Search results for "RESIDUAL STRESS"
showing 10 items of 119 documents
Residual Stresses and Reactivity of Solids. Determination and Part Plaid in the Reaction Mechanisms
1996
Dependence between aging treatments and residual stresses on composite laminate
2006
International audience; The objective of this paper is to study the influence of residual stresses due to fabrication conditions on the thermomechanical behavior of carbon/epoxy laminate structures (cross ply). These studied laminates have undergone various cycles of thermal aging. The addition of a post-cure cycle after the end of the initial cycle makes it possible to reduce the residual stresses level. The incremental hole-drilling method is used to measure the residual strain in the laminates. These measured strains and the numerical calibration coefficients obtained by the finite element method allow to calculating the residual stress distribution in composite depth. The obtained resul…
Optimization of depth increment distribution in the ring-core method
1996
The integral equation method is the most suitable calculation procedure for the determination of non-uniform residual stresses by semi-destructive mechanical methods such as hole and ring-core drilling. However, the high sensitivity to strain measurement errors due to the ill-conditioning of the equation sets has prevented its practical use. Examination of the influence of the strain measurement error on the calculated stresses and its propagation has shown that, for given maximum groove depth and total steps number, the error sensitivity depends on the particular depth increment distribution used. By means of an alternative matrix formulation of the equation sets the depth increment distr…
On the Measurement and Prediction of the Out-of-Plane Displacement Surrounding Cold-Expanded Holes
2010
Experimental measurements of the out-of-plane displacement surrounding cold-expanded holes in a 6082-T6 aluminum alloy were made with a 3D optical scanner using the technique of the encoded light-pattern projection in white light. The measured surface profiles have shown the thickness discontinuity along the hole edge due to the effect of the split in the sleeve. An analytical–numerical solution of the out-of-plane displacement is presented based on existing analytical models. Thus, the results given by the analytical model were then compared with the experimental data and with a finite element (FE) model that simulates the cold-expansion process. The location of the elastic–plastic boundar…
MAPPING MULTIPLE RESIDUAL STRESS COMPONENTS USING THE CONTOUR METHOD AND SUPERPOSITION
2008
The standard contour method determines the residual stress component normal to the plane of measurement. This talk presents extensions to the contour method to allow determination of multiple stress components. Two extensions are presented, both using additional stress measurements and then superposition to determine the original residual stresses. The first extension involves making additional cuts to determine stresses on multiple cut planes, using only the contour method. The second extension involves measuring in-plane stresses on the surface exposed by the original cut, using x-ray diffraction and hole drilling in this case. Experiments were preformed on indented disks of both 316L sta…
ERROR AND UNCERTAINTY ANALYSIS OF RESIDUAL STRESS EVALUATION BY USINGTHE RING-CORE METHOD
2014
The Ring-Core Method is a technique used for the experimental analysis of the residual stresses in mechanical components. For uniform and non-uniform residual stresses estimation, the use of the method leads in general to accurate results but, unfortunately at present the user does not have appropriate procedures to correct the obtained results from systematic errors as well as to estimate the uncertainty due to random errors. In order to overcome such drawbacks, in the present work, the procedures for the correction of the effects of the main error sources and for the stress uncertainty estimation, are proposed. The practical application of such procedures allow the user to highlight the r…
Automatic photoelastic methods for the analysis of Membrane residual stresses in glass
2014
IL METODO DI PROVA “AIAS - TR” PER LA MISURA DELLE TENSIONI RESIDUE COSTANTI O VARIABILI CON LA TECNICA DEL FORO INCREMENTALE
2010
Viene presentata una sintesi dell’attività svolta dal Gruppo di lavoro AIAS “Tensioni Residue” nel periodo dal 2006 al 2009. Lo scopo dell’attività è stata l’elaborazione del metodo AIAS - TR 01 per la misura delle tensioni residue con il metodo del foro incrementale. La normativa tecnica esistente sull’argomento (ASTM E 837-08) [1] ha un campo di applicabilità ristretto; infatti essa non considera alcuni effetti che possono influenzare l’accuratezza della misura. Il metodo di prova (AIAS - TR 01) fornisce una visione d’insieme del metodo della rosetta forata, aggiornata all’attuale stato dell’arte (2009) sia a livello tecnologico che a livello teorico. Le principali innovazioni riguardano …
ERROR AND UNCERTAINTY ANALYSIS OF THE RESIDUAL STRESSES COMPUTED BY USING THE HOLE DRILLING METHOD
2011
The hole-drilling method is one of the most used techniques for the experimental analysis of the residual stresses in mechanical components. For both through-thickness uniform and non-uniform residual stresses, its practical application is standardised by the ASTM E837-08. For uniform residual stresses, to which the present work deals with, the use of the method in accordance with the ASTM limitations, leads to results with a bias of about 10%. Unfortunately, although some experimental parameters can be frequently out of the corresponding standard limitation, the user does not have appropriate procedures to correct the obtained results which, in accordance with the ASTM standard, have to be…
Experimental and Numerical Analysis of the Distribution of Residual Stresses Induced by Laser Shock Peening in a 2050-T8 Aluminium Alloy
2011
Laser shock peening (LSP) is an innovative surface treatment technique successfully applied to improving fatigue performance of metallic material. The specific characteristic of (LSP) is the generation of a low work-hardening and a deep compressive residual stresses mechanically produced by a laser-induced shock wave propagating in the material. The aim of this study is to analyse the residual stress distribution induced by laser peening in 2050-T8 aluminium alloy experimentally by the X-ray diffraction technique (method sin2Y) and numerically, by a finite element numerical modelling. A specific focus was put on the residual stress distribution along the surface of the impacted material.