Orthotropic composite

Buczck, M.B. and Herakovich, C.T. (1985). A normal stress criterion for crack extension direction in orthotropic composite materials. J. Composite Mater. 19, 544-553. 

Tirosh J. (1973). The effect of plasticity and crack blunting on the stress distribution in orthotropic composite materials. ASME Trans. J. Appl. Mech. 40, 785-790. 

Other results from this simple analytical approach for orthotropic composites are... 

P(l) The data in Figure 4.13 are indicative of changes to elastic modulus for three basic composite forms unidirectional composites loaded along the fibres (in tension) and in shear and in-plane random mat and orthotropic composites (e.g. woven laminates). 

As a general rule, the thermal conductivity of a composite material is a complex function of the thermal conductivity of the matrix kj and that of the reinforcement (k). In the particular case of an orthotropic composite material, the thermal conductivity of each component (i.e., matrix, reinforcement) is a tensor quantity [k..] with only three components fcjp k and fcjj along major axes, that is, one in the axial direction (fcjj) and two in the transversal directions k and k ). In the particular case of transversely isotropic materials such as fiber reinforced composites, the axial thermal conductivity of the material, expressed in... 

Composite Fabrication. Orthotropic composites were fabricated using the PP/VB (50/50 wt.%) woven preforms. Four fabric preform layers were placed between layers of polypropylene sheet as shown in Figure 2. In order to produce orthotropic composites, the fabric layers were alternately oriented 90° because the woven preforms possessed different fiber counts in the warp and weft directions. The composites were consolidated at 200°C and 3500 kPa using a model 2696 Carver Laboratory Press with heated plates. The thickness of the PP sheets used in the composite fabrication process was varied in order to achieve the desired final composite composition and to control the distribution of the four fabric layers across the composite cross section. 

Figure 2 Layer stacking sequence used during orthotropic composite fabrication.

Several layers of orthotropic composites, e.g. reinforced with parallel systems of fibres, are stacked together in such a way that adjacent laminae are oriented in different directions and thus the strength and stiffness of the composite plate may be tailored to the specific design requirements (Figure 2.9c). 

To overcome the limitations in the Lame theory when applying to orthotropic composite repair systems, a new modified version of Lame s equations (MVLE) was developed by the authors to undertake the analysis of infinitely long orthotropic cyhnders subjected to internal and/or external pressure. The hoop and radial stresses at any point in the wall cross section of an orthotropic cylinder at radius r are given by the following equations ... 

Hence, the four measured engineering constants E, E, Glt, and Plt are sufficient to describe the linear elastic macromechanical behavior of a thin orthotropic composite lamina subjected to plane stress. 

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