Mechanical Properties of Composite Materials

Rusakov, V. V., in Structural and Mechanical Properties of Composite Materials, pp. 37-48, Sverdlovsk, Sci. Papers of Ural Sci. Center of Akad. Nauk USSR 1984... 

Fillers bring corrective amendments into mechanical properties of composite material independently from each other, namely presence of organic filler results in increase of durability, presence of inorganic filler keeps plasticity of systems almost for all investigated materials. 

Composites are solids made of more than one material type, designed to have enhanced properties compared with those of the separate materials themselves (see Sections 6.1.5, 6.2.4 and 6.4.5). The mechanical properties of composite materials are often difficult to obtain because of the complex microstructures found, especially in biological structures. However, in simple cases these can be modelled. 

The structure and properties of the fibre-matrix interface play a mayor role in the mechanical properties of composite materials too. The fibre can be used as reinforcement in composite materials since it is indicate that the length of fibre more length than critical length of the fibre. 

The mechanical properties of composite materials under the influence of "rule of mixtures". The alignment or orientation of the fibres in the composite materials can be divided on three type one-dimensional reinforcement, two-dimensional (planar) reinforcement and three-dimensional(random) reinforcement. The random orientation type of the isotropic but has greatly decreased reinforcing value(about one-third of the one-dimentional reinforced value). As the fibre orientation becomes more random, the mechanical properties in any one direction become lower. 

Mechanical interlocking of two surface, matrix-roughen fibre surface produce matrix faibre bond to be higher than the smooth surface fibre-matrix, and the mechanical properties of composite materials to be better than without mechanical treatment on surfaee of the palmyra and coir fibres. 

Yanovsky, Yu. G., Valiev, Kh. Kh., Kornev, Yu. V. Kamet, Yu. N., Boiko, O. V. Kosich-kina, K. R, Yumashev, O. B. The role of scale factor in estimation of the mechanical properties of composite materials with nanofillers. Nanomechanics Science and Technology An IntemationalJoumal, 1,3,187-211 (2010). 

Kerner [104] made the first sophisticated analysis of thermoelastic properties of composite media using a model which had been considered earlier by van der Poel for calculation of the mechanical properties of composite materials. Here the dispersed phase has been assumed for spherical particles. Kemer s model accounts for both the shear and isotactic stresses developed in the component phases and gives for the composite ... 

Ibarra L, Macias A, Palma E, Mechanical properties of composite materials consisting of short carbon fibre and thermoplastic elastomers, Kautschuk Gummi Kunstoffe, 48(3), 180-184, 1995. Jacobsen RL, Tritt TM, Guth JR, Ehrlich AC, Gillespie DJ, Carbon, 33(9), 1217-1221, 1995. Tibbetts GG, Doll GL, Gorkiewicz DW, Moleski JJ, Perry TA, Dasch CJ, Balogh MJ, Physical properties of vapour grown carbon fibres, Carbon, 31(7), 1039-1047, 1993. 

Oriented and liquid crystalline precursor oligomers produced in the early stage of Ts-LCPs syntheses make the manufacture of composites convenient and are utilized to solve the rheological problem. Liquid crystallinity of the precursor oligomer leads to the dense alignment and results in low bulk shrinkage in the curing process, that not only is helpful to simplify the manufacture, but also can improve the mechanical properties of composite materials. 

Toledo Filho et al. [32] studied the effect of a series of treatments on natural fiber and cement matrix in order to increase durability of cement mortars reinforced with sisal fibers. Based on results from their investigation, it was concluded that incorporation of sisal fibers significantly reduced mechanical properties of composite material. However, the mechanical properties of composite were maintained over time if the sisal fibers were immersed in a suspension of silica fume. This is because the silica fume particles contact the fiber and their size allows them to be located in smaller defects in the fiber, preventing that compounds such as calcium hydroxide, come into contact with the fiber and destroy it by growth of crystals. 

