Viscoelastic column dynamic creep buckling - failure probabilities and survival times
by
Harry H. Hilton
Univeristy of Illinois at Urbana-Champaign

Dynamic viscoelastic column creep buckling is investigated by including in the analysis inertia terms for the entire time interval as well as time dependent transient loads during the initial load build-up. Computer simulations confirm that column deformation and stability (time to creep buckle) are radically altered due to the inclusion of inertia effects when compared to equivalent quasi- static results for both small and large relaxation time values. It is also demonstrated that viscoelastic materials exhibiting finite long time strains are subject to additional static as well as dynamic creep buckling load constraints which do not apply to materials with unbounded long time creep strains. Alternate creep buckling time hypotheses based on strain reversal, constancy of slopes of deflection logarithms and on deterministic and/or stochastic material time dependent failures are formulated and examined.

Viscoelastic materials exhibit degradations of relaxation moduli and failure stresses with time. Consequently, since deflections increase due to creep and failure stresses decrease, it is only a matter of time before either creep buck-ling or delamination will occur. The concept of column lifetime or survival time based on probabilities of failure is, therefore, formulated and evaluated including temperature effects. The failure criterion is based on combined compressive, bending and shear stresses and considers delamination onset as the failure condition.

Date received: January 15, 2002

Copyright © 2002 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cago-29.