3-16 



DESIGN DETAILS 



D1 PECT ION OF LOAD 



SI DE Dl 5TANCE 



Fig. 3-44. Edge and Side 

 Distances and Spacing for 

 Bolt Type Fasteners 



The required distances, in terms of the bolt diameter, are given in Table 3-1. 

 TABLE 3-1 - MINIMUM EDGE AND SIDE DISTANCES AND BOLT SPACING 



If the above distances are used, failure of the connection will occur by local laminate 

 crushing under the bolt or shearing of the bolt (1). 



Table 3-2 gives crushing strengths in way of bolts as a function of ultimate tensile 

 strength of the laminate for woven roving, cloth and mat reinforcement. To determine the 

 maximum bearing stress at the bolt which the laminate will withstand without permanent 

 deformation, or without complete breakdown, multiply the ultimate tensile strength of the 

 laminate by the number given in the "No Permanent Deformation" or "Maximum Load" 

 column respectively in Table 3-2. If several types of reinforcement are used in the 

 laminate, the bearing stress value should be determined by appropriate tests. In the 

 absence of specific test information, the bearing stress value may be determined for each 

 type of reinforcement, and the lowest of these values applied to the whole laminate. This 

 method of calculation will give conservative values. The values given have been extracted 

 from test data for laminates 1/4 inch thick with 1/4 inch bolts. Thinner laminates especial- 

 ly in ranges below 1/8 inch, or larger bolt diameter to thickness ratios, will tend to reduce 

 these values. The use of a bolt diameter to thickness ratio of 2 reduces these values by 

 about 65 per cent for the proportional limit and 70 per cent for the maximum load. The 

 information given here is based on test results reported in References (2) and (3). 



TABLE 3-2 - LAMINATE BEARING STRENGTH 



Bolt bearing stress divided by laminate ultimate tensile strength. 



