3 



Design Details 



The use of good details in fiberglass construction is of vital importance in producing a 

 successful design. It is the purpose of this Chapter to indicate recommended methods of 

 construction, and to provide guidance for avoiding trouble causing details. Because of the 

 variety of details possible, the number covered has been held to a minimum and the details 

 chosen illustrate principles which are applicable regardless of the exact means by which 

 they are applied. This approach should guide the designer in solving particular problems 

 and developing successful details, even though the exact situation is not covered here. 



APPLICATION OF LOADS 



In any structural design work an understanding of the basic properties of the material 

 used is essential. The basic property of fiberglass laminates which must be clearly 

 understood is the difference between its tensile strength perpendicular to the plies of the 

 laminate and its tensile strength parallel to these plies. The tensile strength perpendicu- 

 lar to the plies is very much less than that parallel to the plies. For this reason there are 

 right and wrong directions of loading, which are illustrated in Fig. 3-1. The variation in 

 strength with direction of reinforcement, which is characteristic of cloth and woven roving 

 reinforced laminates and which is discussed in Chapter 6, has nothing whatever to do with 

 the "wrong" loading direction mentioned here. Those directions are all "right" directions 

 since the loading is parallel to the laminate. 



The reason for this right and wrong direction is simple. As explained in Chapter 5, 

 the properties of fiberglass reinforced laminates are due to the two basic components, 

 fiberglass and resin. Of these, the fiberglass provides the strength and the plastic or 



DIRECTION OF LOAD 



■*- Dl RECT 1 ON 

 OF LOAD 



PLIES OF REINFORCEMENT 



I III I III' 1 '"" 



RE I NFORCEMENT 



a. R| GHT - LOAD PARALLEL TO PLIES 



01 RECT I ON OF LOAD 

 b. WRONG - LOAD PERPENDICULAR TO PLIES 



Fig. 3-1. Right and Wrong Directions of Loading with 

 Respect to Laminate Reinforcement 



3-1 



