Kc. Schulz et al., A STATISTICAL APPROACH TO THE ANALYSIS OF ULTIMATE STRENGTHS OF BOLTED JOINTS IN LAMINATED COMPOSITES, Composites science and technology, 56(5), 1996, pp. 505-517
The general linear models (GLM) routine in the statistical software pa
ckage SAS has been utilized to develop a statistical model for the pre
diction of joint failure in single-shear joints in IM7/8551 graphite/e
poxy laminates on the basis of the results of an extensive bolted-join
t strength resting program. Ultimate joint strength values from the ex
perimental study were utilized as input for the development of a stati
stical approach which combines a set of submodels into a general joint
failure Fortran routine. Ultimate joint strength in IM7/8551 graphite
/epoxy laminates is statistically predicted from geometric and materia
l input parameters. Each submodel predicts ultimate joint strength wit
h an R(2) value of approximately 0.95. The general test parameters inc
lude angle of loading, bolt/hole diameter, edge distance, type of fast
ener head, laminate lay-up and coupon width. The effects of some anoma
lous factors on bolted joint strength were also tested and evaluated;
these factors include the choice of fabric or tape lamina, use of meta
llic hole inserts (bushings and sleeves), nutplated fasteners, oversiz
ed holes and under-torqued joints. The approach is general and could b
e utilized with a laminate joint strength data base to predict joint s
trengths in newly developed material systems with minimal testing. (C)
1996 Published by Elsevier Science Limited