Sphere Packings, Lattices and Groups

American Society for Testing and Materials

Emerging trends in manufacturing such as light weighting, increased performance and functionality increases the use of multi-material, hybrid structures and thus the need for joining of dissimilar materials. The properties of the different materials are jointly utilised to achieve product performance. The joining processes can, on the other hand be challenging due to the same different properties. This paper reviews and summarizes state of the art research in joining dissimilar materials. Current and emerging joining technologies are reviewed according to the mechanisms of joint formation, i.e.; mechanical, chemical, thermal, or hybrid processes. Methods for process selection are described and future challenges for research on joining dissimilar materials are summarized.

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Joining of dissimilar materials

INTRODUCTION TO COMPOSITE MATERIALS Chapter Objectives Introduction Classi?cation Recycling Fiber-Reinforced Composites Mechanics Terminology Summary Key Terms Exercise Set References MACROMECHANICAL ANALYSIS OF A LAMINA Chapter Objectives Introduction Review of De?nitions Hooke's Law for Different Types of Materials Hooke's Law for a Two-Dimensional Unidirectional Lamina Hooke's Law for a Two-Dimensional Angle Lamina Engineering Constants of an Angle Lamina Invariant Form of Stiffness and Compliance Matrices for an Angle Lamina Strength Failure Theories of an Angle Lamina Hygrothermal Stresses and Strains in a Lamina Summary Key Terms Exercise Set References APPENDIX A: MATRIX ALGEBRA Key Terms APPENDIX B: TRANSFORMATION OF STRESSES AND STRAINS Transformation of Stress Transformation of Strains Key Terms MICROMECHANICAL ANALYSIS OF A LAMINA Chapter Objectives Introduction Volume and Mass Fractions, Density, and Void Content Evaluation of the Four Elastic Moduli Ultimate Strengths of a Unidirectional Lamina Coefficients of Thermal Expansion Coefficients of Moisture Expansion Summary Key Terms Exercise Set References MACROMECHANICAL ANALYSIS OF LAMINATES Chapter Objectives Introduction Laminate Code Stress-Strain Relations for a Laminate In-Plane and Flexural Modulus of a Laminate Hygrothermal Effects in a Laminate Summary Key Terms Exercise Set References FAILURE, ANALYSIS, AND DESIGN OF LAMINATES Chapter Objectives Introduction Special Cases of Laminates Failure Criterion for a Laminate Design of a Laminated Composite Other Mechanical Design Issues Summary Key Terms Exercise Set References BENDING OF BEAMS Chapter Objectives Introduction Symmetric Beams Nonsymmetric Beams Summary Key Terms Exercise Set References INDEX

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Mechanics of composite materials

Bonded repair of composite aircraft structures: A review of scientific challenges and opportunities

Measurement of fracture toughness for fiber compressive failure mode of UD composites under high rate loading

With the growing application of carbon-fibre reinforced polymers (CFRPs) in lightweight aerospace and transportation structures, it is essential and urgent to develop a comprehensive understanding of their response under various loading conditions to determine the design constraints. Under longitudinal tensile and compressive loading, the material behaviour is dominated by the fibre and presents a predominantly linear response. In contrast, transverse and shear loading may result in large nonlinear deformation prior to polymer matrix damage. Compared to fibre dominated behaviour, a response dominated by the matrix under shear loading can considerably limit the load-bearing capability and restrict the utilisation of composite materials. In the design of composite structures, lamina thickness and orientation are specified to meet the requirements of the working environment. In order to attain a detailed comprehension of the shear response of these parameters, an investigation into the effects of lamina thickness and orientation on the shear response of composite laminates was carried out in this work. Different ply thickness and ply orientation were represented by four composite lay-ups to characterise the material response of composite laminates under shear loading. The geometry of a V-notched rail shear specimen and testing method, presented in the American Society for Testing and Materials (ASTM) standard D7078/D7078M-05, was employed to perform the physical compact shear tests. A Digital Image Correlation (DIC) system was used to observe the strain evolution of the compact shear specimens. The load versus displacement and nominal stress versus strain curves were obtained from the experimental data. In addition, the nonlinear shear stress profile was defined using an exponential model based on the calculated nominal stress and measured strain. The shear modulus, shear strength and nonlinear shear response obtained from different composite lay-ups were compared. A good understanding of the relationship between shear response and lay-up thickness and orientation was achieved based on experimental and analytical results obtained in this study. Furthermore, the measured shear properties of the composite laminates were used to verify a high-fidelity computational damage model through the modelling of virtual v-notched rail tests. Good correlation was obtained between experiment and simulation results.

Studies on the effects of lamina thickness and orientation on the shear response of composite laminates

Dynamic properties at intermediate strain rate are inherently difficult due to the dynamic interactions between the test specimen and the test machine. These effects obscure the interpretation of test results and therefore can make the derivation of the material properties difficult and unprecise. Soft materials can be used within load introduction devices to mitigate the inertia effect that typically occurs in dynamic tests. In this paper, dynamic tensile tests were performed within the strain rate range of 0.1 s−1 to 400 s−1 on high strength steels. With the aim of evaluating the performance of damping materials in the slack adaptor, copper and acrylic tapes were used. Experimental results show that both damping materials may be used to effectively reduce the oscillations in the measured force signal. The outcome of this project will provide the test procedure for dynamic testing at intermediate strain rates, which can produce reliable test results for materials with low failure to strain.

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An Improved Load Introduction Technique for Dynamic Material Characterisation at Intermediate Strain Rate

Interlaminar crack onset and propagation in fibre-reinforced composites is here investigated in detail through the development of a micromechanics framework. The different dissipative effects that characterize crack propagation are assessed by using the appropriate constitutive material models. The phenomenon of delamination migration between angled plies is studied by embedding unit cells in-between homogenized plies. Different features associated with delamination migration are analyzed, such as the distribution of interlaminar shear stresses at the crack tip and the kink angles, aiding in the understanding of the complex phenomena linked to interlaminar crack migration. In addition, the influence of through-thickness compressive stress on the mode II interlaminar fracture toughness is studied and verified by comparing numerical predictions with experimental results, showing that the proposed computational framework represents a sound tool that can be used to better understand the micromechanics of interlaminar failure in advanced composite materials.

Micromechanical modelling of interlaminar damage propagation and migration

http://dspace.uevora.pt/rdpc/bitstream/10174/32906/1/Yoo_et_al_2022_preprint.pdf

Dynamic intralaminar fracture toughness characterisation of unidirectional carbon fibre-reinforced polymer composites using a high-speed servo-hydraulic test set-up

Giuseppe Catalanotti

Papers

Measurement of fracture toughness for fiber compressive failure mode of UD composites under high rate loading

Studies on the effects of lamina thickness and orientation on the shear response of composite laminates

An Improved Load Introduction Technique for Dynamic Material Characterisation at Intermediate Strain Rate

Micromechanical modelling of interlaminar damage propagation and migration

Dynamic intralaminar fracture toughness characterisation of unidirectional carbon fibre-reinforced polymer composites using a high-speed servo-hydraulic test set-up