scholarly journals Four-Point Bending Tests to Study the So-Called Plasticity Effect on the Residual Stress Results Determined by the Hole-Drilling and Ring-Core Methods

2014 ◽  
Vol 996 ◽  
pp. 319-324
Author(s):  
David von Mirbach
Keyword(s):  
Residual Stress ◽  
Bending Test ◽  
Hole Drilling ◽  
Test Machine ◽  
Bending Tests ◽  
Hole Drilling Method ◽  
Four Point Bending ◽  
Drilling Method ◽  
Four Point Bending Test ◽  
Ring Core

The hole-drilling method (HDM) and ring core method (RCM) are limited to low residual stresses under 60% of the yield stress. This issue will experimentally analyze the method of adaptive calculation function, presented by the author on the ICRS9. With a four-point-bending test machine, a defined stress can be triggered between the middle bending. In this defined loading area, the strains in two load cases with the HDM and the RCM configuration were measured. With these measured strains the residual stress calculation will be analysed.

Hole-Drilling Method for Residual Stress Measurement - Consideration of Elastic-Plastic Material Properties

2013 ◽  
Vol 768-769 ◽  
pp. 174-181 ◽  
Author(s):  
David von Mirbach
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Yield Stress ◽  
Material Properties ◽  
Plastic Material ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Elastic Plastic Material ◽  
Ring Core

Two commonly used mechanical methods for the determination of residual stresses are the hole-drilling method and the ring-core method, which can be regarded as semi-destructive. The most restricting limitation for the general applicability of both methods, according to the current state of science and technology, is the fact that the scope for relatively low residual stress under 60% of the yield stress is limited.This is a result of the notch effect of the hole or ring core, which leads to a plastification around and on the bottom of the hole and ring shaped groove already at stresses well below the yield stress of the material. The elastic evaluation of the resulting plastic strains leads consequently to an overestimation of the delineated residual stresses. In this paper the influence of elastic-plastic material properties no the specific calibration function for the hole-drilling method using the differential method is studied, and the method of adaptive calibration functions is presented.

Determination of the Necessary Geometric Parameters of the Specimen in Ring-Core Method

2013 ◽  
Vol 486 ◽  
pp. 90-95 ◽  
Author(s):  
František Menda ◽  
František Trebuňa ◽  
Patrik Šarga
Keyword(s):  
Residual Stress ◽  
Influential Factors ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Incremental Method ◽  
Core Method ◽  
Measuring Techniques ◽  
Drilling Method ◽  
Non Destructive ◽  
Ring Core

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.

Bending Test Rig for Validating the Hole Drilling Method Residual Stress Measurement

2013 ◽  
Vol 768-769 ◽  
pp. 150-157 ◽  
Author(s):  
Emilio Valentini ◽  
Alessio Benincasa ◽  
Ciro Santus
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Bending Test ◽  
Function Technique ◽  
Hole Drilling ◽  
Bending Stress ◽  
Test Rig ◽  
Stress Measurements ◽  
Hole Drilling Method ◽  
Drilling Method

This paper shows a large validation activity of the strain gage Hole Drilling Method. The residual stress measurements can not be validated easily, unless with Round Robin activity and/or comparison with other residual stress measurements such as X-ray diffraction. An accurate validation procedure is reported in the present paper, using abending test rig. The bending stress experimentally simulated a residual stress (known with uncertainty lower than 1%) that was considered as the reference stress distribution. The results showed very accurate measurement in terms of relaxed strain distributions, that were compared with the prediction obtained with the Influence Function technique. The differences were in the order of 0.5 microepsilon as standard deviation on a large number of tests. The bending stress prediction was consequently very accurate and the stress differences were as small as 1 MPa showing the accuracy potentiality of the method.

