The aim of the experiment is to determine, by experimental methods, the imperfections inherent in struts, for up to three materials i.e. steel, brass and aluminium.
The experiment was performed to examine the buckling phenomenon of the struts. After the completion of experiment results were compared with the theoretical results. Three struts (steel, brass and aluminum) of different length were used in this experiment. All the specimens were pin-end joints. Load was applied on the specimen at the specified locations on the specimen. All the pin-end struts of various materials were tested. Finally the critical load measured was compared with the theoretical results i.e. Euler predictions. It was hard to find out the critical load in the aluminum struts since it has a plastic behavior in the deformation. For the given steel struts the experimental results are close to the Euler predictions.
The aim of the experiment is to determine, by experimental methods, the imperfections inherent in struts, for up to three materials i.e. steel, brass and aluminum.
Generally in a truss structure member which undergoes in tension was called as a tension member and member which undergoes compression is called as a strut member. Very short columns will fail at the crushing load, but the compression members like struts are not fail entirely due to crushing. These members are considerably long in comparing with the least lateral dimension. Hence these strut members start bending i.e., buckling withe load reaches a certain critical value. Once a member shows a signs of buckling it will lead to the failure of a member. This load at which the member just buckles is called the buckling load or critical load or crippling load. The buckling load isless than the crushing load. The value of the buckling load is low for long members and relatively high for short members. The value of the buckling load for a given member depends upon the length of the member and the least lateral dimension. When an axially loaded compression member just buckles, it issaid to develop an elastic instability.
Failure of the long columns due to buckling phenomenon was discussed by Euler and his theory on long columns solved so many problems. In his theory he was discussed four cases
case 1 when both ends of the members are pinned.
case 2 when one end is fixed and the other is free.
case 3 when both ends are fixed.
case 4 when one end is fixed and the other is pinned.
Case 1 is considered in the experiment since the both ends of the strut member are pin jointed.
Euler analysis of this type of problems have made following assumptions Strut material should be homogeneous and it should be linearly elastic i.e. it should obeys Hooke’s law. Strut should be perfectly straight and should be no imperfections Loading should be applied on the ends of the strut and it should be applied at the centroid of the cross section at the ends.