Deflection of Rectangular Laminated Composite Plates using Dynamic Relaxation Method

كتاب "Deflection of Rectangular Laminated Composite Plates using Dynamic Relaxation Method" ، تأليف : اسامة محمد المرضي سليمان ، نقرأ من الكتاب :

Composites were first considered as structural materials a little more than half a century ago. And from that time to now, they have received increasing attention in all aspects of material science, manufacturing technology, and theoretical analysis.

The term composite could mean almost anything if taken at face value, since all materials are composites of dissimilar subunits if examined at close enough details. But in modern materials engineering, the term usually refers to a matrix material that is reinforced with fibers. For instance, the term "FRP" which refers to Fiber Reinforced Plastic usually indicates a thermosetting polyester matrix containing glass fibers, and this particular composite has the lion's share of today commercial market.

          Many composites used today are at the leading edge of materials technology, with performance and costs appropriate to ultra-demanding applications such as space craft. But heterogeneous materials combining the best aspects of dissimilar constituents have been used by nature for millions of years. Ancient societies, imitating nature, used this approach as well: The book of Exodus speaks of using straw to reinforce mud in brick making, without which the bricks would have almost no strength. Here in Sudan, people from ancient times dated back to Merowe civilization, and up to now used zibala mixed with mud as a strong building material.

          As seen in Table 1.1 below, which is cited by David Roylance [54], the fibers used in modern composites have strengths and stiffnesses far above those of traditional structural materials. The high strengths of the glass fibers are due to processing that avoids the internal or surface flaws which normally weaken glass, and the strength and stiffness of polymeric aramid fiber is a consequence of the nearly perfect alignment of the molecular chains with the fiber axis.