Ultrasonic measurement models for surface wave and plate wave inspections

A complete ultrasonic measurement model for surface and plate wave inspections is obtained, where all the electrical, electromechanical, and acoustic∕elastic elements are explicitly described. Reciprocity principles are used to describe the acoustic∕elastic elements specifically in terms of an integral of the incident and scattered wave fields over the surface of the flaw. As with the case of bulk waves, if one assumes the incident surface waves or plate waves are locally planar at the flaw surface, the overall measurement model reduces to a very modular form where the far‐field scattering amplitude of the flaw appears explicitly

Ultrasonic phased array system modeling-issues and solutions

In modeling ultrasonic phased array inspection systems one needs to characterize the electrical and electromechanical components of the system and the radiation properties of the individual array elements since both of these properties are important in being able to model the overall response of the array to any flaws present. Models for determining each of these elements will be obtained and issues unique to phased array systems will be discussed

Transmission of an Ultrasonic Beam Through a Fluid-Solid Interface

In immersion ultrasonic testing, a beam of sound must pass through a liquid-solid interface before it can interact with subsurface defects. In modern quantitative NDE studies, it is essential to know the beam properties in the solid so that flaw scattering variations, transducer diffraction corrections, etc. can be estimated. Using high frequency asymptotics and the method of stationary phase, we show here that analytical expressions can be derived for the wavefield radiated by a piston transducer, where the transducer is oriented normal to a plane liquid-solid interface (Fig. 1). In the main beam of the transducer these expressions will be shown to be equivalent to the solutions Schoch obtained for a single fluid medium [1]

Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size

The steel damageability simulation under random loading by the power, energetical and strain fracture criterions

Effort to describe effect of variable amplitude loading character on fatigue damage cumulation is committed for a metal material of a structural part. It is proposed to quantify the influence of loading character on durability life via damage model incorporating the nonstationarity factor and the spectrum fullness factor. Experimental evidence and analytical results of the proposed model are correlated

Ultrasonic flaw sizing—An overview

The time-of-flight diffraction (TOFD) technique is one of the most common sizing methods in practical use by industry today. This method was developed over 40 years ago and is based on the technology and state of knowledge present at that time. A combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing

Anode Front-End Electronics for the Cathode Strip Chambers of the CMS Endcap Muon Detector

The front-end electronics system for the anode signals of the CMS Endcap Muon cathode strip chambers has about 183000 channels. The purposes of the anode front-end electronics are to acquire precise muon timing information for bunch crossing number identification at the Level-1 muon trigger system and to provide a coarse radial position of the muon track. Each anode channel consists of an input protection network, amplifier, shaper, constant-fraction discriminator, and a programmable delay. The essential parts of the electronics include a 16-channel amplifier-shaper-discriminator ASIC CMP16 and a 16-channel ASIC D16G providing programmable time delay. The ASIC CMP16 was optimized for the large cathode chamber size (up to 3 x 2.5 m2) and for the large input capacitance (up to 200 pf). The ASIC combines low power consumption (30 mW/channel) with good time resolution (2 - 3 ns). The del ay ASIC D16G makes possible the alignment of signals with an accuracy of 2.2 ns. This note presents the anode front-end electronics structure and results of the preproduction and the mass production tests, including radiation resistance and reliability tests. The special set of test equipment, techniques, and corresponding software developed and used in the test procedures are also described

Magnetic relaxation in the Bianchi-I universe

Extended Einstein-Maxwell model and its application to the problem of evolution of magnetized Bianchi-I Universe are considered. The evolution of medium magnetization is governed by a relaxation type extended constitutive equation. The series of exact solutions to the extended master equations is obtained and discussed. The anisotropic expansion of the Bianchi-I Universe is shown to become non-monotonic (accelerated/decelerated) in both principal directions (along the magnetic field and orthogonal to it). A specific type of expansion, the so-called evolution with hidden magnetic field, is shown to appear when the magnetization effectively screens the magnetic field and the latter disappears from the equations for gravitational field.Comment: 32 page