Numerical simulation of surface deformation and residual stresses fields in laser shock processing experiments

Morales

Porro

et al. 2010

MSF

Self Cite

Láser shock processing (LSP) is consolidating as an effective technology for the improvement of metallic materials surface properties involving their fatigue life. The main acknowledged advantage of the LSP technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly the life improvement of the treated specimens against wear, crack growth and stress corrosión cracking. Progress accomplished by the authors in the line of practical development of the LSP technique at an experimental level, aiming its integral assessment from an interrelated theoretical and experimental point of view, is presented in this paper. Concretely, experimental results on the residual stress profiles and associated surface properties modification successfully reached in typical materials (especially Al and Ti alloys) under different LSP irradiation conditions are presented, a correlated analysis of the residual stress profiles obtained under different irradiation strategies and the evaluation of the corresponding induced surface properties as roughness and wear resistance being also presented. Through a coupled theoretical-experimental analysis the real possibilities of the LSP technique as a possible substitutive of related traditional surface modification techniques as, for example, shot peening.

Section: Introductionmentioning

confidence: 99%

Induction of Engineered Residual Stresses Fields and Associate Surface Properties Modification by Short Pulse Laser Shock Processing

Morales

Porro

et al. 2010

MSF

Self Cite

“…The authors have developed a calculational system to study laser shock microforming [5][6][7]. It consists of two principal modules conceived for the analysis of plasma evolution (shock waves generation) and induced residual stresses (shock wave evolution and material plastic deformation) under two different but complementary approaches [7].…”

Section: Physics Of Laser Shock Microforming Numerical Modelingmentioning

confidence: 99%

“…It consists of two principal modules conceived for the analysis of plasma evolution (shock waves generation) and induced residual stresses (shock wave evolution and material plastic deformation) under two different but complementary approaches [7]. Provided that the effects to be analyzed are strongly non linear as a conference of the leading role of material plastic deformations, the influence of the different process parameters (laser energy and laser spot position) on net bending angle have been studied with the developed numerical model.…”

Section: Physics Of Laser Shock Microforming Numerical Modelingmentioning

confidence: 99%

Laser shock microforming of thin metal sheets

Applied Surface Science

Morales

García–Ballesteros

et al. 2009

Self Cite

Keywords: Laser microforming Forming mechanisms Numerical modeling Experimental validationContinuous and long-pulse lasers have been used for the forming of metal sheets in macroscopic mechanical applications. However, for the manufacturing of micro-electromechanical systems (MEMS), the applicability of such type of lasers is limited by the long-relaxation-time of the thermal fields responsible for the forming phenomena. As a consequence of such slow relaxation, the final sheet deformation state is attained only after a certain time, what makes the generated internal residual stress fields more dependent on ambient conditions and might make difficult the subsequent assembly process from the point of view of residual stresses due to adjustment.The use of ns laser pulses provides a suitable parameter matching for the laser forming of an important range of sheet components used in MEMS that, preserving the short interaction time scale required for the predominantly mechanic (shock) induction of deformation residual stresses, allows for the successful processing of components in a medium range of miniaturization, particularly important according to its frequent use in such systems.In the present paper, a discussion is presented on the physics of laser shock microforming and the influence of the different effects on the net bending angle. The experimental setup used for the experiments, sample fabrication and experimental results of influence of number of laser pulses on the net bending angle are also presented.

“…A similar kind of problems has been analized for the case of Shot Peening by Guagliano [5] With the aid of the calculational system developed by the authors (SHOCKLAS®; see [6][7]), the analysis of the problem of LSP treatment for induction of residual stress fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration has been envisaged. Numerical results directly tested against experimental results have been obtained confirming the critical influence of the laser energy and irradiation geometry parameters.…”

Section: Introductionmentioning

confidence: 99%

Induction of through-thickness compressive residual stress fields in thin Al2024-T351 plates by laser shock processing

International Journal of Structural Integrity

Correa

Porro

et al. 2015

Laser Shock Processing (LSP) has been demonstrated as an emerging technique for the induction of RS's fields in sub-surface layers of relatively thick specimens. However, the LSP treatment of relatively thin specimens brings, as an additional consequence, the possible bending in a process of laser shock forming. This effect poses a new class of problems regarding the attainment of specified RS's depth profiles in the mentioned type of sheets, and, what can be more critical, an overall deformation of the treated component.The analysis of the problem of LSP treatment for induction of tentatively throughthickness RS's fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration is envisaged in this paper.The coupled theoretical-experimental predictive approach developed by the authors has been applied to the specification of LSP treatments for achievement of RS's fields tentatively able to retard crack propagation on normalized specimens. A convergence between numerical code results and experimental results coming from direct RS's measurement is presented as a first step for the treatment of the normalized specimens under optimized conditions and verification of the crack retardation properties virtually induced.