Like all traditional materials of construction, composites also have an inherent limitation - low modulus of elasticity (read: stiffness). However, this drawback has been successfully overcome by structural design engineers over the years through effective use of the principles of geometry! If composites are to be successfully used as load bearing components for building applications, their structural form must be chosen as to overcome the apparent lack of stiffness in the overall structure. The required rigidity of the structure is then derived from its shape rather than from the material-the strength of the structure is, of course, only a function of the structure of the material. With composites, stiffness can be introduced in several ways by a mere change in geometry such as introduction of corrugations or curvature, provision of stiffening ribs or resorting to sandwich construction. The choice and form of reinforcement is crucial in ensuring superior mechanical properties at competitive costs.


ESSJAY’s expertise guides customers in choosing the correct form of reinforcements [whether chopped roving (random orientation), woven roving (bi-directional), combination of chopped roving and woven roving (random + bi-directional), uni-directional mat, multi-axial fabrics (bi-axial, double bias, triaxial and quadaxial), resins and processing technique suitable for the end product and application]. 

The choice of reinforcements at the design stage itself determines economics of production (with respect to fiber/resin ratio and prediction of mechanical properties of the molded end product).

The choice of resin type (orthophthalic/isophthalic/ terephthalic/bisphenol type unsaturated polyesters/ vinyl esters/epoxies/polyurethanes/phenolics/hybrids) is also critical at the design stage itself in establishing failure mechanism of the composite (based on strain-to-failure characteristics of the resin) apart from the long-term behaviour (weathering/UV degradation etc) of the resin when the composite product is in service.


As an example, the use of flexible resins with high elongation at break is advantageous in automotive & rail transport applications where products are subject to cyclic-type loading caused by motion of the vehicle. This involves complete product design (starting from first principles such as fiber loading, % fiber content, deflection criteria, Moment of Inertia), prediction of mechanical properties, prototyping & testing followed by production runs. 

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