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Damage and Defect Types in Composites
Published in Heslehurst Rikard Benton, Engineered Repairs of Composite Structures, 2019
Composites and adhesively bonded structures have many advantages over conventional aircraft materials and constru ction methods, particularly in primary structures. These advantages include a high specific strength and stiffness, formability and a comparative resistance to fatigue cracking and corrosion. However, not forsaking these advantages, these materials and construction methods are prone to a wide range of defects and damage, which can significantly reduce the residual strength of the components. In this chapter is a review of the types of defects and damage found in composite structures, their failure modes and mechanisms, and a general representation of the defect.
Design Properties of Materials
Published in Robert L. Mott, Joseph A. Untener, Applied Strength of Materials, Sixth Edition SI Units Version, 2017
Robert L. Mott, Joseph A. Untener
Designers typically seek to produce products that are safe, strong, stiff, lightweight, and highly tolerant of the environment in which the product will operate. Composites often excel in meeting these objectives when compared to alternative materials such as metals, wood, and unfilled plastics. Two parameters that are used to compare materials are specific strength and specific modulus, defined as Specific strength is the ratio of the tensile strength of a material to its specific weight.Specific modulus is the ratio of the modulus of elasticity of a material to its specific weight.Because the modulus of elasticity is a measure of the stiffness of a material, the specific modulus is sometimes called specific stiffness.
Design Properties of Materials
Published in Robert L. Mott, Joseph A. Untener, Applied Strength of Materials, 2016
Robert L. Mott, Joseph A. Untener
Designers typically seek to produce products that are safe, strong, stiff, lightweight, and highly tolerant of the environment in which the product will operate. Composites often excel in meeting these objectives when compared to alternative materials such as metals, wood, and unfilled plastics. Two parameters that are used to compare materials are specific strength and specific modulus, defined as Specific strength is the ratio of the tensile strength of a material to its specific weight.Specific modulus is the ratio of the modulus of elasticity of a material to its specific weight.
Evaluation of fracture toughness of hybrid CNT/CFRP composites
Published in Mechanics of Advanced Materials and Structures, 2023
Mikhail Burkov, Alexander Eremin
Laminate composites made of high-strength fabrics constitute a very large class of materials having an extremely wide variety of applications. There is a huge combination of binders and reinforcing fibers resulting in materials ranging from cheap glass fiber reinforced polymers used in everyday life to very expensive carbon fiber composites applied for manufacturing of main load-bearing structures of novel aircrafts [1, 2]. A lot of researchers and engineers often address an excellent combination of mechanical and physical properties of carbon fiber-reinforced composites. Thus, such materials have outstanding specific strength and specific stiffness which are very demanded in aerospace industry with hard weight limitations. Another advantage consists in extended technological possibilities: the composite parts can be manufactured with tailored properties fitting the particular loading conditions; the number of joints can be significantly reduced by replacing them with adhesive bonding operations or producing larger scale parts as a whole (e.g., manufacturing of Boeing 787 fuselage).
Effects of graphene oxide on mechanical properties and microstructure of ultra-high-performance lightweight concrete
Published in Journal of Sustainable Cement-Based Materials, 2023
Hongyan Chu, Jianjian Qin, Li Gao, Jinyang Jiang, Fengjuan Wang, Danqian Wang
The specific strength is equal to the ratio of the mechanical strength of the material to its apparent density, which is a critical parameter used to reflect the lightweight and high strength of the materials. Sajedi et al. [61] prepared a high strength lightweight concrete, and its compressive strength and apparent density were 68 MPa, and 1960 kg/m³, respectively. Lu et al. [62] produced a high-performance lightweight concrete, and its compressive strength and apparent density were 89 MPa, and 2100 kg/m³, respectively. The compressive strength of UHPLC prepared by Umbach et al. [5] was 105 MPa, and its apparent density was 2070 kg/m³. Xie et al. [63] used ceramic sand to prepare UHPLC, and its compressive strength and apparent density were 106.0 MPa, and 1980 kg/m³, respectively. The UHPLC designed by Zhang et al. [64] had a specific strength of 0.055. The specific strength of ULC6 prepared in this work was 0.058. The specific strength of the above-mentioned cement-based materials was summarized in Figure 6. It could be seen from Figure 6 that the specific strength of ULC6 was higher than those of cement-based materials presented in the literature [5, 61–64], suggesting that the UHPLC prepared in this study could meet the requirements of both lightweight and high strength.
Determination of layerwise material properties of composite plates using mixed numerical–experimental technique
Published in Inverse Problems in Science and Engineering, 2019
Asim Kumar Mishra, Sushanta Chakraborty
Most high performance structural engineering applications demand high specific strength and stiffness of the materials used. Fibre Reinforced Plastics (FRP) is extensively used, mostly in layers to cater to this need and also to provide required dynamic performances [1] in service. The dynamic characteristics of any structure are functions of its geometry, material properties and boundary conditions. The material properties of such layered structures degrade over time due to service loads and various adverse environmental effects. It will be of advantage if such degradation can be determined accurately as and when required for FRP layered structures under service condition thus, can be useful for condition assessment and health monitoring. Material properties of FRP structures are initially assessed from static characterization tests on specially prepared samples during fabrication. Such a characterization process is very elaborate for layered constructions which employs a number of materials and is expected to have high scatter, so that prediction of a globally representative average material property will be difficult. The actual existing boundary conditions may also be substantially different from any classical description and may deviate even more over ages. It necessitates the application of a suitable non-destructive inverse technique that can accurately predict existing material properties layerwise as well as the boundary conditions together from conveniently measured dynamic responses. This has not been attempted so far on real-life structures.