Notwithstanding the high mechanical properties of composite materials, a reinforcement intervention taking into account its use has to be carried out on those structural elements not showing special damages, which may prevent the transfer of stresses between the wall ashlars forming it. 

The use of FRP is convenient also in older metal constmctions, since the mechanical properties of composite materials are well suited to the stmctural features of buildings employing cast iron. The exceptional tensile strength of the fibers makes up for the low resistance of the cast iron and the corrosion resistance of both materials makes the intervention durable. The traditional techniques that rely on welding are unfavorable because fliey require flie complete disassembly of the work, along with an inevitable increase of costs and time consumption. It demonstrated, moreover, the effectiveness of flie application of FRP in improving the brittle behavior of cast iron. 

Nuriel H, Klein N and Marom G (1999) The effect of the transcrystalline layer on the mechanical properties of composite materials in the fiber direction, Compos Sci Technol 59 1685-1690. 

Xu H S, Li Z M, Yang S Y, Pan J L, Yang W and Yang M B (2005) Rheological behavior comparison between PET/HDPE and PC/HDPE microfibrillar blends, Polym Eng Sci 45 1231-1238. Nuriel H, Klein N and Marom G (1999) The effect of the transcrystalline layer on the mechanical properties of composite materials in the fiber direction. Compos Sci Technol 59 1685-1690. Sapoundjieva D, Denchev Z, Evstatiev M, Fakirov S, Stribeck N and Stamm M (1999) Transcrystallization with reorientation in drawn PET-PA12 blend as revealed by WAXS from synchrotron radiation, J Mater Sci 34 3063-3066. 

Porosity cannot be determined by one parameter, that is, by ratio of pore volume to total volume, because for most purposes it is necessary to separately consider pores of different kinds and dimensions in relation to mechanical properties of composite materials, and pores in cement paste may be classified according to various criteria. 

Guo et al. 5 ook resin matrix composites filled with SIC whiskers as an example and analyzed the effect of the inter-facial zone state on mechanical properties of composite materials by finite element method. They hold that when whiskers are randomly distributed in a resin matrix with a certain volume fraction, they demonstrate a periodic distribution from the statistical point of view. It is assumed that the SIC whisker-reinforced phase in resin matrix composites is arranged in one direction without considering the effect of whisker orientation, the analysis model can be simplified as a rotator shape with the large cylindrical part as the polymer matrix and the small cylindrical part as the whisker. Therefore, a three-dimensional problem turns into an axisymmetric problem, and only a quarter part of the body model is taken in the calculation. 

The outstanding mechanical properties of composite materials has been a key reason for their extensive use in structures. However, composites also have important physical properties, especially low, tailorable coefficient of thermal expansion (CTE) and high thermal conductivity, which are key reasons for their selection in an increasing number of applications. Key examples are electronic packaging and thermal management. 

FEM is a powerful numerical analysis tool used to predict mechanical properties of composite materials. Zeng et al. [48] resumed the necessary steps to implement FEM... 

Inorganic phases can be added to the different polymer matrices in the form of micron-sized or nanoscale particles or fibers. The size of the filler particles is an important parameter that affects the mechanical properties of composite materials. This is due to the marked microstructural differences introduced by the micron-sized or nanoscale fillers that contribute towards different interactions between the filler particles and the polymer matrix. In general, the introduction of nanoscale fillers with a desired morphology can increase the mechanical strength and stiffness of the composites in comparison to the properties of the neat polymer. The use of nanoscale degradable fillers such as bioactive glass or... 

Mathias Lindner - Head of R D, FACT GmbH, Germany. Mr. Lindner got his degree in Mechanical Engineering in 1997. He has been active in several research subjects in the field of long fiber-reinforced thermoplastics. His interests are especially in the field of mechanical properties of composite materials, as well as in the manufacturing methods of long fiber-reinforced thermoplastics. He holds several patents in the field of composite materials. 

---