Flexural motion due to laser ablation: Influence of force location on the flexural motion

2004 ◽  
Vol 218 (12) ◽  
pp. 1411-1420 ◽  
Author(s):  
B S Yilbas ◽  
J Hyder
Keyword(s):  
Shear Stress ◽  
Laser Ablation ◽  
Maximum Shear Stress ◽  
Substrate Material ◽  
Thin Layers ◽  
Stress Fields ◽  
Pressure Force ◽  
Ablation Process ◽  
Maximum Displacement ◽  
Recoil Pressure

The flexural motion of a multilayer assembly subjected to laser ablation is studied. The assembly consists of thin layers of Inconel alloy (top and bottom layers) and a steel layer (intermediate layer). The assembly resembles a stainless steel sheet with both surfaces coated. The recoil pressure generated during the ablation process results in a loading pressure force acting normal to the assembly surface. The pressure force causes flexural motion in the assembly. In order to secure a sufficiently large flexural displacement, a cantilever arrangement of the assembly is considered. The recoil pressure and the resulting force are formulated and the flexural displacement as well as the resulting stress fields are computed. The influence of the pressure force location at the assembly surface on the flexural motion is examined. It is found that the time occurrence of maximum flexural displacement is the same for all the load locations and the maximum displacement occurs at the free end of the cantilever assembly. The magnitude of normal stresses and shear stress is less than the yielding limit of the substrate material. Moreover, the maximum shear stress is almost three times the maximum normal stress in the assembly.

Influence of layers on flexural motion of a multilayer assembly due to the laser ablation process

2003 ◽  
Vol 217 (8) ◽  
pp. 945-954 ◽  
Author(s):  
B S Yilbas ◽  
J Hyder
Keyword(s):  
Equivalent Stress ◽  
Substrate Material ◽  
Liquid Interface ◽  
Flexural Wave ◽  
Maximum Magnitude ◽  
Pressure Loading ◽  
Maximum Displacement ◽  
Recoil Pressure ◽  
Laser Ablation Process ◽  
Maximum Equivalent Stress

Laser-induced evaporation results in recoil pressure at the vapour-liquid interface, which in turn gives rise to flexural wave generation in the substrate material due to impact pressure loading at the interface. In the present study, recoil pressure due to laser non-conduction limited heating is formulated and because of pressure loading at the vapour-liquid interface the flexural motion of the substrate material is modelled. A multilayer cantilever arrangement of the workpiece, consisting of layers of steel and Inconel alloy, is considered. In order to investigate the influence of the number of layers on the resulting flexural motion and stress fields, four cases and three layer arrangements are taken into account. It is found that the maximum displacement in the order of 10-4m occurs while the maximum equivalent stress is about 20 MPa. The maximum magnitude of shear stress is higher than that of equivalent stress.

Modeling of Cut Depth and Surface Analyses of Silicon Wafer in Laser Micromachining Process

2016 ◽  
Vol 835 ◽  
pp. 242-247
Author(s):  
Seksit Mekloy ◽  
Viboon Tangwarodomnukun ◽  
Chaiya Dumkum
Keyword(s):  
Laser Ablation ◽  
Surface Morphology ◽  
Laser Power ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Surface Characteristics ◽  
Substrate Material ◽  
Ablation Process ◽  
Laser Ablation Process ◽  
Cut Depth

Silicon has widely been used as a substrate material in various microfabrication processes. Cut depth and surface morphology of silicon obtained from laser ablation process have to be well controlled to achieve the required features of micro-components being made. Though laser power has been known as a major factor affecting these responses, the detailed investigations of this factor on cut geometries and surface quality have still been deficiency. In this research, the cut geometries and surface characteristics of silicon induced by a pulse laser were experimentally investigated. The increase in laser power not only increased the cut dimensions, but also increased the debris deposition on and inside the cut channel. Furthermore, an analytical model was developed in this study to predict the cut depth of silicon in pulsed laser ablation, and an agreement between the prediction and experiment was also demonstrated.

