Fibers compressive strength

Kumar S, Anderson DP, Crasto AS, Carbon-fiber compressive strength and its dependence on structure and morphology, J Mater Sci, 28(2), 423-439, 1993. 

The mechanics of materials approach to the micromechanics of material stiffnesses is discussed in Section 3.2. There, simple approximations to the engineering constants E., E2, arid orthotropic material are introduced. In Section 3.3, the elasticity approach to the micromechanics of material stiffnesses is addressed. Bounding techniques, exact solutions, the concept of contiguity, and the Halpin-Tsai approximate equations are all examined. Next, the various approaches to prediction of stiffness are compared in Section 3.4 with experimental data for both particulate composite materials and fiber-reinforced composite materials. Parallel to the study of the micromechanics of material stiffnesses is the micromechanics of material strengths which is introduced in Section 3.5. There, mechanics of materials predictions of tensile and compressive strengths are described. 

Figure 21 Compression strength as dependent on the content of GRP in jute fiber-reinforced hybrid-composites [67J.

In general, the compressive strength of a non-reinforced plastic or a mat-based RP laminate is usually greater than its tensile strength. The compressive strength of a unidirectional fiber-reinforced plastic is usually slightly lower than its tensile strength. Room-temperature compressive stress-strain data obtained per ASTM for several plastics are shown in Table 2-5. 

In each case the section is designed to keep the deflection to less than 2 in. in 16 in. for a design life of 5 years and the extreme fiber stress is kept to a value less than the yield strength of the material. The first step in the analysis is to determine the necessary section to resist the bending load using the short-term tensile and compressive strength and modulus values. The extreme fiber stress is calculated for these sections to determine that the chair will not break when deflected. 

On the other hand, the addition of fibers may cause undesired properties of the cement [1759]. Fibers can actually increase pore and fracture systems in latex cements. The amount of fibers in a fiber seal cement influences the porosity and permeability while affecting compressive strength. During acid treatment of the formation, the fibers in the cement can be easily dislodged and extracted from the cracks, leaving pore spaces behind. 

A totally unexpected observation was made when the compression strength of (0.1% by volume) fluorinated fiber concrete increased from about 31 MPa (unfilled) to about 38.6 MPa (filled with fluorinated fibrillated tape). This observation is in contrast to published results31 that PP fibers do not enhance compressive strength. 

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