Key Engineering Materials Vol. 830

Abstract: This study uses the dies of the dray fasteners processing graphics provided by the fastener’s industry to establish 3D dies and components solid models based on the embedded drawing function tools provided by the component model (Standard.ipt) of Autodesk Inventor CAD software. After finishing the dies and components drawing, the integrated assembly drawing of dies can be obtained through the assembly model (Standard.iam) firstly. Three stages forming processes can be conducted and carried out the FEM simulation to check the forming acceptance. The effective stress, the effective strain, the velocity field, and the forging force can be obtained by the FEM simulation. Moreover, the realistic experiment can be performed to verify the acceptance of FEM simulation. The dimensions of final product can be measured to get the errors between FEM and experiment. It is noted that the errors show a good agreement with the experiment.

Abstract: Finite element method is used in this study for analyzing the process of chrome molybdenum tapping screws and discussing the effect of different process parameters on the formability of tapping screws. In the research process, SolidWorks matched with 3D scanning is first used for drawing the physical mold, which is then imported to DEFORM, a finite element forming software, for the tapping screws forming simulation and analysis. Through the spring constant adjustment of three different sliding upper dies, the simulation results and the physical measurement size are compared the difference in diameter or length before and after the formation, which does not exceed 2.38% at most. The research result could assist manufacturers in establishing the forming analysis process of tapping screws to find out the optimal mold and process parameters. In addition to prevent tail screws from defects in the production process, it could be used for the development and process evaluation of new-style screws.

Abstract: The main objective of this research was to investigate the effect of friction on the behaviour of the metal flow and ring geometry, using comparisons from a stationary and rotating bottom die. This was carried out using friction calibration curves, compressive force analysis, stress and strain relationships and the reduction ratio of the ring specimen. The ring compression test (RCT) is considered one of the most reliable ways to obtain the friction factor existing in a plastic deformation process. This technique utilizes the dimensional changes of a test specimen to determine the magnitude of the friction factor. The variation of the calibration curve for the stationary die, with a range of m=0.0 to 0.9, and for the rotating die a range of m=0.1, 0.5 and 0.9. The frictional factor is calculated using FEM analysis, friction calibration and reduction ratio curves were generated from the compressive force using the DEFORM software package. The results indicated that the change in the inner diameter is related to the friction conditions and angular velocities at the die-workpiece interface.

Abstract: Stretch-flanging commonly appears at the concave edge of the panel part. Sheet thickness tends to decrease at the center of flange attributed to the outflow of metal flow, and hence causes a radial shrinking of the material. This shrinking pulls the ends of the flange and makes the adjacent surface overcrown. In this paper the effect of punch profiles on a laboratory scale profile, which assimilates the front fender part adjoining the head light, was investigated for the stretch-flanging process. Both the concave and convex punch profiles were considered. SUS 304 stainless steel sheet of 0.6 mm thick was used as the model metal sheet. DynaForm software was used in simulating the stretch flanging process and followed by experimental verification. The results show that a depression angle of 4.4° and an elevation angle 2.6° can produce lowest crown-contour for the concave and convex punches, respectively. The concave punch also causes less thinning at the flange center which makes it a favorable solution than that of the convex punch.

Abstract: The microwave dielectric properties and microstructures of the (1-x)(Mg_0.95Zn_0.05)₂TiO₄-x (Ca_0.8Sr_0.2)TiO₃ ceramics prepared using the conventional solid-state route were investigated. The structure and microstructure were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Ilmenite-structured (Mg_0.95Zn_0.05)TiO₃ was detected as a second phase. The coexistence of the second phase, however, did not degrade the dielectric properties of the specimen because the phases were compatible. At x = 0.07, a dielectric constant (ε_r) of ~17.86, a quality factor (Q×f) value of ~ Q×f~133,600 Hz (at 10 GHz), and a temperature coefficient of resonant frequency (τ_f) of ~ –5ppm/°Cwere obtained for 0.93(Mg_0.95Zn_0.05)₂TiO₄-0.07(Ca_0.8Sr_0.2)TiO₃ ceramic sintered at 1240°C for 4 hr. The dielectric is proposed as a candidate material for low-loss microwave and millimeter wave applications.

Abstract: High-strength steel is widely applied due to its excellent mechanical properties. However, its high strength in turn brings great difficulties to production and processing such as hot strip rolling owing to the high rolling force, which results in large elastic deformation of roll stack and poses a huge challenge to the control of strip crown and flatness. In this paper, A three-dimensional (3D) elastic-plastic coupled thermo-mechanical finite element (FE) model for hot strip rolling of high-strength steel is developed and then verified experimentally. This model not only calculates the elastic deformation of rolls and plastic deformation of strip simultaneously, but also considers the effect of temperature variation during hot strip rolling. Based on this valid model, the effects of bending force and shifting value of work roll (WR), back-up roll (BR) size, entrance strip crown and rolling force on strip crown have been investigated quantitatively. The results obtained provide valuable guidelines for industrial strip production.

Abstract: The purpose of this paper focuses on adhesive layer strength while having a thermal cycling of honeycomb composite sandwich structure by using the uniform design of experiments method improving the von Mises stress of honeycomb structure. Three system parameters of the honeycomb structure are selected as the control factors to be improved. Uniform design of experiment is applied to create a set of simulation experiments. Applying ANSYS/Workbench software, the finite element modelling is investigated and the von Mises stress of the honeycomb structure is calculated under metal-honeycomb core flatwise tensile test. From the numerical results, the best honeycomb structure dimension of all the experiments which causes the smaller von Mises stress is selected as the improved version of design. Finally, the best model of the experiments which causes the minimum equivalent stress is regarded as the improved version of design. Compared with the original design, the result of ASTM C297 improved version is 17.386 MPa, which mean improved 36.28%, ASTM C364 improved version is 19.015 MPa, which mean improved 25.26%, ASTM C365 improved version is 16.86 MPa, which mean improved 12.35%.

Abstract: This study is designed to investigate the influence of multi-beam matrix laser cutting process on NAND Flash package quality, and find out the important process parameters of multi-beam matrix laser process are defocus amount, laser power, cutting speed and material thickness. Then use the finite element analysis software ANSYS to obtain the minimum temperature influence, stress and strain, and use Taquchi method and variance analysis (ANOVA) to find the optimal temperature combination, the optimal combination of stress and strain and its contribution degree. Finally, the reliability is tested by verification experiments, and the error is found to be within 3.638%. It is confirmed that the optimized parameter combination has high repetitiveness. It is hoped that this study can contribute to the multi-beam matrix laser cutting process.

Abstract: Compared with forging and extrusion processes, tube end forming includes various forming methods, such as pipe expansion, bending, bulging, folding, shrinking and profile processing. Therefore, research and development of pipe processing and forming are of great importance in the industry. In this study, the authors used the finite element analysis software DEFORM to analyze the end deformation behavior of the single pass forming. The deformation behavior of the pipe end, load curve and formability are discussed. The single-pass forming die design enables the pipe ends to be formed into two different shapes. By reducing the processing procedures with the geometric design of the dies, the processing advantages of single pass forming are achieved.