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The most common problem is that geometrical variations may depend on lay-up, material, processing temperature, tooling geometry etc., which makes the problem more complex. To solve this problem requires more powerful computational models. Increasing the simulation capacity for the manufacturing processes is an important step towards a more cost efficient development and manufacturing of composite structures.Some attractive examples from industry can be given, where the above mentioned problems occur during manufacturing.The 27 m long A350 XWB rear wing spar forms the structural heart of the aircraft wing’s fixed trailing edge,holding vital parts such as the main landing gear.Aileron ribs and fuselage stringers also can be given as examples in the same context. In aerospace applications, the autoclave manufacturing method is used to manufacture these structures. Similar structures can be manufactured using the pultrusion process if the cross section of the structure is constant. Vertical axis wind turbine blades can be an innovative example [1, 2]. Manufacturing large blades in one step using a single die will lead to cost reduction for large series production. In addition to these manufacturing methods, the resin transfer moulding (RTM) method can also be used for manufacturing of aileron rib.The inboard flaperon of the BA609 (Bell Agusta), which is an aerodynamic control surface also presents different critical features. In fact, the inboard flaperon is a primary component so the reliability must be nearly absolute [3]. Developing computational models requires deep knowledge of the mechanisms generating the geometrical variations. In this context residual stresses developed during manufacturing should be examined. Residual stresses can be categorized according to the scale at which they originate and whether they are thermoelastic or non-thermoelastic.Residual stresses can be grouped as micro scale residual stresses and macro scale residual stresses. Micro scale residual stresses develop between the fibers and resin as a consequence of (i) thermal expansion mismatch between the fibers and resin, (ii) chemical shrinkage of the resin during polymerization, and (iii) moisture absorption. The residual stresses at this scale do not cause any distortions of the composite laminate although they adversely affect the strength of the laminate by matrix cracking.
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