destroyed by noise. In order to detect weak MFL signals effectively, the proposed STSR technology is applied to the inspection. The result shows that the STSR technology has the potential application in engineering practice.

Abstract: Durability is very important to evaluate the performance of electric nail gun. This paper has studied the working principle of the electric nail gun; and presents a method for evaluating parameters of the electric nail gun durable test, and the general procedures for durability test of electric nail gun; and developed the devices of durability test of electric nail gun on special model.