Search results

This paper aims to study the influence of different reinforcement methods on crack monitoring characteristics of eddy current array sensors, and the sensors with two different reinforcement methods, SUS304 reinforcement and permalloy reinforcement, are proposed.

First, the finite element model of the sensor is established to analyze the influence of the reinforcement plate’s electromagnetic parameters on the crack identification sensitivity. Then, the crack monitoring accuracy test of sensors with two reinforcement methods is carried out. Finally, the fatigue crack monitoring experiments with bolt tightening torques of 45 and 63 N · m are carried out, respectively.

In this study, it is found that the crack identification sensitivity of the sensor can be improved by increasing the relative permeability of the reinforcement plate. The crack monitoring accuracy of the sensors with two different reinforcement methods is about 1 mm. And the crack identification sensitivity of the sensor reinforced by permalloy reinforcement plate is significantly higher than that of the sensor reinforced by SUS304 reinforcement plate.

The sensor reinforced by reinforcement plate can work normally under the squeezing action of the bolt, and the crack monitoring sensitivity of the sensor can be significantly improved by using the reinforcement plate with high relative permeability.

This paper aims to develop of magnetic field controlled friction braking technology, a novel brake friction material with magnetic was designed and prepared in this paper.

The permalloy, a soft magnetic material, was selected as an additive to design and prepare the magnetic brake material. The friction, wear performance and permeability of each brake pads were investigated by experiments. By choosing the performance of friction coefficient fluctuation, friction coefficient deviation and mean wear rate as optimization parameters, the formulation of the magnetic friction material was optimized based on Fuzzy theory by using analytic hierarchy process methods and SPSS software.

The results showed that the developed soft magnetic friction material has not only superior friction coefficient, permeability and inferior wear rate but also good physical and mechanical properties.

Permalloy powder was added to the formulation of friction material to achieve a new functional friction material with high magnetic permeability. It is believed that this research will be of great theoretical and practical significance to develop both new brake materials and active control technology of the braking process in the future.

Describes the design and operating principles of fluxgate sensors and magnetometers. Polarity determination and compensation for temperature and high frequency (> 100Hz) alternating magnetic fields are also discussed.

In many systems which utilise magnetic components, e.g., miniaturised DC‐DC converters, PCMCIA cards, and modem stand‐off transformers, the magnetic device is the largest single component in the package. Surface‐mount magnetic devices may be unacceptably thick where low profiles are required. The authors's approach to this problem is to use micromachining techniques to realise inductors and transformers built into the multilayer structure of a multi‐chip package, allowing compact integration with chips, sensors and other components. Microinductors and micro‐transformers composed of thick cores and multiwinding conductors have high inductance, high saturation current, and low resistance compared with previous integrated inductors. The total size of the microinductive device is 4 mm ×4 mm× 0.145 mm, having 156 turns of multilevel electroplated copper coils (40 μm thick) and electroplated permalloy magnetic core (35 μm thick). These devices have inductances up to 1.5 μH and current‐carrying capability of up to 3A steady DC current, making them applicable to power converters. The processing steps chosen are all low‐temperature, which allow the use of low‐cost substrates such as MCM‐L compatible materials.

The paper aims to explain the operating principles of fluxgate magnetometers.

The approach is to describe the uses of ring fluxgate magnetometers and their operating principles.

The operating principles of fluxgate magnetometers are poorly understood and their applications potential seriously undervalued. An increasing number of everyday applications relying on sensing and fluxgates, in conjunction with modern analogue and micro‐controller electronics, represent unique value in implementing a variety of low‐cost, precise and absolute sensing elements. As magnetometers they are small, robust, reliable, low‐cost and can resolve flux densities to nano Teslas. This can be exploited to make a variety of sensors which are precise, inherently non‐contact and, for rotary sensing, have full 360° operation.

The paper illustrates how fluxgate magnetometers can form the basis for a variety of robust, reliable, non‐contact industrial sensors.

THE annual production of nickel is small in comparison with that of the common industrial metals, iron and steel, copper, lead, zinc and aluminium, but it is a metal of first class engineering importance because it is mainly used in the form of relatively small additions which have a pronounced influence on the properties of other metals, or in the manufacture of alloys with rather unique properties. Thus nickel finds its way into many branches of the metallurgical industry and the alloys in which it is present have numerous uses in most branches of engineering.

This paper aims to investigate a novel giant magnetostrictive (GM) force sensor using Terfenol-D rod.

First of all, principle of GM force sensor based on positive magnetostriction of Terfenol-D is presented. Then, design procedure of the GM force sensor is stated. Magnetic properties such as B-H curve and permeability of Terfenol-D are measured by a novel experimental setup and the results are used in analytical model, sensitivity estimation and numerical simulations. Then, an analytical model is presented and a numerical simulation using CST Studio Suite 2011 software is done. So as a result of numerical simulations, optimum geometry of the GM force sensor is obtained related to the condition in which the GM force sensor has highest sensitivity. After that, the sensor is fabricated using the simulation results and is tested by means of an experimental setup. Characteristic curve of the GM force sensor in several conditions is measured and the optimum operational condition is obtained considering highest sensitivity condition of the sensor. Also operational diagrams of the GM force sensor is plotted in loading and unloading conditions. Characteristics of the GM force sensor in optimum condition are presented.

It was found that the GM force sensor has maximum sensitivity and maximum linearity in 0.8A current, which can be known as optimum condition of application. In this sensor, maximum sensitivity is 0.51 mV/N (while current is 0.8A), which is highest among older investigations.

At last, theoretical, numerical and experimental results are compared and the criteria for magnetostrictive sensor design are presented.

The magnetic field generated or disturbed by an object is often overlooked when we need to inspect or detect it. In this tutorial Steve Macintyre describes the fundamental design principles of a range of magnetic field sensors.

The Giant MagnetoResistance (GMR) effect, discovered in France in 1988, has already been applied in magnetic sensors and has promise in other applications. The rapid acceptance of this technology is due to GMR’s unique characteristics such as high sensitivity, good temperature stability, and excellent linearity over a wide sensing range. In this article GMR materials are described as are their application in magnetic field sensors. New GMR structures utilizing spin valves and spin dependent tunneling (SDT) will offer even more potential for expanding the horizon of solid state magnetic sensing. Comparisons are made to sensors using conventional technology. Integrated GMR sensors that have signal conditioning and output electronics monolithically integrated with the sensor offer further uses of this new technology. Beyond the sensor itself, other control system functions have the potential for using the same GMR materials to make magnetic isolators and nonvolatile memories.