This paper aims to present the analysis of the stress level of the parabolic leaf springs under different loading conditions by computer-aided engineering. The failure modes of the leaf springs normally occur under harsh braking or suspension rolling while striking a pothole. The braking condition of the bus is associated selleck chemical Seliciclib with the leaf spring wind-up, whereas pothole striking is related to the suspension roll. To promote bus safety under such conditions, newly designed parabolic leaf springs are evaluated in simulations for their performance. The new leaf spring designs are expected to provide enhanced roll resistance, improved load-carrying capability, and reduced occurrence of potential failure.2. FE Explicit ModelThe standard simulation setup for any commercial FEA software is shown in Figure 1.
As seen in Figure 1, the simulation can be divided into three categories: preprocessing, solving, and postprocessing. First, computer-aided design models are generated for FE meshing. In this study, a manual hexahedra element mesh is applied for the stress analysis of the parabolic springs. To obtain good simulation results, the quality of the mesh is optimized by the element quality index. The materials and properties of the leaf springs and silencers have also been assigned, and these details are shown in Table 1. Boundary conditions to simulate the degree of freedom of the leaf springs under varying loading conditions differ. Figure 1Typical FEA procedures by commercial software.Table 1Materials and properties of leaf springs and silencers.
FE procedures need to be well developed to perform a complex FE nonlinear analysis. Selection of the appropriate solving method is significant. A conditionally stable explicit integration scheme derived from the Newmark scheme from the RADIOSS solver has been introduced (RADIOSS is a copyright of Altair Hyperworks, Altair Engineering Inc.). In dynamic analysis, the equation of motion for discrete structural models is expressed as follows:Mu��+Cu�B+ku=F,(1)where M, C, and K represent the mass, viscous damping, and stiffness matrices. u��, u�B, and u denote the displacement, velocity, and acceleration vectors, respectively. F is the external force vector. In the general Newmark method, the state vector is computed as follows:ut+1=ut+��tut+u�Bt+(12?��)��t2u��t+�¦�t2u��t+1,u�Bt+1=u�Bt+��t[(1?��)u��+��?u��t+1],(2)where �� and �� are the specified coefficients that govern the stability, accuracy, and numerical dissipation of the integration method [16].
A conditionally stable explicit integration GSK-3 scheme can be derived from the Newmark scheme given the following:u�Bt+1=u�Bt+12��t2(u��t+u��t+1),ut+1=ut+��tut+12��t2u��t.(3)The explicit central difference integration scheme can be derived from the relationships. The central difference scheme is used when explicit analysis is selected.