Search Results for mechanical test

This article reviews the various types of mechanical testing methods, including hardness testing; tension testing; compression testing; dynamic fracture testing; fracture toughness testing; fatigue life testing; fatigue crack growth testing; and creep, stress-rupture, and stress-relaxation testing. Shear testing, torsion testing, and formability testing are also discussed. The discussion of tension testing includes information about stress-strain curves and the properties described by them.

Mechanical tests are performed to evaluate the durability of gears under load. Gear tooth failures occur in two distinct regions, namely, the tooth flank and the root fillet. This article describes the common failure modes such as scoring, wear, and pitting, on tooth flanks. Failures in root fillets are primarily due to bending fatigue but can be precipitated by sudden overloading (impact). The article presents contact stress computations for gear tooth flank and bending stress computations for root fillets. Specimen characterization is a critical part of any fatigue test program because it enables meaningful interpretation of the results. The article describes four areas of the characterizations: dimensional, surface finish/texture, metallurgical, and residual stress. The rolling contact fatigue test, single-tooth fatigue test, single-tooth single-overload test, and single-tooth impact test are some of the gear action simulating tests discussed in the article.

Mechanical properties are often the most important properties in the design and selection of engineering plastics. Temperature, molecular structure, crystallinity, viscoelasticity, and effects of environment, fillers and reinforcements are considered as the basic factors affecting the mechanical properties of engineering plastics. The testing methods for determining mechanical properties, including stress-strain test, modulus-directed tensile test, strength test, strength-directed tensile test, impact test, and dynamic mechanical test are discussed.

Testing of fiber-reinforced composite materials is performed to determine uniaxial tensile strength, Young's modulus, and Poisson's ratio relative to principal material directions, that helps in the prediction of the properties of laminates. Beginning with an overview of the fundamentals of tensile testing of fiber-reinforced composites, this article describes environmental exposures that often occur during specimen preparation and testing. These include exposures during specimen preparation, and planned exposure such as moisture, damage (impact), and thermal cycling techniques. The article also discusses the test procedures, recommended configurations, test specimen considerations, and safety requirements considered in the four major types of mechanical testing of polymer-matrix composites: tensile test, compression test, flexural test, and shear test.

Mechanical testing is an evaluative tool used by the failure analyst to collect data regarding the macro- and micromechanical properties of the materials being examined. This article provides information on a few important considerations regarding mechanical testing that the failure analyst must keep in mind. These considerations include the test location and orientation, the use of raw material certifications, the certifications potentially not representing the hardware, and the determination of valid test results. The article introduces the concepts of various mechanical testing techniques and discusses the advantages and limitations of each technique when used in failure analysis. The focus is on various types of static load testing, hardness testing, and impact testing. The testing types covered include uniaxial tension testing, uniaxial compression testing, bend testing, hardness testing, macroindentation hardness, microindentation hardness, and the impact toughness test.

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.

This article describes the tests for the common types of fabricated components and modeling of metal deformation. It provides an overview of component testing and briefly reviews the relationship of mechanical properties in the process of mechanical design for static loads, cyclic loads, dynamic loads, and high-temperature materials. The article describes the general properties related to monotonic stress-strain behavior of steels. It also discusses materials properties and operating stresses as well as other factors, such as part shape and environmental effects, which play significant roles in the design process of components.

This article discusses the standard test methods that can be applied to many types of welds: tension, bending, impact, and toughness testing. It provides information on four qualification stages, namely, the weld material qualification, base material qualification, the weld procedure qualification, and the weld service assessment. The article describes two general types of measurements for residual stress in welds: locally destructive techniques and nondestructive techniques. Locally destructive techniques include hole drilling, chip machining, and block sectioning. Nondestructive techniques include X-ray diffraction, neutron diffraction, Barkhausen noise analysis, and ultrasonic propagation analysis. The article concludes with an overview of weldability testing.

This article reviews the general mechanical properties and test methods commonly used for ceramics and three categories of polymers, namely, fibers, plastics, and elastomers. The mechanical test methods for determining the tensile strength, yield strength, yield point, and elongation of plastics include the short-term tensile test, the compressive strength test, the flexural strength test, and the heat deflection temperature test. The most commonly used tests for impact performance of plastics are the Izod notched-beam test, the Charpy notched-beam test, and the dart penetration test. Two basic test methods for a group or strand of fibers are the single-filament tension and tow tensile tests. Room temperature strength tests, high-temperature strength tests, and proof tests are used for testing the properties of ceramics.

An important activity in metalworking facilities is the testing of raw materials for characteristics that ensure the integrity and quality of the products made. This article reviews the common material parameters that can have a direct or indirect influence on workability and product quality. These include strength, ductility, hardness, strain-hardening exponent, strain-rate effects, temperature effects, and hydrostatic pressure effects. The article also reviews the material behavior characteristics typically determined by mechanical testing methods. It discusses various mechanical testing methods, including the tension test, plane-strain tension test, compression test, plane-strain compression test, partial-width indentation test, and torsion test. Aspects of testing particularly relevant to workability and quality control for metalworking processes are also described. Finally, the article details the various factors influencing workability in bulk deformation processes and formability in sheet-metal forming.

The purpose of accreditation is to evaluate and assure high-quality results from suppliers of products or services without incurring the costs associated with auditing each supplier. This article describes laboratory accreditation based on the general requirements of International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Guide 25, "General Requirements for the Competence of Calibration and Testing Laboratories." The Guide 25 is a balanced standard that addresses quality system requirements of ISO 9000 and the technical requirements needed to perform testing or calibration. The article describes an accreditation process that would enhance the international acceptance of test data for mechanical testing laboratories.

This article provides the general mechanical testing guidelines for the characterization of lamina and laminate properties. Guidelines are provided for tensile property, compressive property, shear property, flexure property, fracture toughness, and fatigue property test methods. The article also tabulates selected standards for lamina and laminate mechanical testing.

This article briefly introduces some commonly used methods for mechanical testing. It describes the test methods and provides comparative data for the mechanical property tests. In addition, creep testing and dynamic mechanical analyses of viscoelastic plastics are also briefly described. The article discusses the processes involved in the short-term and long-term tensile testing of plastics. Information on the strength/modulus and deflection tests, impact toughness, hardness testing, and fatigue testing of plastics is also provided. The article describes tension testing of elastomers and fibers. It covers two basic methods to test the mechanical properties of fibers, namely the single-filament tension test and the tensile test of a yarn or a group of fibers.