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Finite element simulations are being more and more applied when studying the crash-worthiness of vehicles during impact. This paper deals with setting up such a simulation and discusses several ways to simplify and verify a simulated crash. For this purpose, a notch impact-testing machine will be released from a certain angle and crash into a model constructed with three different wall thicknesses. The plastic and elastic deformation is measured in the front of the model and is then used for validation of the simulation. In the end, the simulation was found to be in good agreement with the real crash data. [ABSTRACT FROM AUTHOR]

The development of precision machine tools requires an accurate understanding of the thermal behaviour of the tools. Therefore, by developing highly accurate machine tool thermal behaviour simulations, it can accurately forecast the functional performance of a machine tool at the prototype design stage and provide guidance on its design and performance optimization. To improve the accuracy of the thermal simulation of machine tools, it proposed whole-machine temperature field and thermal deformation modeling and a simulation method for vertical machining centers. Based on the studies of thermal-structure coupling finite-element data flow and its critical conditions, it also proposed design and computational methods for obtaining the heat-source power, when various rotational speeds, the forced convection heat transfer coefficient between a rotating surface and the air, the combined heat transfer coefficient between a stationary surface and the air/environment, and key contact surface thermal resistances were considered. Furthermore, this paper performed finite-element simulation analysis based on the constructed whole-machine thermal model, and the temperature characteristics and heat deformation mechanism/state were obtained. After comparing the simulation and experimental results, it verified the effectiveness of the finite-element simulation model and the relevant methods and confirmed that the simulation accuracy for both the temperature characteristics and the thermal deformation had been improved significantly, with a simulation error less than 10 %. [ABSTRACT FROM AUTHOR]

As a widely used engineering material, optical glass is very difficult to process because of its high hardness and brittleness. The material removal mechanism still needs further investigation. In this paper, a mesh-free simulation method—smooth particle hydrodynamics (SPH)—is introduced and an ultra-precision cutting model for K9 glass is provided. Compared with conventional finite element method, the SPH method can effectively avoid mesh distortion when dealing with large deformation problems such as cutting. Several numerical simulations were carried out to further investigate the critical value of transition. Simulation results indicate that when cutting depth is small enough, the K9 glass can be machined in ductile mode and a relatively smooth machined surface without crack can be obtained. The chip is always in irregular and discontinuous way no matter what the cutting mode is. Three cutting tools with different rake angle were used in simulation and the effect of rake angle is analyzed. [ABSTRACT FROM AUTHOR]

In this paper, temperature results obtained by numerical simulations based on three different methods of defining the heat flux load distribution are compared to directly measured temperatures acquired using infrared camera measurement techniques. The heat flux calculations are based on recorded instantaneous grinding power, average grinding power, and power calculated by multiplying the measured tangential forces and the cutting velocity (referred to as calculated power). The results show that the method applied to characterize the input flux load in the numerical model has a significant effect on the estimated grinding temperatures and that the calculated power data produce the best temperature results. [ABSTRACT FROM AUTHOR]

The existing numerical simulations of hydrodynamic characteristics of abrasive waterjet in a cutting head were mainly based on Eulerian grid or arbitrary Lagrange-Eulerian grid method to establish computational fluid dynamics models. However, using these two methods, the abrasive and water were premixed and given an identical initial velocity, which were different from the mixing and acceleration processes of abrasive in the cutting head. This paper presents a more suitable numerical model that the abrasive particle enters into the mixing chamber in a low velocity and is accelerated in the focus tube by a high-speed waterjet from the orifice. In order to model this mixing-and-acceleration process of abrasive and high-speed waterjet, the smooth particle hydrodynamics (SPH) coupled finite element method (FEM) is adopted, in which SPH particles are used to model the high-speed waterjet to adapt its extremely large deformation and FEM is applied to model the discrete abrasive particle, cutting head, and workpiece. As a result, evolution of abrasive and waterjet velocities along focus tube is analyzed; trajectory of single abrasive particle in focus tube is sighted; the relationships between abrasive particle velocities and different water pressures are described; the rule of outlet velocities of abrasive particle vs. dimensionless ratio of diameter is conducted; depth of penetration caused by single abrasive particle impact is obtained. The current model is validated by the existing theoretical and experimental data. [ABSTRACT FROM AUTHOR]