Search Results for sensitivity tests

This article provides guidelines for the assessment of model quality in materials science and engineering. It discusses the fundamentals of model quality assessment and the calibration of mechanistic material models. The article reviews the considerations for the model verification during software implementation planning to identify suitable programs, software components, and programming languages. It describes the validity tests used in model validation, including boundary-value tests, degenerate problem tests, sensitivity tests, and benchmarking. The article also presents an example of model calibration, verification, and validation for the prediction of martensite start temperature of steels.

This article provides information on the classification, microstructure, castability and section sensitivity of gray iron. It describes properties of the test bar and provides a short note on fatigue limit in reversed bending. Although the ASTM size B test bar is the bar most commonly used for all gray irons from classes 20 to 60, ASTM A 48 provides a series of bar sizes, and the user can select the bar sizes that best approximates the cooling rate in the critical section of the casting.

ASTM specification A 48 classifies gray irons in terms of tensile strength. The usual microstructure of gray iron is a matrix of pearlite with graphite flakes dispersed throughout. Section sensitivity effects are used in the form of a wedge test in production control to judge the suitability of an iron for pouring a particular casting. Mechanical property values obtained from test bars are sometimes the only available guides to the mechanical properties of the metal in production castings. Gray iron castings are used widely in pressure applications such as cylinder blocks, manifolds, pipe and pipe fittings, compressors, and pumps. Where high impact resistance is needed, gray iron is not recommended. The machinability of most gray cast iron is superior to that of most other cast irons of equivalent hardness, as well as to that of virtually all steel. Gray iron is used widely for machine components that must resist wear.

Complete vehicle accelerated corrosion testing on the proving ground is a mandatory testing tool among vehicle manufacturers around the globe. This article focuses on creating some awareness of the difficulty in applying reliable corrosion tests for all corrosion-sensitive automotive systems at once. It describes the various factors for a complete vehicle testing, including wear from road grit, dirt, salt load, elevated temperatures, and mechanical effects such as chafing and fretting. The article discusses the four main test blocks, namely, driving sequence on various proving ground tracks, exposure of the vehicle in one or more ways to road deicing salts, static exposure to forced climatic conditions, and additional elements such as operating the mechanical systems of the vehicle, car washes, and so forth. It concludes with information on the major advantages and drawbacks of a full-service-life test.

This article begins with an overview of classes and applications of gray iron. It discusses the castability of gray iron in terms of section sensitivity and fluidity. The article provides information on the dimensions of prevailing sections recommended for gray irons and reviews the properties and specifications of test bar. Properties of gray iron, such as fatigue limit, pressure tightness, impact resistance, machinability, and dimensional stability, at both room and elevated temperature, are reviewed. Wear behavior of gray iron castings during sliding contact under conditions of normal lubrication is also discussed. The article evaluates the use of alloys and heat treatment to modify as-cast properties. It concludes with information on the physical properties of gray iron castings.

Case depth is the normal distance from the surface of the steel to the start of the core. Measurement of case depth is highly sensitive to the type of case hardening, original steel composition, quenching condition, and even to the testing method. This article describes the various methods of measuring case depth in steels, including chemical methods such as the combustion analysis and spectrographic analysis, microhardness test method, macroscopic and microscopic visual methods, and nondestructive methods. It contains a table that provides approximate equivalent hardness numbers for steel.

This article addresses some established protocols for characterizing thermoplastics and whether they are homogeneous resins, alloyed, or blended compositions or highly modified thermoplastic composites. It begins with a discussion on characterizing mechanical, rheological, and thermal properties of polymer. This is followed by a section describing molecular weight determination using viscosity measurements. Next, the article discusses the use of cone and plate and parallel plate geometries in melt rheology. It then reviews the processes involved in the analysis of thermoplastic resins by chromatography. Finally, the article covers three operations of thermoanalysis, namely differential scanning calorimetry, thermogravimetric analysis, and thermomechanical testing.

Thermal inspection comprises all methods in which heat-sensing devices or substances are used to detect irregular temperatures. Inspection of workpieces can be used to detect flaws and undesirable distribution of heat during service. Though there are several methods of thermal inspection and many types of temperature-measuring devices and substances, this article focuses only on thermography, which is the mapping of isotherms, or contours of equal temperature, over a test surface, and on thermometry, which is the measurement of temperature. Thermography techniques can be classified as contact thermographic methods using cholesteric liquid crystals, thermally quenched phosphors, and heat-sensitive paints, and noncontact techniques using hand-held infrared scanners, high-resolution infrared imaging systems, and thermal wave interferometer systems. Contact thermometric inspection devices include bolometers, thermocouples, thermopiles, and meltable substances, whereas radiometers and pyrometers come under the noncontact category.

A corrosionist refers to a corrosion engineer, a corrosion technician, a corrosion scientist, a chemist, a physicist, an electrical engineer, a mechanical engineer, a coatings or plastics salesperson, a corrosion consultant, or a plant operator. This article presents an overview of statistical inference and addresses the commonly used statistical tools and tests. It describes the science and engineering of materials, including metals, polymers, and ceramics. The article explores the principles of various surface-sensitive techniques and the usefulness and limitations of these techniques. The techniques are divided into those that provide insight into surface topography and surface structure, and those that provide understanding of chemical nature and identity. The article presents a list of web sites and print media addressing corrosion and related topics in five different areas: societies and associations; corrosion standards, specifications, and recommended practices; sources of corrosion information; corrosion databases and data compilations; and other web resources.

Guided wave testing (GWT) is a method of nondestructive evaluation for the inspection of pipelines. This article focuses mainly on explaining GWT as it is applied in routine established use, covered by standards, in the oil and gas industry and also introduces some of the other contexts in which its use is growing in other evolving applications. It discusses the various guided wave modes and their selection criteria. The article provides information on considerations for mode control and the sensitivity of the GWT to the defect. It also shows some examples of advanced GWT.

This article describes the role of the full-scale testing in assessing composite structural systems of aircraft and qualifying them for in-service use. The typical full-scale tests include static, durability, and damage tolerance. The article discusses the parameters to be considered when developing the basic requirements for the static test. These parameters consist of material considerations, moisture and temperature effects, structure size, load application alternatives, instrumentation requirements, test procedure considerations, ultimate load requirements, and test results correlation. The basic requirements common for durability and damage tolerance tests, including environmental effects and inspection requirements, are also discussed.