It is well known that slipping in automotive clutches is closely related to the concave deformation of the pressure plate, but the mechanism of this deformation is not clear. A simplified model of a pressure plate assembly is developed by simulating the deformation field of the plate under the condition of continuous sliding, followed by natural cooling to room temperature. The distribution of displacement is obtained from numerical simulations. The equivalent von Mises stresses of the pressure plate with or without concave deformation are analyzed and compared. The mechanism leading to the concave deformation of the pressure plate is put forward in terms of equivalent von Mises stress. The results show that (1) the concave deformation of the pressure plate is produced during the cooling process and (2) the profile of the concave deformation is determined by its thermal stress distribution. The deformation is mainly caused by the overstressed upper part of the inner rim of the pressure plate during clutch operations.

Parallel seam welding (PSW) is the most commonly employed encapsulation technology to ensure hermetic sealing and to safeguard sensitive electronic components. However, the PSW process is complicated by the presence of multiphysical phenomena and nonlinear contact problems, making the analysis of the dynamics of the PSW process highly challenging. This paper proposes a multiphysics simulation model based on direct coupling, enabling the concurrent coupling of the electric field, temperature field, and structural field to facilitate the analysis of the thermal and electrical dynamics within the PSW process. First, this paper conducts an in-depth theoretical analysis of thermal and electrical contact interactions at all contact interfaces within the PSW process, taking into account material properties related to temperature. Second, the acquired data are integrated into a geometric model encompassing electrode wheels and ceramic packaging components, facilitating a strongly coupled multiphysics simulation. Finally, the experimental results show that the simulated weld area deviates by approximately 6.5% from the actual values, and the highest component temperature in the model exhibits an approximate 10.8% difference from the actual values, thus validating the accuracy of the model. This directly coupled multiphysics simulation model provides essentially a powerful tool for analyzing the dynamic processes in the PSW process.

The process design of hot air reflow soldering is one of the key factors affecting the quality of PCBA (Printed Circuit Board Assembly) component products. In order to improve the product quality during the design process, this paper proposes a robust optimization-based finite element simulation analysis method including significant influencing factor screening, robustness evaluation, robust optimization, and reliability verification for the reflow soldering process. The simulation model of the reflow soldering process temperature field based on experiments is constructed and validated. Sensitivity analysis is used to select important influencing factors, such as the last five set temperature zones (T5 to T9) in the reflow oven and the thermal properties of materials such as PCBs (printed circuit boards), BGAs (ball grid arrays), and solder paste, as well as noise factors like the heating environment during the soldering process. Several surrogate models are used to construct the response surface, and the optimal fitting scheme is selected to effectively avoid poor fitting caused by inappropriate surrogate models. The 6σ robust optimization approach is introduced to evaluate and optimize the robustness of the process design parameter where the heating factor is chosen as the optimization target. The reliability analysis method is employed to validate the product quality. This paper establishes a comprehensive robustness analysis method for hot air reflow soldering, effectively reducing design costs and addressing the lack of robustness analysis in the current hot air reflow soldering process design.

Clutch pressure plate temperature prediction is crucial for the structural design and performance evaluation of the clutch. However, due to the complexity of the clutch structure and the non-linear characteristics of temperature changes, accurate temperature prediction of the pressure plate has always been a difficult task, especially when considering cost factors. Aiming at this problem, this paper proposes a pressure plate temperature prediction method based on Bi-directional Long Short-Term Memory (Bi-LSTM) and transfer learning. First, the actual temperature data of the pressure plate under different experimental conditions is collected to establish a Bi-LSTM neural network temperature model, and then, a migration learning method is introduced to migrate the temperature experimental data to obtain a migration model. The migration model is finally applied to predict the pressure plate temperature using three samples and validated by the test. The results show that for the temperature prediction of the same type of pressure plate under different experimental conditions, the MSE (Mean Squared Error) of the approach is 7.08 °C, the R² (R-squared) is 0.90, the maximum error is 8.47 °C, and the maximum relative error is 3.14%. For the temperature prediction of different types of pressure plates, the MSE of the approach is 3.64 °C, the R² is 0.97, the maximum error is 5.94 °C, and the maximum relative error is 1.78%. It shows that the proposed approach achieves high-precision prediction of the clutch pressure plate temperature in the case of small samples, which is difficult to achieve with previous methods. The proposed approach can be used for the temperature prediction of the other clutches of models and working conditions and has broad application prospects.

The quality of solder joints formed by reflow soldering is closely related to the temperature profile of solder joint during the hot air reflow soldering process. The temperature profile of solder joint is directly determined by the process parameters of the reflow furnace as the layout of the PCB design remains same. In this paper, the temperature model of the printed board assembly during reflow soldering is numerically built and simulated to obtain the temperature distribution. Furtherly, several process parameters, such as the temperature of each temperature zone, convective heat transfer coefficient and conveyor belt speed of reflow soldering furnace, are selected as the input variables, and the heating factor, time of super liquidus and peak temperature are aimed as the output parameters. The Latin hypercube sampling design is applied to construct the response surface of the output parameters. The influence of these process parameters during the reflow soldering on the temperature profile of PCBA is studied comprehensively. The main influencing process parameters of the reflow soldering are identified and their influence laws are obtained. The research results provide valuable reference and basis for reflow soldering process design.