Joint design rigid plastics

In the case of rigid plastics, the greatest problems are in reinforced plastics, which are often anisotropic, having directional strength properties. Joints made from such substrates should be designed to stress both the adhesive and the adherend in the direction of greatest strength. Laminates should be stressed parallel to the laminations to prevent delamination of the substrate. ... 

EN 1448 Glass-reinforced thermosetting plastics (GRP) components - test methods to prove the design of rigid locked socket-and-spigot joints with elastomeric seals. 

While a rigid metal component may accommodate these stresses easily, a more flexible plastic part of the same cross section may require extra stiffening in the form of ribs, inserts, or bosses. Much of the design simplicity of molded parts can be lost in making provision for mechanical assembly. By contrast, a bonded joint requires no extra design provision other than a check to ensure that enough joint area is available and that the adhesive meets service requirements. 

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