Experimental investigations on thermo mechanical behaviour of aluminium alloys subjected to tensile loading and laser irradiation

2017 ◽  
Author(s):  
Mohsan Jelani ◽  
Zewen Li ◽  
Zhonghua Shen ◽  
Maryam Sardar ◽  
Aasma Tabassum
Keyword(s):  
Laser Irradiation ◽  
Mechanical Behaviour ◽  
Aluminium Alloys ◽  
Tensile Loading ◽  
Experimental Investigations

Mechanical Behaviour in the Mushy State during Isothermal Tensile Testing

2006 ◽  
Vol 519-521 ◽  
pp. 1877-1882 ◽  
Author(s):  
Damien Fabrègue ◽  
Alexis Deschamps ◽  
Michel Suéry ◽  
Warren J. Poole
Keyword(s):  
Solid Fraction ◽  
Mechanical Behaviour ◽  
Aluminium Alloys ◽  
Fracture Stress ◽  
Maximum Stress ◽  
Hot Tearing ◽  
Brittle Ductile Transition ◽  
Partial Remelting ◽  
Maximal Stress ◽  
The Difference

In order to improve the understanding of hot tearing during laser welding of aluminium alloys, the rheology of the alloys in the mushy state must be characterized. The present work investigates the mechanical behaviour of the aerospace alloy AA6056 using a specially designed isothermal tensile test in the mushy state. Using a Gleeble thermo-mechanical machine, two different tests have been performed: i) tests during partial remelting and ii) tests after partial solidification at a high cooling rate. These tests have been carried out not only on the 6056 alloy but also on a mix between 6056 and 4047 Al-Si alloy which corresponds to the composition of the nugget of a laser using a filler wire. The increase of the solid fraction results in an increase of the maximum stress and a change on the fracture surface from a smooth dendritic to a more ductile one. Moreover, the alloys exhibit a typical visco plastic behaviour with an increase of the maximal stress with the strain rate. When the test is performed at a particular solid fraction of 0.97, the fracture is more erratic and the ductility is low. The results show the existence of a ductile/brittle/ductile transition with the fraction of solid. The fracture stress is shown to be higher when testing after partial remelting as compared to partial solidification for the same solid fraction. This is due to the difference in microstructure of the mushy zone and more particularly in the connectivity of the solid skeleton. An adapted creep law is used to describe the mechanical behaviour of alloys during the partial remelting test using the fraction of grain boundary wetted by the liquid given by Wray. This law is shown to be irrelevant to the partial solidification tests, as a result of the modified geometry of the liquid phase. From these tests, we have determined a new law relating the solid fraction to the fraction of grain boundaries wetted by the liquid. This law is a useful tool to predict the mechanical behaviour when mechanical loading occurs during solidification.

Laser-Induced Deformation Patterns in Thin Films and Surfaces

1999 ◽  
Vol 121 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Daniel Walgraef
Keyword(s):  
Thin Films ◽  
Laser Irradiation ◽  
Surface Deformation ◽  
Laser Intensity ◽  
Laser Beams ◽  
Experimental Investigations ◽  
Relative Importance ◽  
Periodic Patterns ◽  
One Dimensional ◽  
Deformation Patterns

The coupling between surface deformation and defect motion may be at the origin of deformation patterns in thin films under laser irradiation. We analyze the dynamics of laser-induced vacancy densities and deformation fields and show how it triggers deformational instabilities, in the case of uniform and focused laser irradiation. Pattern selection analysis is performed, through linear, nonlinear, and numerical methods. In irradiation with extended beams, we show that, according to the relative importance of nonlinearities arising from the defect or from the bending dynamics, square, hexagonal or even quasi-periodic patterns are selected. It appears, furthermore, that one-dimensional gratings are always unstable in isotropic systems. In irradiation with focused laser beams, rose deformation patterns, with petal number increasing with laser intensity, naturally arise in this model, in qualitative agreement with experimental observations. These results claim for more systematic and quantitative experimental investigations of deformational pattern formation under laser irradiation.

scholarly journals Effect of Length of False Banana Fibre (Ensete ventricosum) on Mechanical Behaviour under Tensile Loading

2016 ◽  
Vol 47 (2) ◽  
pp. 90-96 ◽  
Author(s):  
Č. Mizera ◽  
D. Herák ◽  
P. Hrabě ◽  
M. Müller ◽  
A. Kabutey
Keyword(s):  
Tensile Strength ◽  
Theoretical Model ◽  
Mathematical Models ◽  
Mechanical Behaviour ◽  
Modulus Of Elasticity ◽  
Tensile Loading ◽  
Gauge Length ◽  
Ensete Ventricosum ◽  
Banana Fibre ◽  
Volume Energy

Abstract The effect of gauge length of false banana fibre (Ensete ventricosum) on the tensile strength, volume energy, and modulus of elasticity under tensile loading was examined. Fibres of gauge length L0 (mm) 10, 20, 40, 80, 160, and 320 mm were prepared and tested until rupture point at strain rate of 0.05 min−1. Mathematical models describing the mechanical behaviour of the varying gauge lengths were presented. With the increasing gauge length of fibre, the tensile strength and volume energy decreased while the values of modulus of elasticity increased. The theoretical model describing the mechanical behaviour of Ensete fibre under tensile loading presented herein provides useful information for the fibres application in industry. The determined models could be used as a background for further research focused on Ensete fibre application.

Sign in / Sign up

Export Citation Format

Share Document