FRRA - Artículos en Revistashttp://hdl.handle.net/20.500.12272/35532024-03-29T09:10:38Z2024-03-29T09:10:38ZStudy of Residual Stress Relaxation Mechanics Using a Micro-indent Methodhttp://hdl.handle.net/20.500.12272/35872019-05-13T22:31:14Z2016-12-05T00:00:00ZStudy of Residual Stress Relaxation Mechanics Using a Micro-indent Method
The aim of this study is to show the feasibility and accuracy of a micro-indent method to
comprehensively evaluate the relaxation mechanics of residual stress in specimens of rolled aluminium alloy. This
micro-indent method was adapted to implement four annealing treatments. The residual displacements were
measured using a high-accuracy measuring machine, which enables to decrease the absolute error down to ±300 nm.
This study presents an innovative data analysis using Mohr's circles, which allowed to study all directions of the inplane residual stress for different relaxation times. The results revealed that the relaxation process finishes when the residual stress relief is completed in some preferential directions and then, a brief stress recovery phase begins.
2016-12-05T00:00:00ZEvaluation of Residual Stresses Induced by Face Milling Using a Method of Micro-indentshttp://hdl.handle.net/20.500.12272/35862019-05-13T22:23:50Z2017-02-17T00:00:00ZEvaluation of Residual Stresses Induced by Face Milling Using a Method of Micro-indents
The aim of this study is to determine and evaluate residual stresses induced by face milling in different
zones, which are associated with asymmetries in orientation of cutting edge. In this study, a micro-indent method is used to determine these stresses, which were induced in samples of AA 7075-T6 aluminum alloy. The residual displacements were measured, with high accuracy, using a universal measuring machine. This study includes a thorough data analysis using Mohr's circles, which enabled to assess the stress states in all in-plane directions. The results obtained in samples subjected to different combinations of process parameters showed the introduction of compressive normal components for all directions of each zone evaluated. From the high sensitivity of the microindent method used, it was possible to detect smaller differences generated between the levels reaching the stress components in the cutting zones evaluated. Furthermore, these differences were similar for all evaluated directions
when the highest feed rate was selected. This significant fact, finally, would reveal equivalent differences between
asymmetrical zones, regarding the combination of local plastic deformation and heat reaching the milled surface, for
all in-plane directions.
2017-02-17T00:00:00ZAnalysis of Residual Stresses in High Speed Milled Aluminum Alloyshttp://hdl.handle.net/20.500.12272/35852019-05-13T22:08:38Z2017-03-15T00:00:00ZAnalysis of Residual Stresses in High Speed Milled Aluminum Alloys
The purpose of this study is to evaluate, from high speed machining tests, the behavior of the residual
stresses induced in samples of AA 6082-T6 and AA 7075-T6 aluminum alloys. This study includes an exhaustive
analysis of residual stress anisotropy from diameters of Mohr's circles. The combination of process parameters was
modified in order to evaluate the stress changes introduced in different zones of the surfaces generated. A method of
micro-indents, which includes the adaptation of a universal measuring machine, was used to determine, with high
accuracy, the normal components of residual stress in several directions. The obtained results reveal that although, in
the alloy 7075-T6, the normal components are lower, in the alloy 6082-T6, these normal components tend to be
grouped into smaller intervals and also, to show a more homogeneous directional behavior when the cutting
conditions are more severe.
2017-03-15T00:00:00ZDetermination and Analysis of Residual Stresses Induced by High Speed Milling Using a Micro-indent Methodhttp://hdl.handle.net/20.500.12272/35572019-05-02T19:07:38Z2018-06-15T00:00:00ZDetermination and Analysis of Residual Stresses Induced by High Speed Milling Using a Micro-indent Method
Abstract: The purpose of this work is to determine and analyze residual stress normal components and anisotropy
degrees introduced by high-speed milling in specimens of AA 6082-T6 and AA 7075-T6 aluminum alloys. At each
machined sample, the climb and conventional cutting zones were evaluated and compared. This paper includes a
comprehensive study of thermal and mechanical effects associated with the residual stress introduction. For normal
components determination, an optimized micro-indent method was used. Each measurement sequence from this
approach was performed using a high accuracy measuring machine and classified according to thermal deviations
measured. The residual displacements were determined with an absolute error down to ±300 nm. The normal
components analysis allowed to infer the strong influence of the rolling process previous to high-speed milling and
besides, the stress levels associated with thermal effects (higher in AA 7075-T6). Finally, the lower residual stress
anisotropy degrees in both materials observed in the conventional cutting zone would indicate more homogenous
local plastic stretching in this region for all planar directions.
2018-06-15T00:00:00Z