Creep Relaxation of a Beam of General Cross Section Subjected to Mechanical and Thermal Loads

Abstract

Creep relaxation of a beam of general cross-sectional area subjected to mechanical and thermal load is obtained. Temperature is assumed to be a function of Z, the height of the beam, and the mechanical moment on the cross section M. The stress in the beam is obtained as a function of time. It is concluded that the point of zero stress shifts, and therefore, the neutral axis of the beam moves toward the lower stress magnitude portion of the cross section, and as time passes it sharply drops to a large stress of the opposite sign that for a large enough time will exceed the allowable stress, and therefore causes failure of the beam.