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Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes...

This paper introduces several commonly used constitutive models of SMA materials, expounds the relationship between material temperature, stress and strain from the perspective of one-dimensional model, and establishes the simulation model of reciprocating motion of SMA actuator based on the material parameters obtained from quasi-static mechanical property experiments in the previous paper. A double wire pull SMA actuator is designed and a prototype is made. The output displacement data obtained from the experiment is compared with the established simulation model to prove the accuracy of the simulation process.

Aiming at the problems of vibration and noise in automobile design, a study on the use of shape memory alloys (SMA) to suppress the vibration of thin-walled car bodies is proposed. Using SMA to suppress the vibration of the thin-walled structure, an experimental model was designed, and the finite element analysis software was used to perform modal analysis on the thin-walled structure. A number of different SMA layouts were set up, and the layout of the vibration experiment was determined through simulation analysis. form. A vibration experiment test platform was designed and built. Based on the results of modal analysis, multiple sets of thin-walled structure vibration experiments were conducted under different conditions, and the change data of the displacement, velocity and acceleration of the thin-walled structure before and after the use of SMA under external excitation was obtained. . The research results show that the amplitude, speed, and acceleration of the thin-walled plate structure with SMA are reduced by about 50%-70% after the temperature load is applied; the suppression effect is positively correlated with the number of SMA wires used.

Variable thickness hybrid square (VTHS) tubes which had variable thickness of CFRP to achieve the variation of axial crushing performance are proposed. To study the crushing characteristics and relative advantages of the VTHS, pure aluminum tube, uniform hybrid square tube and VTHS were manufactured firstly, and their axial crushing tests were conducted. Experimental results showed that, compared with uniform hybrid square tube, VTHS had lower initial peak crushing force. Finite element models were established and verified to explore the effect of parameters of the tubes on axial crushing performance further. Numerical results showed that the crushing force can be controlled by varying the thickness of CFRP. Compared with uniform thickness hybrid square tube, VTHS had an improvement of 24.5% in specific energy absorption and increase was greater for the VTHS with thinner metal. Effects of the mean thickness, thickness difference, and number of segments of CFRP on the energy absorption performance were studied. Finally, a theoretical model to predict the mean crushing force was proposed and its accuracy was verified by tests. Results demonstrate that theory can be used to obtain the mean crushing force of each segment of VTHS accurately.

This work studies the impact protection properties of both martensite NiTi wires and superelastic NiTi wires, with 0.5 mm diameter, at different initial impact energies using a new-designed impact test plant. In particular, impact experiments under a specific temperature range of A s - A f , were performed for the martensite NiTi wires. The test results show that both the martensite NiTi wires and superelastic NiTi wires have excellent impact protection properties and can dissipate a significant amount impact energy compared to other more metal materials such as Cu, Fe, and Al. Otherwise, the martensite NiTi wires can dissipate more impact energy in a shorter period of time than superelastic NiTi wires while generating a smaller impact force, F max , due to their larger plastic deformation energy. Moreover, the dissipated energy, W d , of martensite wires increases from 23.8 MJ/m3 to 53.6 MJ/m3, and the impact force, F max , increases from 42.96 N to 95.9 N, while the temperature rises from 35 °C to 65 °C. That means the impact protection properties of martensite NiTi wires are temperature dependent in a specific temperature range A s - A f . Those results in this study also reveal that the impact protection properties of both martensite NiTi wires and superelastic NiTi wires represent the basis for new shape memory damping element applications, particularly in automotive safety systems.

A new kind of piezoelectric pump with triple vibrators was presented. The pump adopted circular piezoelectric vibrator with a hole in the middle, and a check valve was adhered to the hole to cut off air. The working principle of the pump was analyzed. A prototype of piezoelectric pump was fabricated and measured. The experimental results show: (1) The maximum flow rate of the piezoelectric pump under the working mode of vibrators 1, and 3 driven synchronously and vibrator 2 driven asynchronously reached to 1513.2 mL/min when driving frequency was 220 Hz, and the maximum pressure reached to 4.08 kPa when that was 140 Hz. (2) The output performance of the piezoelectric pump with triple vibrators was the best under the working mode of vibrators 1, and 3 driven synchronously and vibrator 2 driven asynchronously. (3) When only two vibrators participate in working, the best connection method was vibrator 1 not driven and vibrators 2, and 3 driven asynchronously. (4) When only one vibrator participates in working, the best connection method was vibrator 3 driven solely.

