Helical springs, particularly those used in automotive suspension systems, are designed to offer high strength, uniform stress distribution, and excellent fatigue resistance. These characteristics are crucial for ensuring the safety and performance of vehicles. The design and failure analysis of helical suspension springs, such as the SAE-9254 helical suspension spring, highlight the importance of these properties.
The SAE-9254 helical suspension spring is noted for its high fatigue, sag resistance, high strength, and toughness with a fine grain structure. These attributes make it an ideal choice for automotive suspension systems, where it can withstand the stresses of daily use without failure. However, the failure of such springs can lead to severe accidents, economic loss, and time wastage.The main causes of premature failure in helical suspension springs include raw material defects, surface wear, non-metallic inclusions, improper heat treatment, and decarburization.
A study on a failed helical suspension spring during the manufacturing process revealed that the spring failed due to the formation of transverse cracks in its cross-section. Additionally, martensite and bainite were formed due to variations in surface and core hardness. Decarburization and skin hardness on the outer periphery of the spring coil also contributed to its catastrophic failure.
In summary, the design of helical springs, especially those used in automotive suspension systems, requires careful consideration of material properties, manufacturing processes, and stress distribution to ensure high strength, uniform stress distribution, and excellent fatigue resistance. Failure modes, such as transverse cracks and variations in hardness, highlight the need for continuous research and development to improve the reliability and performance of these critical components.