Description and Analysis of Structural Design Improvement of Liftgate Hinge Reinforcement Plate_Hing1

In recent years, the automobile industry in my country has experienced rapid development, particularly with the addition of self-owned brands and joint venture brands. This has led to a reduction in automobile prices and a flood of tens of thousands of cars entering the consumer market annually. As the times progress and people's incomes improve, owning a car has become a common means of transportation in thousands of households, contributing to increased production efficiency and improved quality of life.

However, the frequent occurrence of car recalls due to design problems in the automotive industry serves as a reminder that when developing new products, attention should not only be given to development cycles and costs, but also to product quality and user needs. To ensure better quality and satisfaction for consumers, the "Three Guarantees Act" for automotive products sets stricter requirements, including a minimum validity period of 2 years or 40,000 km, and a minimum validity period of 3 years or 60,000 km. Therefore, it is crucial to focus on the early stages of product development, optimize the design structure, and avoid the need to "make up for" any shortcomings later on.

One specific area of concern in the automotive industry is the occurrence of cracking in the inner panel at the hinge of the liftgate hinge reinforcement plate. This problem was encountered during road tests of actual vehicles, leading to the need to investigate how to reduce the sheet metal stress value in the hinge area. The aim is to optimize the structure of the hinge reinforcement plate and achieve the optimal state to reduce stress values and enhance the performance of the liftgate system. Using computer-aided engineering (CAE) tools for structural optimization can improve the quality of design, shorten the design cycle, and save testing and production costs.

The analysis of the cracking problem in the inner panel at the liftgate hinge revealed that the boundary at the hinge installation surface and the upper boundary of the hinge reinforcement plate were staggered, causing the inner panel to be under a single-layer stress state, which did not provide adequate protection to the inner plate. This resulted in a cut in the upper boundary of the hinge installation surface, leading to increased cracking. Furthermore, stress concentration at the lower end of the hinge mounting surface exceeded the yield strength of the plate, posing a risk of cracking.

To address these issues, various structural optimization schemes were proposed and analyzed through CAE calculations. Four different schemes were designed, and the stress values of the inner plates were calculated and compared. The results showed that all optimization measures were effective in reducing stress values, with scheme 4 achieving the greatest reduction. However, implementing scheme 4 would require significant changes to the manufacturing process, leading to high mold repair costs and a long renovation period. Scheme 2, which achieved a 35% reduction in stress values compared to the original scheme, was deemed the most feasible and cost-effective solution.

To validate the effectiveness of the chosen scheme, manual samples of the modified parts were created, and vehicle manufacturing and reliability road tests were conducted. The results showed that scheme 3 and scheme 4 were successful, while scheme 1 failed. Based on these findings, the optimal improved structural design scheme (Scheme 4) of the hinge reinforcement plate was determined. However, to address issues of process convenience and perceived quality, further improvements were made to the structure of Scheme 4, resulting in a final design that eliminated boundary staggering, improved process operation, and ensured consistent application of sealant.

In conclusion, the analysis, optimization, and validation of the hinge reinforcement plate structure demonstrated that the reduction of stress values in the inner plate at the hinge is closely related to the design of the hinge reinforcement plate. While increasing sheet metal or using special processes can achieve some reduction in stress values, these approaches often complicate the process and increase costs. Therefore, it is crucial to carefully design and optimize the structure of the hinge reinforcement plate from the early stages of product development to achieve the best results in terms of stress reduction. Continuous improvement in product design and manufacturing processes is essential to meet the increasing demands for quality and reliability in the automotive industry.