3-2 DESIGN DETAILS 



resin provides the means of holding the fiberglass in place. Loading a laminate in the 

 wrong direction places the load on the resin, and the glass reinforcement cannot act. 

 Therefore, when a load is applied in the wrong direction, as with cleats secured to a deck, 

 mechanical fasteners completely through the laminate should be used. The only exception 

 to this rule may be in the case of very light loads. 



Assuming the loads are applied in the right direction or parallel to the plies, the next 

 consideration is the orientation of the reinforcement to suit the loading. This is particu- 

 larly important with cloth and woven roving reinforcements. The designer should be 

 familiar with the strong and weak directions, and make every attempt to place the laminate 

 reinforcement with the strong or warp direction in line with the direction of the principle 

 stress. This principle applies both to the lay up of the over-all laminate and to local 

 increases in thickness in way of local loading. 



LAMINATE CONNECTIONS 



One of the major advantages of fiberglass construction is that, in many cases, the 

 basic material may be used to form the connection between two parts, in a manner 

 analogous to welding in steel construction. The basic requirement for all joints is that 

 the laminate be loaded in a direction that will not tend to delaminate it; that is, pull it 

 apart. 



In secondary bonded joints, i.e. joints using an adhesive to connect cured laminates, 

 subjected to shear tending to slide one laminate past the other, it is recommended that a 

 layer of resin impregnated fiberglass mat reinforcement be placed between the joining 

 surfaces since it acts as the adhesive carrier and as a reinforcement. Fiberglass mat is 

 preferred since it retains the adhesive and its random distribution of glass fibers provides 

 reinforcement in the joint opposing the shear force. 



Deck to Shell 



One of the most common connections which must be made is the deck to the shell. 

 There are many possible means of making this connection and the final selection of a 

 detail must be based on satisfying a number of requirements. These requirements will 

 sometimes conflict and some compromise must be decided upon. The following basic 

 principles will guide in the design of a good joint: 



A joint should develop maximum efficiency or the full strength of the weaker 

 of the two pieces being joined. This is the most important criterion of a pro- 

 posed design; the one which overrides all other considerations. The exterior 

 reinforcement shown in a number of the following figures will create a condi- 

 tion where good exterior appearance will be difficult to obtain. If, however, 

 sufficient strength cannot be obtained without this exterior reinforcement, the 

 effect on appearance must be accepted or the joint design modified if possible. 



A joint must be easily made by the fabricators. Quality control in fiberglass 

 construction is all important, and a joint that the workman can do well will 

 often be stronger than a joint which appears stronger on paper but cannot be 

 easily made and inspected. 



