The goal of micromechanics and analysis is to use the predictive methodology to develop tailored composites and also to make accurate predictions of their performance in service. This article reviews results derived from micromechanics analyses, based on finite-element method of unidirectional fiber reinforced metal matrix composites (MMCs). It discusses the elastic deformation and elastic-plastic deformation analysis of discontinuously reinforced MMCs. The article provides an overview of analysis of strength, fatigue, and fracture toughness for macromechanics fiber-reinforced and discontinuous reinforced composites.

Additive manufacturing produces a change in the shape of a substrate by adding material progressively. This article discusses the simulation of laser deposition and three principal thermomechanical phenomena during the laser deposition process: absorption of laser radiation; heat conduction, convection, and phase change; and elastic-plastic deformation. It provides a description of four sets of data used for modeling and simulation of additive manufacturing processes, namely, material constitutive data, solid model, initial and boundary conditions, and laser deposition process parameters. The article considers three aspects of simulation of additive manufacturing: simulation for initial selection of process parameter setup, simulation for in situ process control, and simulation for ex situ process optimization. It also presents some examples of computational mechanics solutions for automating various components of additive manufacturing simulation.

This article provides an explanation on how crystal plasticity is implemented within finite element formulations by the use of physical length scales: crystal scale and continuum scale. It provides theoretical formulations for kinematic framework for deforming crystals and polycrystals, elastic and plastic behaviors of single crystals, refinements to the single-crystal constitutive, and crystal-scale finite-element. The article also presents examples that illustrate the capabilities of the formulations at the length scales.

Hardness testing is perhaps the simplest and the least expensive method of mechanically characterizing a material. This article provides an overview of the principles of hardness testing. It compares Brinell with Meyer hardness testing and hardness testing of fully cold worked metals with fully annealed metals. The article discusses the plastic deformation of ideal plastic metals under an indenter, by a flat punch, and by spherical indenters. The classification of the hardness tests using various criteria, including type of measurement, magnitude of indentation load, and nature of the test, is also provided.

A characteristic feature of bending is the inhomogeneous (nonuniform) nature of the deformation. Therefore, in a bent specimen, the strain and stress at a given point are dependent on the location of the point with respect to the neutral axis of the cross-sectional area of the specimen. This article discusses the stress-strain relationships, strain curvature, and stress-moment equations for elastic, noncylindrical, elastic-plastic, and pure plastic bending conditions. It also reviews the distribution of residual stress and springback.

Shot peen forming is a manufacturing process in which local compressive residual stresses form thin sheet metals and structural components in one or more dimensions. This article discusses the principle of the process with an emphasis on fundamental mechanisms. It presents the basic considerations in the simulation of shot peen forming and provides information on single impact and multiple-impact peening simulations. The article describes the equipment and tooling used in the process. It also analyzes the influence of process parameters on shot peen forming and illustrates possible shapes and contours, which are producible by shot peen forming. The article concludes with a table that presents typical peen forming applications in the aircraft and aerospace industries.

This article describes a method to predict mechanical properties of cast iron materials and illustrates how to use the predictions in computer-aided tools for the analysis of castings subjected to load. It outlines some ways to predict the hardness and elastic modulus of cast iron without going into dislocation theory. The article discusses modeling of hardness in cast iron based on a regular solution equation in which the properties of each phase depend on chemical composition and coarseness. It describes the evaluation of material parameters from the tensile stress-strain curve. The article concludes with an illustration of a finite-element method (FEM) model containing heterogeneous mechanical properties using local material definitions.

This article discusses the deformation and viscoelastic characteristics of plastics as polymeric materials, focusing on the test methods used for the evaluation of their mechanical properties, methods available for analytically predicting the deformation response of polymers, and the effect of viscoelasticity on the test methods used. Two common ways of evaluating viscoelasticity of plastics are by means of creep experiments and dynamic mechanical experiments. Graphic or tabular analysis of test data, time-temperature superposition, and empirical correlation methods are commonly employed for analytical prediction of deformation characteristics of polymers.

This article describes the viscoelastic behavior of plastics in their solid state only, from the standpoint of the material deforming without fracturing. The consequences of viscoelasticity on the mechanical properties of plastics are described, especially in terms of time-dependencies, as well as the dependence of the viscoelastic character of a plastic on chemical, physical, and compositional variables. By examining the viscoelastic behavior of plastics, the information obtained are then applied in situations in which it may be important to anticipate the long-term properties of a material. This includes assessing the extent of stress decay in materials that are pre-stressed, the noise and vibration transmission characteristics of a material, the amount of heat build-up in a material subjected to cyclic deformation, and the extent a material can recover from any prior deformation. Several qualitative graphs are presented, which highlights the possible differences in the viscoelastic behavior that can exist among plastics.

