Kinetic Modulus of Steel: A New Automotive Design Parameter

Successful automotive weight reduction with high strength-to-weight ratio steels has caused re-evaluation of the basic structural design parameters. This paper introduces the new concept of “Kinetic Modulus” which describes the nature of materials in motion. Kinetic modulus is influenced by stress and strain amplitude, yield strength and the number of loading cycles. The scope of kinetic modulus encompasses: elastic, secant, dynamic and tangent moduli; each of which is a specific case of kinetic modulus at a particular condition. Theoretical and experimental results are presented to support this concept. They show that high strength steel has higher dynamic stiffness and improved vibration response in structures as compared to that of lower strength steel. Thus, high strength steel (“Stiff Steel”) can be used advantageously in stiffness controlled automotive structures to achieve greater weight reductions.