Wings Under Repeated Thermal Stress

Abstract

When an aircraft changes its speed or altitude, large thermal strains may be set up in the wing structure; sometimes these are of sufficient magnitude for the accompanying stresses to exceed the clastic limit of the material. During its life the aircraft may suffer a large number of cycles of thermal stress. Under repeated thermal loading it is found that four types of stress‐strain system may be set up: permanent elasticity and shakedown to an clastic state, which are safe, and alternate plasticity and incremental collapse, which are dangerous. The present paper investigates these stress‐strain systems and determines the conditions for their occurrence.