Compression tests are used for subscale testing and characterizing the mechanical behavior of anisotropic materials. This article discusses the characteristics of deformation during axial compression testing, including deformation modes, compressive properties, and compression-test deformation mechanics. It describes the procedures for the use of compression testing for the measurement of the deformation and fracture properties of materials. The article provides a detailed discussion on the technique involved in determining the stress-strain behavior of metallic materials based on the ASTM E 9, "Compression Testing of Metallic Materials at Room Temperature." It also reviews the factors that influence the generation of test data for tests conducted in accordance with the ASTM E 9 and the capabilities of conventional universal testing machines for compression testing.

In the case of steels, heat treatment plays a fundamental role because no other process step can manipulate the microstructure in order to fulfill such a wide variety of possible in-service conditions. This article addresses heat treatment with regard to hardening and subsequent tempering of steel components in order to optimize tribological properties. It focuses on the heat treatment of tempering and bearing steels and on volume changes that take place due to phase transformations. Plastic deformations that occur due to shrinking and phase transformation are also discussed. The article also describes the generation of thermal, transformation, and hardening residual stresses.

Bending is a common metalworking operation to create localized deformation in sheets (or blanks), plates, sections, tubes, and wires. This article emphasizes on the bending of sheet metal along with some coverage on flanging. It informs that variations in the bending stresses cause springback after bending, and discusses the variables and their effects on springback, as well as the methods to overcome or counteract them. These methods include overbending, bottoming or setting, and stretch bending. The article provides information on elastic bending, non-cylindrical bending, elastic-plastic bending, and pure plastic bending. Sheet metal bendability is a critical factor in many forming operations. The article illustrates the derivation of two relevant bend-ductility equations.

This article focuses on mechanical behavior of materials under conditions of uniaxial tension and compression. The emphasis is on mechanical behavior during the engineering tension test, which is used to provide basic design information on the strength of materials and as an acceptance test for the specification of materials. The article presents mathematical expressions for a flow curve of many metals in the region of uniform plastic deformation. It explains that the rate at which strain is applied to the tension specimen has an important influence on the stress-strain curve. The point of necking at maximum load can be obtained from the true stress-true strain curve by finding the point on the curve having a subtangent of unity. The article concludes with an overview of the ductility measurements performed by notch tensile and compression tests.

Torsion tests can be carried out on most materials, using standard specimens, to determine mechanical properties such as modulus of elasticity in shear, yield shear strength, ultimate shear strength, modulus of rupture in shear, and ductility. This article discusses the torsional deformation of prismatic bars of circular cross-section and torsional response of prismatic bars of noncircular cross-section. It analyzes the elastic deformation, plastic deformation, and the effect of strain rate on plastic deformation. The article describes the theory of anisotropy in plastic torsion and the various components of a torsion testing machine. These include drive system, test section, torque and rotational displacement transducers, and rigid frame.

This article is a compilation of terms related to mechanical testing and evaluation of metals, plastics, ceramics, and composites.

This article outlines a general approach to develop a coupled electrical-thermal-mechanical analysis for the resistance spot welding process. It provides information on the discretization of sheet-electrode geometry and distribution of contact resistivity along the sheet-sheet and electrode-sheet interfaces. The distribution can be estimated based on the discretized geometry used for the numerical modeling. The article also details the results obtained from this modeling.

A newly developed theory on plasticity makes it possible to include elastic effects, which play a major role when using blunt hardness indenters. This article reviews the new theory and explains several phenomena associated with practical hardness testing. In the indentation hardness test, a blunt indenter that approximates a flat punch is forced into a plane surface. The effective cone angle for most indenters is such that some upward flow results even when there is sufficient material surrounding the indenter to provide a full elastic constraint. When loaded by a blunt indenter, materials with high values of Young's Modulus of Elasticity/uniaxial flow stress (E/Y) (metals) appear to develop a Hertzian stress distribution over the contact. In contrast, materials with low values of E/Y (glasses and polymers) develop a uniform distribution of stress.

There are many different types of polymeric materials, ranging from glassy to semicrystalline polymers and even blends. Their mechanical properties range from pure elastic with very high strains to fracture (elastomers) to almost pure linear elastic (Hookian behavior) with low strains to fracture (glassy polymers). This article provides an overview of historical development of fracture behavior in polymers. It discusses the processes involved in three fracture test methods for polymers, namely linear elastic fracture mechanics, elastic-plastic fracture mechanics, and post-yield fracture mechanics.