Study on the Pin-load Distribution of Multiple-bolted Composite to Metal Joints

The experiment and finite element analysis were made to determine the pin-load distribution of multiple countersunk bolted single-lap joints. In the experiment, the pin-load fractions were evaluated indirectly by the lap-sheet surface strains collected from a few rows of strain gages. The joint strains and pin-load distribution were also obtained directly in the finite element analysis. The calculated strains correlated well with the experiment. Nevertheless, the pin-load fraction results of the both techniques are quite different. The further analysis revealed that the procedure of transforming the measured strains into pin loads is not reliable, since the intrinsic additional bending had not been taken into account. Therefore the appropriate way to determine the pin-load distribution should be the numerical analysis validated by the strain measurement. The another attempt showed that the pin-load distribution can be evaluated by the finite element modeling of two-dimensional shells and beams as well with satisfied accuracy.