Laminate tailoring

One of the key elements in laminated composite structures design is the ability to tailor a laminate to suit the job at hand. Tailoring consists of the following steps. We want to design the constituents of the laminate, and those constituents include the basic building blocks of the individual laminae and as well how they are oriented within the laminate. We design those constituents to just barely meet (with an appropriate factor of safety) the specific requirements for, say, strength and stiffness. 

The analytical tools to accomplish laminate design are at least twofold. First, the invariant laminate stiffness concepts developed by Tsai and Pagano [7-16 and 7-17] used to vary laminate stiffnesses. Second, structural optimization techniques as described by Schmit [7-12] can be used to provide a decision-making process for variation of iami-nate design parameters. This duo of techniques is particularly well suited to composite structures design because the simultaneous possibility and necessity to tailor the material to meet structural requirements exists to a degree not seen in isotropic materials. 

For laminate optimization, which we examined in Section 7.7, we have some strong temptations. We could include many design variables. We could talk about which fibers we would deal with out of a collection of those offered by various manufacturers. In addition, we could consider which matrix materials, what percentage of fibers and matrix that we deal with, what orientation of each of the fiber directions, and the thicknesses of the various laminae. All of those various factors are potential design variables, and, in order to treat them, you must have a fairly complicated optimization scheme to be able to achieve the objective of actually tailoring a laminate for specific design requirements. 

The pore size of the membrane could also be controlled independently of the porosity by altering the size of the salt particles (Fig. 5a). Membranes with high surface area/volume ratios were produced and the ratio was dependent on both salt weight fraction and particle size (Fig. 5b). In addition, the crystallinity of PLLA membranes can be tailored to that desired for each application. These characteristics are all desirable properties of a scaffold for organ regeneration. The major disadvantage of this technique is that it can only be used to produce thin wafers or membranes (up to 2 mm in thickness). A three-dimensional scaffold cannot be directly constructed. This problem may be circumvented however, by membrane lamination. 

There are two main types of flexible foam slabstock polyester-based foams, used for technical and high elongation grade laminates or textiles and polyether-based foams used for upholstery, HR, and flame retardance. By varying the type of polyester or polyether, the length of the polyol chain, the structure and size of the hard segment, and the amount of blowing, the foam can be tailored to meet the required specifications. ... 

As mentioned previously, neat pMDI does not have gap filling capability for wood bonding because of its low viscosity and propensity for deep penetration. Consequently, neat pMDI is not used for applications such as plywood, laminated veneer lumber, etc. However, gap filling properties may be achieved by modifying pMDI with a wide variety of difunctional or polyfunctional polyols. Viscosity and NCO content are easily tailored to meet many application requirements. 

Weaver P. Anisotropic elastic tailoring in laminated composite plates and shells. Falzon BG, Aliabadi MH, editors. Buckling and postbuckling structures. London (UK) Imperial College Press 2008177—224. 

In addition, there is also the possibility of tailoring the properties of plain composites further by adding particles (such as metallic fillers [29,30], carbon nanotubes [31] or urea formaldehyde [32]) to the composite layers to create multifunctional and self-healing materials, von Klemperer and Maharaj [29] added copper and aluminium powder fillers to carbon fibre epoxy laminates to improve the electromagnetic shielding capacity of the composite panels. Blast tests on the laminates [30] showed that the laminates with filler particles outperformed their plain composite counterparts, although the margin was small. 

In the area of interior architecture the properties of available fabrics and the diversity of their application are expanding rapidly. For example, products such as ETTLIN lux (ETTLIN, 2009) create fascinating optical effects when back-Ut, as a result of its tailor-made weave properties flexible, temperature-sensitive, colour-changing films such as ChroMyx by Chameleon International (2009) can be laminated onto a variety of fabrics for yet unforeseen purposes. 

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