Comparing Fatigue Life Reliability of a Composite Leaf Spring With a Steel Leaf Spring

In the present study, the fatigue behavior of an optimized composite leaf spring and a four leaf steel spring have been analyzed and compared. In a paper, issued by co-author, a four leaf steel spring was replaced by a composite leaf spring. The geometry of composite spring has been optimized to obtain the minimum weight under stress and displacement constraints due to the given static external forces. In this study, both above-mentioned leaf springs have been fatigue analyzed. The vehicle movement has been simulated on four different standard roads in ADAMS software and the spring supports reactions have been derived. Stress time spectrum micro-blocks in critical element of leaf springs have been obtained using ANSYS software and considering ADAMS results as loading. The stress time spectrum macro-blocks for long time from the stress time spectrum in micro-blocks have been created according to statistical and random vibration principles. After finding stress probability density functions for composite leaf spring and equivalent steel leaf spring, fatigue reliabilities have been extracted for both of them. Results showed that the fatigue life reliability in composite leaf spring is much better than steel spring.