Abstract:

To solve the unknown problem of thermally induced vibration (TIV) of slender rod-beam structures without cross-section temperature gradients under temperature loads,the “L-shaped” right-angle beam is taken as the object,and the TIV mathematical model and the equivalent axial force method are proposed.Based on the finite element method,the nodes’ temperature changes of different elements are equivalent to the thermal axial force for loading,with dynamic analyses carried out.It is verified that TIV occurs as long as the temperature changes cause the structure to deform and that the temperature fields change rapidly,even if there are no cross-section temperature gradients.The theory of “only the temperature gradients in the cross-section can cause TIV” is improved,and this paper provides a new method for studying TIV of complex structures.Then in the “L-shaped” right-angle beam study,the results calculated by this method are compared with those by the equivalent displacement method,with the results indicating that their error is within 0.002 2%,but the time required by the equivalent axial force method is 79% less than that by the equivalent displacement method,which verifies the rationality and effectiveness of this method.What is more,the interaction between the rods can cause the structure to bend,which can lead to TIV under a certain temperature condition.Finally,TIV of the hoop-truss is analyzed based on the method in this paper.

Key words: thermally induced vibration, thermal shock, slender rod-beam structures, without cross-section temperature gradients, finite element analysis