Search Results for area-amplitude blocks

This article discusses the inspection/reference standards that are absolutely critical for proper application of ultrasonic inspection systems. Many of the standards and specifications for ultrasonic inspection require the use of standard reference blocks. The article lists the variables that should be considered when selecting standard reference blocks and describes the three types of standard blocks ordinarily used for calibration or reference: area-amplitude blocks, distance-amplitude blocks, and blocks of the type sanctioned by the International Institute of Welding. It reviews the determination of area-amplitude and distance-amplitude curves of a straight-beam pulse-echo ultrasonic inspection system. The article discusses the three principal conventional manual ultrasonic sizing techniques: 6 dB drop technique, maximum-amplitude technique, and 20 dB drop technique. It provides information on the dimension-measurement applications of ultrasonic inspection methods.

Time-of-flight diffraction (TOFD) is an ultrasonic technique used to detect diffracted waves from crack tips and to size the cracks from the arrival times of those waves. This article discusses the basic considerations and provides information on probe selection, gain setting, and instrumentation of TOFD. It describes the numerous effects that result from modifying the probe characteristics. The article provides the American Society of Mechanical Engineers (ASME), the European Committee for Standardization (CEN), and the International Standardization Organization (ISO) recommendations for the reference blocks according to applicable codes and standards. It also provides the ASME, CEN, and ISO recommendations for examination of welds. The article concludes with information on the interpretation and analysis of TOFD images with an aid of sizing algorithms.

Surface damage from sliding contact is related to the adhesion of mating surfaces in contact. This article describes the methods for evaluation of surface damage caused by sliding contact. It defines adhesive wear in terms of asperity, cold welding, galling, scuffing, seizure, and wear coefficient. The article discusses various galling testing methods, such as button-on-block galling test, pin-on-flat galling test, and threaded connection galling test. It provides an overview of fretting wear that occurs between two tight-fitting surfaces subjected to a cyclic, relative motion of extremely small amplitude. The article also reviews the fretting rig for investigating fretting wear.

This article considers the two primary methods used for ultrasonic inspection: pulse-echo and the transmission methods. Pulse-echo inspection can be accomplished with longitudinal, shear, surface (Rayleigh), or Lamb (plate) waves using a diverse range of transducers. The article discusses the principles of each of these inspection methods. It describes the applications and the basic data formats for single-element transducer-based systems, including A-scans, B-scans, and C-scans. The article provides information on electronic equipment used for ultrasonic inspection. It also describes how specific material conditions produce and modify A-scan indications. The article provides information on the controls and their functions for the display unit of the electronic equipment. It describes the techniques used for the identification and characterization of flaws, namely, surface (Rayleigh) wave and ultrasonic polar scan techniques.

This article discusses several examples of fatigue load histories that intentionally create artificial fracture-surface markings during testing such that they are measurable by post-test quantitative fractography (QF). It reviews a number of methods for providing fatigue fracture-surface markers to aid QF of fatigue crack growth (FCG). These methods are based on load changes, including reordering the basic load histories and/or adding loads to them. The article also provides some guidelines for obtaining recognizable FCG markers for a variety of load histories and crack-growth regimes for coupons, components, and, particularly, full-scale fatigue tests.

The ultrasonic machining (USM) process consists of two methods, namely, ultrasonic impact grinding and rotary USM. This article lists the major ultrasonic components that are similar to both rotary USM and ultrasonic impact grinding. It also provides schematic representations of the components used in rotary USM and ultrasonic impact grinding. The article describes the operations of the components of the rotary ultrasonic machine and ultrasonic impact grinding machine. It discusses the applications of the rotary ultrasonic machine: drilling, milling, and surface grinding. The article concludes with information on machining characteristics of ultrasonic impact grinding.

This article describes the applications, methods, and limitations of five principal nondestructive test methods, namely, penetrant testing, magnetic-particle testing, eddy current testing, radiographic testing, and ultrasonic testing. The article also provides guidance for the method selection for respective applications.

Vibrothermography, also known as sonic thermography, sonic infrared (IR), thermosonics, and vibroacoustic thermography, is a nondestructive evaluation (NDE) technique for finding cracks and delaminations through vibration-induced heating. This article describes the four parts of the vibrothermography process: vibration of the specimen by a transducer; conversion of vibrational energy into heat by a crack, delamination, and other contacting surfaces; conduction of the heat to an external surface; and infrared detection of the heat with a thermal camera.

The electrical discharge machining (EDM) process is used for machining dies because of its ability to machining difficult geometries or materials with poor machinability. This article provides a discussion on the fundamentals of electrical discharge erosion and the principles of EDM and orbital-movement EDM. It discusses various aspects of wire EDM in machining dies and provides an overview of the materials used in EDM electrodes. The article concludes with a discussion on electrochemical machining.

Erosion, cavitation, and impingement are mechanically assisted forms of material degradation that often contribute to corrosive wear. This article identifies and describes several tests that are useful for ranking the service potential of candidate materials under such conditions. The tests, designed by ASTM as G32, G73, G75, and G76, define specimen preparation, test conditions, procedures, and data interpretation. The article examines the relative influence of various test parameters on the incubation and intensity of cavitation, including temperature, pressure, flow velocity, and vibration dynamics. It concludes with a discussion on data correlations and the relationship between laboratory results and service expectations.

Quantitative fractography (QF) is the examination and characterization of fracture surfaces of failed or broken-open components and specimens. This article provides examples of the application of QF to evaluate real-life fatigue failures and also a comprehensive guideline chart for detecting and measuring fatigue striations and progression markings, with examples.

This article discusses the microstructural processes that take place during plastic deformation and presents a plain phenomenological and general description of the cyclic stress-strain (CSS) response. It emphasizes the microstructural aspects of cyclic loading on single-phase materials tested in initially soft, dislocation-poor conditions resulting from a prior heat treatment. The article discusses deformation-induced phase transformations in austenitic stainless steels and commercial age-hardened aluminum alloys. It describes the interaction of dislocations and the strengthening of second-phase particles. The article also provides a description of the framework used to model the CSS response on a physical basis.

Ultrasonic inspection is a nondestructive method in which beams of high-frequency acoustic energy are introduced into a material to detect surface and subsurface flaws, to measure the thickness of the material, and to measure the distance to a flaw. This article provides a detailed account of ultrasonic flaw detectors, including ultrasonic transducers and types of search units and couplants. The article describes pulse-echo and transmission inspection methods and data interpretation. The general characteristics of ultrasonic waves and the factors influencing ultrasonic inspection are also addressed. The article concludes with a review of the advantages and disadvantages of ultrasonic inspection compared with other methods applications of the technique.

The ultrasonic additive manufacturing (UAM) process consists of building up solid metal objects by ultrasonically welding successive layers of metal tape into a three-dimensional shape with periodic machining operations to create detailed features of the resultant object. This article provides information on the materials, welding parameters, process consumables, procedures, and applications of the UAM. It describes the methods for determining metallurgical and mechanical properties of solid metal parts to assess the range of materials and applications for which the process is suited. These methods include peel testing, push-pin testing, and microhardness/nanohardness testing. The article also reviews the issues to be addressed in maintaining UAM fabrication quality.

This article discusses the fundamentals and operating principles of the following acoustic microscopy methods: scanning laser acoustic microscopy, C-mode scanning acoustic microscopy, and scanning acoustic microscopy. It describes the applications of acoustic microscopy for detecting defects in metals, ceramics, glasses, polymers, and composites with examples.