An isotropic magnetic-field transducer based on the giant magnetic impedance effect

A comparative analysis of the giant magnetoimpedance effect and the results of a mathe- matic simulation are presented. This simulation was used for optimizing the topology of a wide-angle magnetic transducer equipped with a sensitive element that consists of two crossed Fe₃Co₆₇Cr₃Si₁₅B₁₂ amorphous ribbons that form different angles between them.     

A PVDF dynamic pressure gage

Technologies for manufacturing and poling the dynamic pressure gage based on ferroelectric polyvinylidene fluoride polymer are described. Results of theoretical and methodical investigations of the gage and pressure profiles measured with this gage behind the shock wave front in solids are presented.     

Averaging effects of a strain gage

Choosing the right strain gage for a measurement application requires selecting gages with the right characteristics for the job. In general, the strain gage is to be used to measure the strain at the center of the gage, but it inherently underestimates the peak strain when it is mounted in high stress gradient areas. This paper concerns itself with the averaging effects of a strain gage along gage filaments. The approach is unconventional in dealing with the orientation and size of the gage. The results provide insight into the averaging effect and selecting gages for measuring strains in areas of steep strain gradients. Dimensionless curves which can be used to estimate errors as well as enhance hole-drilling method results are presented. Practical recommendations are made for selecting gages for high strain gradient measurements.     

Evaluating the structure of a ferromagnetic material based on magnetic-field strength between the poles of an attached two-pole magnetizing device

The possibility for using a magnetic structoroscope with a two-pole permanent-magnet magnetizing device to test mechanical properties of stressed-deformed state of articles made of ferromagnetic materials has been investigated. Dependences of equipment readings on the geometrical dimensions of the structuroscope sensor and on the deformation of ferromagnetic material of a sample in tension in the elastic loading–unloading domain are presented for samples made of different ferromagnetic materials.     

A pulse magnetic-field generator for terahertz gyrodevices

A pulse magnetic-field generator producing pulse amplitudes up to 50 T with base durations of unities of milliseconds is described. The pulse magnetic field is obtained during discharging a capacitive storage through a thyristor-diode switch into a nitrogen-cooled solenoid. The repetition of the pulse amplitude of the current in the solenoid is ensured with an accuracy up to tenth of shares of a percent by stabilizing the precharge voltage of the storage and thermally stabling the solenoid. Using this generator, experiments for obtaining terahertz kilowatt-power radiation from 0.9- to 1.3-THz frequencies were successfully performed.     

减小箔式应变计热输出分散度的方法

箔式应变计的热输出及其分散度是影响测力、称重传感器性能的重要因素之一,本文提出一种减少箔式应变计热输出分散度的措施,以降低测力、称重传感器的零点温漂值,从而提高温度补偿效率和产品成品率。     

电阻应变片的温度自补偿及其他

电阻应变片也称电阻应变计,简称应变片或应变计。本文从普及的角度。试从应变片热输出的物理概念、应变片温度自补偿的原理、箔材电阻温度系数的选择原则、不同弹性体材料上应变片热输出的估算以及用应变片测定弹性体材料线膨胀系数的方法等相关方面的知识加以简要介绍,以供从事应变片及传感器技术的同仁参考。     

CL-639贴片胶的研制

本文介绍了传力贴片胶研制的思路、遇到的问题和解决方法,包括粘结性能好和防潮性能好的两种环氧树脂材料的优势互补取得的效果,最后摘录了这种贴片胶在传感器试验中的良好性能,以及使用这种贴片胶的传力应变计滞后检测得到优于国标A级品的数据。     

Computer-assisted methods for finding pulsed magnetic-field distributions near current-conducting objects

Time dependences are given for an electric voltage U(t) that is recorded across an inductive magnetic head when scanning a discontinuous magnetic carrier that has been subjected to pulsed magnetic fields of a linear inductor. The value of U(t) at each point of the carrier is determined by the amplitude of each pulse, the pulse direction, and the sequence of exposures. If a current-conducting object is present, this value also depends on the field pulse rise time. The phenomenon of hysteretic interference of a pulsed magnetic field (HI) is used. Digital images of pulsed magnetic fields, as well as computer-assisted methods for measuring these fields, finding their distributions, and processing observation results are presented.     

放射性液位计的常见故障及检测方法

论述放射性液位计的测量原理及对它的一般检测方法。     

Direct-current cathodic vacuum arc system with magnetic-field mechanism for plasma stabilization

Filtered cathodic vacuum arc (FCVA) deposition is characterized by plasma beam directionality, plasma energy adjustment via substrate biasing, macroparticle filtering, and independent substrate temperature control. Between the two modes of FCVA deposition, namely, direct current (dc) and pulsed arc, the dc mode yields higher deposition rates than the pulsed mode. However, maintaining the dc arc discharge is challenging because of its inherent plasma instabilities. A system generating a special configuration of magnetic field that stabilizes the dc arc discharge during film deposition is presented. This magnetic field is also part of the out-of-plane magnetic filter used to focus the plasma beam and prevent macroparticle film contamination. The efficiency of the plasma-stabilizing magnetic-field mechanism is demonstrated by the deposition of amorphous carbon (a-C) films exhibiting significantly high hardness and tetrahedral carbon hybridization (sp3) contents higher than 70%. Such high-quality films cannot be produced by dc arc deposition without the plasma-stabilizing mechanism presented in this study.     