Residual Stress Prediction Using Neural Network Approach

2014 ◽  
Vol 611 ◽  
pp. 436-440 ◽  
Author(s):  
František Menda ◽  
Marcel More ◽  
G.P. Cardona-Cuervo ◽  
F.J. Martinez-Tabares
Keyword(s):  
Neural Network ◽  
Residual Stress ◽  
Hole Drilling ◽  
Neural Network Approach ◽  
Stress Evaluation ◽  
New Approach ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Stress Prediction ◽  
Ring Core

Procedures for residual stress evaluation by using Ring-Core method have not been standardized. Most common techniques are derived from the ones used for similar semi-destructive hole-drilling method. The differences between research approaches can cause significant errors. New approach using neural network is proposed as a more adaptive way for residual stress evaluation than the commonly used methods.

Residual Stress Measurements in an Autofrettage Tube Using Hole Drilling Method

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Hamid Jahed ◽  
Mohammad Reza Faritus ◽  
Zeinab Jahed
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Hoop Stress ◽  
Test Method ◽  
Test Material ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Ring Sample ◽  
Drilling Method ◽  
American Society

Relieved strains due to drilling hole in a ring sample cut from an autofrettage cylinder are measured. Measured strains are then transformed to residual stresses using calibration constants and mathematical relations of elasticity based on ASTM standard recommendations (American Society for Testing and Materials, ASTM E 837-08, 2008, “Standard Test Method for Determining Residual Stresses by the Hole-Drilling Strain-Gage Method,” American Society for Testing and Materials). The hydraulic autofrettage is pressurizing a closed-end long cylinder beyond its elastic limits and subsequently removing the pressure. In contrast to three-dimensional stress state in the autofrettage tube, the stress measurement in hole drilling method is performed on a traction free surface formed from cutting the ring sample. The process of cutting the ring sample from a long autofrettaged tube is simulated using finite element method (FEM) and the redistribution of the residual stress due to the cut is discussed. Hence, transformation of the hole drilling measurements on the ring slice to the autofrettage residual stresses is revealed. The residual stresses are also predicted by variable material properties (VMP) method (Jahed, H., and Dubey, R. N., 1997, “An Axisymmetric Method of Elastic-Plastic Analysis Capable of Predicting Residual Stress Field,” Trans. ASME J. Pressure Vessel Technol., 119, pp. 264–273) using real loading and unloading behavior of the test material. Prediction results for residual hoop stress agree very well with the measurements. However, radial stress predictions are less than measured values particularly in the middle of the ring. To remove the discrepancy in radial residual stresses, the measured residual hoop stress that shows a self-balanced distribution was taken as the basis for calculating residual radial stresses using field equations of elasticity. The obtained residual stresses were improved a lot and were in good agreement with the VMP solution.

scholarly journals Incremental Hole-Drilling Method Vs. Thin Components: A Simple Correction Approach

2014 ◽  
Vol 996 ◽  
pp. 283-288 ◽  
Author(s):  
Esther Held ◽  
Simone Schuster ◽  
Jens Gibmeier
Keyword(s):  
Residual Stress ◽  
Thin Metal ◽  
Hole Drilling ◽  
Depth Profiles ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Metal Sheets ◽  
Drilling Method ◽  
Measured Strain ◽  
The Impact

The incremental hole-drilling method is a widely used technique to determine residual stress depth profiles in technical components. Its application is limited in respect to the components geometry, for instance the components thickness. In this paper, a direct correction of the measured strain relaxations is proposed to consider the impact of deviant geometries, here the component thickness, on the residual stress evaluation that moreover, allows the application of commercially available evaluation software. The herein proposed approach is based on finite element simulation of the incremental hole drilling. The simulated strain relaxations for thin metal sheets are evaluated with an algorithm as used in commercially available evaluation software (i) for uncorrected data as well as (ii) for strain data corrected by the proposed correction procedure. It is shown that the correction approach leads to a significant improvement of the measurement accuracy. Further, by means of the approach residual stress depth profiles in thin metal sheets can be as usual determined using commercial evaluation software for the incremental hole-drilling method regardless of the algorithm used, i.e. differential or integral.

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