Papers by Keyword: Calibration Coefficient

Abstract: The incremental hole-drilling method was adapted for the measurement of residual stresses in polymer based composite materials. The parameters of the hole drilling process and the strain measurement in non-reinforced and 70 weight-percent glass-fiber-reinforced polypropylene were investigated. Calibration coefficients for the calculation of the residual stresses in the orthotropic material systems were determined by Finite Element Analysis. By means of application of the method to unidirectional and cross-ply glass-fiber reinforced composites the residual stresses, maximum measurable depths and measurement uncertainties could be derived.

Abstract: The evaluation of residual stresses using Ring-Core method requires complex analysis of the acquired strain values. The development is based on ASTM Standard E837-08 for hole-drilling method, but the specific approach for Ring-Core is needed. The input data sets obtained from strain gage rosette are categorized by proposed uniformity test. The influence of geometric parameters of the specimen on this test and subsequently on the both uniform and nonuniform calculations is considered.

Abstract: There are several measuring techniques for determining residual stress which can be divided according to the created damage in to the construction in non-destructive, semi-destructive and destructive ones. One of the most common is semi-destructive hole-drilling method. This paper deals about Ring-Core method which is based on the similar principles. Today, there is no standard for the Ring-Core method, thus it is important to consider various influential factors. One of them are the dimensions of specimen. Calibration coefficients are determined by finite element (FE) analysis using the commercial software Solidworks. These coefficients are used for residual stress evaluation by incremental method used in Ring-Core method. The influence of different specimen dimensions on the accuracy of the evaluated residual stresses is considered.

Abstract: The safety and load-bearing capacity of an in-service urban reinforced concrete slant leg rigid frame bridge over railway is assessed by field testing and finite element analysis. The bridge is located in Qitaihe city, the northeastern of China. The two heavy trucks and three different loading test configurations are used in experiment. The three load figuration is set up and performed based on the result of technical condition investigation and finite element numerical analysis. The vertical displacement and key section strain response are recorded during experiment. Loading-bearing capacity and safety performance of the bridge is analyzed and evaluated according to measured data combining with numerical analysis. The testing result shows that structural stiffness and strength of the bridge do not satisfy the requirements of the original design. Based on the assessment result, some proposals are proposed to the management office. A moderate maintenance and reinforcement treatment should be carried out for this bridge to improve the bearing capacity and ensure safety operation. Before that completed some traffic control measures should be taken to avoid aggravating diseases and damages of the bridge due to passing heavy vehicle.

Abstract: Hole drilling strain gage method is a semi-destructive measurement. The method is most commonly used to measure residual stresses. The relieved strains are measured around the drilled hole, and the residual stresses are estimated by the mechanical relationship between relieved strains and residual stresses as well calibration coefficients. The calibration coefficients indicate the relieved strains due to unit stresses within the hole depth. Finite element method is always used to determine the calibration coefficients, and the analytical model is based on the infinite plate. But the geometrical shape and size of cylindrical part are different from the infinite plate. The relieved strains around the drilled hole are different too. Finite element model of the cylindrical part is constructed to obtain the hole drilling calibration coefficients. The measurement of residual stresses in a cylindrical part subject to axial loading calculated by calibration coefficients of both infinite plate and cylindrical part model are compared to show the difference.

Abstract: non-contact measurement of shaft component realizes dynamic measuring ,which bases on image measurement technology.After the image of shaft is obtained,Sobel operator is used for preliminary locating to image edge,on basis of this ,discrete points of image edge are fitted by least square method for achieving edge subpixel location.By precision analysis, size solution method is acquired when the error is minimum;After calibration coefficient k is gained, the part size is correctly calculated. By experiment, it shows that measurement precision is improved effectively and measurement error is less than ±20μm when resolution of CCD camera is 1392×1040 and its pixel size is 4.65μm.

Abstract: This article describes the time difference ultrasonic flow meter measurement principle, by analyzing the ultrasonic flow meter test results, using the theory of Newton interpolation correction calibration constants, solves the problems that the measurement results will suddenly appear more random beating and further improve measurement accuracy of the ultrasonic flow meter.

Abstract: For measuring in-depth residual stress in 3D cylinder structure easily in this paper, the semi-destructive incremental hole drilling technique combined with finite element method is used, the calibration coefficients of 3D cylinder components are calculated, and the relationship between strain and stress is determined, the changes of calibration coefficients are analysed, the residual stress of one steering joint of automobile is measured, and the errors of residual stress are discussed.