A straightforward specimen holder modification for remnant magnetic-field measurement in TEM

We report a simple means to modify an analytic sample holder to perform ambient Hall probe measurements of the sample area inside a transmission electron microscope (TEM). These measurements are important in the case of electron microscopy studies involving magnetic materials. We characterize the magnetic field of the JEOL 2100F-LM, a microscope dedicated in design to perform magnetic imaging, and also of the JEOL 3000F FEG-TEM operated in Lorentz mode. In the case of the 3000F, we measure vertical remnant field about 300 Oe due to the objective lens of the microscope. In the case of the 2100F, design of the objective lens reduces the remnant field to about 4 Oe. We characterize the field along two orthogonal directions, and spatial characteristics of the field profile are made for both microscopes during all stages of specimen entry into the column. In the case of the 2100F, we additionally measure the field conditions as a function of objective lens excitation, which is important for in situ magnetization experiments. Finally, we provide experimental results illustrating the importance of these measurements.     

Ball array calibration on a coordinate measuring machine using a gage block

The distances between the balls of a ball array used in machine geometry calibration have to be very accurate. These distances can be calibrated using a laser measurement system, which requires specially designed optical devices and measuring probes. In this paper, a new and economical alternative method for calibrating the ball array is described. A single gage block is used for measuring the standard distance at the starting position. Then, the exact distances between the balls can be obtained by using the coordinate measuring machine (CMM) probe motion. This method does not depend on the accuracy of the CMM. Also, this method does not require expensive instruments or devices, but a CMM and a gage block. A simple “parallel-plane” bracket, mounted on to the measuring end of a CMM probe, is used to determine the centers of the balls automatically and accurately.     

Calculation of residual magnetic-field distributions upon hysteretic interference of a pulsed magnetic field

Russian Journal of Nondestructive Testing - Equations that are used for the calculation and distributions of the electrical voltage U(t) output from a magnetic-field transducer as it scans a...     

基于组合测量方式的新型磁场式时栅位移传感器

针对数字化精密机械加工装备和测量仪器中的关键功能部件———位移传感器测量精度过分依赖高精度加工的难题,提出基于组合测量方式的新型位移传感新方法。 利用在平面上均匀分布的激励绕组产生交变磁场,构建运动参考系,建立位移和时间基准之间的映射关系。 通过控制感应绕组的形状实现磁场精确约束,从原理上抑制谐波误差。 采用差分排布的感应绕组式及组合测量方式增强抗干扰性,提高位移测量精度。 通过电磁仿真验证,进行测量误差分析,优化结构参数。 研制了传感器样机并进行实验验证,结果表明在 144 mm 测量范围内,测量误差为±2. 25 μm,分辨力为 0. 15 μm。 不同于传统高精度位移传感器严重依赖高精度光刻制造加工,此方法通过对磁场的精确约束和传感原理创新实现精密位移测量,具有结构简单,成本低等优势具有重要学术和工程应用价值。     

电阻应变计用UV胶盖面方案浅析

现在生产电阻应变计盖面时工艺很复杂,而且固化时要上夹子会产生应力,需要一定的时日才能释放出来,新概念改用喷Uv胶的方法盖面,便于自动化大生产,不仅大大提高了生产效率,降低了成本,还可以减小盖面时应变计的内部应力,选择良好的Uv胶还可以改进盖面胶的防护性能,提高应变计的质量。     

三等量块标准装置测量不确定度的分析评定

1　引言我厂在生产中大量使用量块 ,为保证标准量值的逐级准确传递 ,建立了三等量块标准装置。该装置由三等量块、接触式干涉仪、平面平晶、温度湿度计、干涉显微镜等组成 ,可采用比较测量法检定四等及四等以下量块。设被测量块的长度实测值为Ｌ ,标称长度为ｌｓ,Ｌ与ｌｓ 之差称为量块的长度偏差 ,长度偏差的允许值范围为±ｄ。报告测量结果时 ,必须对该测量结果的质量给出定量说明 ,以确定其可信程度。测量不确定度就是对测量结果质量的定量评定参数 ,它表征可合理赋予被测量值的分散性。测量结果是否可用 ,在很大程度上取决于其不确定度…     

The detection of real defects in ferromagnetic objects using a magnetic-field imaging film

Tracer patterns of real defects during magnetic monitoring of ferromagnetic objects using a magnetic-field imaging film are presented. The results of production tests on the monitoring of a real object are demonstrated.     

Uniaxial strength asymmetry in cellular materials: An analytical model

The ability to predict failure of cellular materials depends on the knowledge of microstructural mechanisms that contribute to macroscopic behavior. In this paper, we develop microstructural models to examine the mechanisms responsible for differences in tensile and compressive strength observed in cellular materials. We limit our analyses to those materials that fail by the same mechanism (yielding or microcracking) in tension and compression. Using both a honeycomb and an open-cell foam model, we demonstrate that density-dependent, compression-strong strength asymmetry arises when two conditions are met: the cell wall material has a higher yield strength in compression than in tension, and the cell walls are loaded simultaneously by axial forces and bending moments. Our models predict that strength asymmetry (defined as the ratio of compressive to tensile yield strength of the cellular material) increases with relative density (as observed in real materials such as rigid polyurethane foams and trabecular bone), and that strength asymmetry is more pronounced in anisotropic materials (where oblique struts are more closely aligned with the direction of loading).