Applied Mechanics and Materials Vol. 751

Abstract: According to the coordination and complementation of electric vehicles (EVs) and renewable resources, such as photovoltaic (PV) power generation, a micro gird system including EVs charging station and PV power generation was constructed firstly. Based on the target of maximizing the utilization ratio of PV power, considering the total cost of EVs charging, the time-of-use (TOU) price was introduced to establish the dual-objective optimization scheduling model of EVs charging. Furthermore, NSGA-II multi-objective optimization algorithm was applied to solve the model and the Pareto front of the non-dominated solutions was obtained. Finally, the optimized scheduling control strategy for EVs charging was proposed through normalized sorting of the non-dominated solutions. The optimal scheduling strategy could increase the utilization ratio of PV power on the basis of reducing the cost of EVs charging, promoting the local consumption of PV power.

Abstract: Considering the effect of stress wave, the dynamic buckling of circular cylindrical shells under an axial step load is discussed using the classical shell theories and the state-space technique in the paper. Based on the Hamilton’s principle, the dynamic buckling governing equations of shells are derived and solved with the Rayleigh-Ritz method. If the linear homogeneous equations have a non-trivial solution, the determinant of the coefficient matrix must be equal to zero, so the expression of the critical load on the dynamic buckling is got. The relationship between the critical load and length is obtained by using MATLAB software. The influences of boundary conditions, thickness, the number of circumferential waves and the number of axial waves on the dynamic buckling loads are discussed based on numerical computation.

Abstract: Taking into account the effects of stress wave and the moment of inertia, the governing equations of composite laminated plate under the axial step load are derived by using Hamilton principle. Based on Variable Separation Method, the analytical expression of the critical dynamic buckling load for symmetry composite laminated plates with one edge fixed and three edges simply-supported can be deduced by considering the characteristics of the buckling solution, and the buckling mode is also acquired. Using MATLAB software, the relationship between the critical load and length can be obtained. The influences of different layer parameters and the order of the mode on the dynamic buckling are discussed.

Abstract: Taking stress wave propagation into account, the governing equations of composite bar with the clamped-fixed boundary conditions considering FSDT (first order shear deformation theory) are derived on the basis of Reddy’ theory and solved by the variable-separated method. The analytic expression of the critical buckling load is obtained basing on the characteristics of homogeneous linear equations having nonzero-solution. The results of the theoretical study and the numerical calculation indicate that FSDT has influence on dynamic buckling of composite bar, and the critical buckling load is small when FSDT is considered. They also show that the magnitude of effect taken by FSDT is small when the layer angle is big.

Abstract: Considering the friction and discussing equilibrium of an Elastic Rod constrained to a Cylinder based on the Kirchhoff theory [1].Firstly take Euler angles as variables which describe the attitude of the cross section, establish a simple and clearly physical meanings mathematics model and balance equations, then considering smooth and nonsmooth contact, discuss the balance of an elastic rod constrained to a cylinder under special condition, give its analytical integration [2] and numerical integration, drawing and analysis the influence of force to the shape of an elastic rod constrained to a cylinder.

Abstract: The test was simulated for the thin-walled cylinder structure of aeroengine stator casing. Based on the software of LMS-TEST, the experiment of the structure with bolted flange joints was successfully completed for the vibration test analysis and the paper completed the testing under different pre-tightening force. Through the analysis of the measured data, the corresponding spectrum and difference value curve were obtained, the research results showed that the nonlinear characteristics of the bolted flange joint was significant influence on the dynamic responses of the structure, the various nonlinear vibration phenomenon and the signal asymmetry were obvious under different pre-tightening force, which was closely related to the state of the bolted pre-tightening force. By the information of the spectrum and acceleration difference curve, the extent of the bolt tightness can be determined, which can provide relevant reference information for the diagnosis of bolted joint status in the aeroengine stator casing.

Abstract: This paper presents some experimental results of a bullet impact on composite armor together with numerical modeling approaches. The development of light composite sandwiches for ballistic protection is the target of a project in terms of which the research is being conducted. Traditionally, a vehicle ballistic protection is mainly achieved through metal-based armor which is extremely heavy, hence the increasing popularity of composite sandwiches. Numerical simulations allow for a reduction of the number of experiments needed to obtain appropriate design of ballistic protection, but they require verified modeling approaches and proper material data. Therefore, different modelling approaches for both parts of the composite sandwich have been tested and possibilities to adjust these models to experimental data were investigated.

Abstract: A design of overpressure protection system is presented for the mobile field medical shelters. The system compositions, structures and installations were comprehensively designed and manufactured by the modular analysis method according to the characteristics of defensive logistic operations for chemical, biological, radiological and nuclear air contaminations to the mobile field hospital. The effects of overpressure protection system were verified through a series of experiments on different shelters, which showed that more than 300 pascals overpressure could be achieved in the separate expanded shelters, and more than 100 pascals overpressure could be achieved in the interconnected expanded shelters. The experiments indicate that the overpressure protection system can meet the demands of relevant protection standards, and can provide effective protection for the medical shelters under suddenly CBRN contamination attacks.

Abstract: A finite element simulation study was performed to gain the theoretical head impact velocity about the crash test details. Accuracy of the simulation was verified using qualitative and quantitative comparisons. Based on in-depth examination of crash simulation recordings, energy distributions occurred in the barrier against the car are determined. In this paper, the existing finite element crash analysis of barriers using the LS-DYNA program is further extended to study the dynamic response of the barrier with module structures connected by anchor bolt inserted through concrete bridge decks. The numerical results for various parameters are verified by comparing different models with or without the high strength steel such as HS800.

Abstract: The use of various types of software for rapid identification of potential problems in manufacturing processes is becoming ever more popular. One of such programs is DEFORM, simulation software for forming and heat treatment processes. The purpose of this study was to construct a 3D model of a specific casting, to identify its critical locations and then select the optimum heat treatment procedure preventing cracking. Results of this work include a detailed analysis of stress and temperature fields in the cast part.