This paper focuses on the crushing collapse theory of externally fiber-reinforced twelve right-angle section (TTRS) tubes based on the kinematic approach. This paper presents the crushing energy dissipation mechanism of metal TTRS tubes and derives the expression of mean crushing force. Considering the contribution of the composite-metal wall and the final crushing deformation, which affected by the accumulation of the composite after failure, the expression describing the mean crushing force for externally fiber-reinforced TTRS tubes is presented. The accuracy of the theoretical predictions is validated by finite element simulations, including four different metal wall thicknesses and three different amounts of composite plies. The results indicate that the mean crushing forces calculated by the proposed theory show a good consistency with the simulation results.

The energy dissipation properties of martensite NiTi SMA wires under two different loads, including a quasi-static tensile load and an impact load, are studied through our newly designed testing plants. Meanwhile, by changing the temperature of the SMA wires, the controllability of energy dissipation of the SMA wires is discussed in detail. The results indicate that martensite NiTi SMA wires show excellent energy dissipation capabilities under the loads. It is also found that the energy dissipation properties of the SMA wires can be improved by changing their temperature. The energy dissipation properties of martensite NiTi SMA wires demonstrate that NiTi SMAs have the possibility to be applied in smart automotive safety systems.

In engineering practice, shape memory alloys need to keep stable basic properties such as memory effect and super elasticity in a different climate environment. In order to get the weather resistance of SMA, this article uses the high/low temperature test chamber to simulate different climate environments. The same parameters and the same batch of the SMA wires are taken as experimental objects. SMA wires static stretching experiments are performed after environmental box test. The experimental research shows, the SMA materials do not loss the basic mechanical properties for the environmental changes. The SMA wire stress changes can be neglected. The more cycles it takes, the larger residual strain it remains. After more than 120 cycles, the residual strain becomes stable and the SMA wires show good weathering ability.

This article introduces the β phase plane method to determine the stability state of the vehicle and then proposes the electronic stability program fuzzy controller to improve the stability of vehicle driving on a low adhesion surface at high speed. According to fuzzy logic rules, errors between the actual and ideal values of the yaw rate and sideslip angle can help one achieve a desired yaw moment and rear wheel steer angle. Using genetic algorithm, optimize the fuzzy controller parameters of the membership function, scale factor, and quantization factor. The simulation results demonstrate that not only the response fluctuation range of the yaw rate and sideslip angle, but also the time taken to reach steady state are smaller than before, while reducing the vehicle oversteer trend and more closer to neutral steering. The optimized fuzzy controller performance has been improved.

The dynamic characteristics of multilayered piezoelectric actuator (MPA) are analyzed by using the Finite element method (FEM) and experimental methods. The results of FEM show that the resonant frequency of expending mode is 38.5 kHz. The result of impedance analysis is 68.75 kHz and the result of sine sweep method is 7 kHz. The Comparative analysis of FEM and experimental results shows: the Resin encapsulation structure which is not considered in finite element model affect the accuracy of the analysis result; the impedance analysis method has a high accuracy for the test of; the power limit of voltage source and the capacitive characteristic of multilayered piezoelectric actuators lead to a fast decrease of displacement amplitude.

The factors which influence the pressure of fluid in the Electro-rheological (ER) valve are analyzed; The kinematic equations of ER Fluid under the electric field are established; The prototype of multi-channel cylindraceous ER valve is manufactured based on the technical requirement of ER valve; The flow characteristics of the fluid in the valve are analyzed by the software of Fluent; The test bench of ER valve is built and the influences of the actuator’s driving ability according to the flow acreage of ER valve are analyzed; The static pressure endurable ability of ER valve and the instantaneous hydraulic pressure endurable ability under the circumstance of high speed flow are studied; The characteristics of hydraulic pressure endurable ability of parallel ER valve are obtained.