How to choose the installation position of the hinge on the side of the body to prevent the hinge fr1

With the development of society and the improvement of people's living standards, cars have become a favored means of transportation for more and more consumers. When buying cars, consumers pay more attention to safety and quality durability, rather than just eye-catching novel shapes. Meeting the needs of users within the useful life of auto parts is the main goal of automotive reliability design. The strength and stiffness of the parts directly affect the service life of the car.

One of the most eye-catching body components of a car is the engine cover. It serves multiple functions, including facilitating maintenance of various parts in the engine compartment, protecting engine components, isolating engine noise, and protecting pedestrians. The hood hinge, as a rotating structure for fixing and opening the hood, plays a vital role in the functionality of the engine cover. The strength and rigidity of the hood hinge are of great significance in ensuring it functions properly.

During a 26,000km vehicle reliability road test, the body side bracket of the engine hood hinge broke, causing the engine hood to be unable to be fixed, thus impairing driving safety. After analyzing the cause of the hinge break, it was found that errors in manufacturing, tooling, and human operation processes can accumulate and cause mismatches in the whole vehicle assembly. This can lead to problems such as abnormal noise and interference during road tests. In this particular case, the fault was due to the hood lock not being properly locked at the second level, resulting in vibrations along the X and Z directions that caused fatigue effects on the body side hinges.

In engineering practice, parts often have holes or slotted structures for functional or structural reasons. However, experiments show that sudden changes in the shape of a part can lead to stress concentration and cracks. In the case of the broken hinge, the fracture occurred at the intersection of the shaft pin mounting surface and the hinge limit corner, where the shape of the part changes suddenly. Additionally, factors such as the strength of the part material and structural design can also contribute to part failure.

The side hinge of the body was made of SAPH400 steel material with a thickness of 2.5mm. The material properties indicated that the joint strength of the material was sufficient to withstand the stress imposed on it. Therefore, it was concluded that the selection of the hinge material was correct. The fracture was mainly caused by stress concentration at the gap.

Further analysis revealed that the installation points and structure of the hinge also played a significant role in its failure. The inclined angle of the hinge installation surface on the body side and the arrangement of the mounting points were found to be critical factors. The oblique triangle formed by the three-point connection between the hinge bolt installation point and the hinge shaft pin resulted in unbalanced support and increased the risk of fracture.

The width and thickness of the hinge shaft pin mounting surface also affected the hinge's functionality and life. Comparisons with similar structures revealed that the maximum dimension from the axis pin hole to the edge of the mounting surface should be limited to 6mm to reduce stress concentration.

The design suggestions based on the analysis included: (1) controlling the angle between the hinge mounting surface on the body side and the X-axis to 15 degrees or less, (2) designing the hinge and shaft pin installation points in an isosceles triangle configuration to optimize force transmission, and (3) avoiding sharp transitions and stress concentration areas by optimizing the shape of the hinge and the end position of the limit mechanism.

In conclusion, the design of the hood hinge is crucial for ensuring customer satisfaction with the functionality of the hood. By optimizing the design and addressing issues related to the shape, force transmission, and installation points, the risk of hinge failure can be minimized, improving the overall reliability and durability of the car.