scholarly journals Parametric Study of the Borehole Drilling in Jointed Rock Mass

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yanan Gao ◽  
Yudong Zhang ◽  
Zetian Zhang ◽  
Minghui Li ◽  
Yingfeng Sun ◽  
...  
Keyword(s):  
Shear Stress ◽  
Rock Mass ◽  
Coal Seam ◽  
Coal Mining ◽  
Joint Angle ◽  
Maximum Shear Stress ◽  
Element Model ◽  
Von Mises Stress ◽  
Maximum Displacement ◽  
Von Mises

Gas is associated with coal mining; it commonly exists in the coal seam. It is one of the major dangers during the production because its reaction between the coal masses may induce the gas-coal outburst as well as it being an expositive matter. The gas accident has caused a huge amount of property damage and casualties. Therefore, the primary precaution for coal mining is gas control. At present, drilling and extraction are the main approaches for gas accident prevention. After drilling, the ground pressure will be released; the gas which is in a free state or absorbed in the coal seam will be easy to extract as the migration channel is enhanced. Hence, one of the most concerned problems is the stress redistribution of the coal and rock mass around the borehole. In practical engineering, there are many joints distributed in the coal and rock strata, so it is necessary to investigate the effect of the drilling in the jointed coal and rock mass. In this paper, the boundary element model of the borehole in the jointed coal and rock mass is established to study the influence of joints on the stress and displacement field. The following results can be obtained. The number of joints has a significant effect on the maximum displacement of the coal and rock mass. The maximum displacement increases with the number of the joint. The position of the maximum displacement shifts from the boundary of the borehole to the far field. Meanwhile, it can be found that the displacement may reach a peak value when the joint angle is 30° and if the joint number is less than 4, and the maximum displacement may occur under the joint angle of 45° and if the joints number continuous increases. The von Mises stress has a trend of increasing with the number of joints when the joint angle is less than 30°, while it has a decreasing trend when the joint angle is larger than 30°. The max stress may occur at the joint angle of 15°. The maximum shear stress occurs mostly in the No. 4 joint and the No.7 joint. When the joint angle is 30°, the maximum shear stress occurs in the No. 3 joint and the No. 4 joint. The overlap of the position of the maximum von Mises stress or the maximum displacement with different joint angles or different numbers of joint leads to a reexploration of such positions. The position of the maximum von Mises stress and the maximum displacement o is relatively steady, which locates symmetrically around the borehole. The line between the points that behaves as the maximum von stress is approximately perpendicular to the joint direction.

Asymptotic Stress Fields for Stationary Cracks Along the Gradient in Functionally Graded Materials

2002 ◽  
Vol 69 (3) ◽  
pp. 240-243 ◽  
Author(s):  
V. Parameswaran ◽  
A. Shukla
Keyword(s):  
Shear Stress ◽  
Stress Field ◽  
Functionally Graded Materials ◽  
Maximum Shear Stress ◽  
Functionally Graded ◽  
Stress Fields ◽  
Shear Mode ◽  
Graded Materials ◽  
Opening Mode ◽  
Constant Maximum

Stress field for stationary cracks, aligned along the gradient, in functionally graded materials is obtained through an asymptotic analysis coupled with Westergaard’s stress function approach. The first six terms of the stress field are obtained for both opening mode and shear mode loading. It is observed that the structure of the terms other than r−1/2 and r0 are influenced by the nonhomogeneity. Using this stress field, contours of constant maximum shear stress are generated and the effect of nonhomogeneity on these contours is discussed.

The Stress Field Generated in an Elastic Layer by Normally Loaded, Periodically Spaced Circular Contacts

1974 ◽  
Vol 96 (3) ◽  
pp. 376-380 ◽  
Author(s):  
T. G. Johns
Keyword(s):  
Shear Stress ◽  
Stress Field ◽  
Layer Thickness ◽  
Elastic Layer ◽  
Substrate Material ◽  
Contact Spot ◽  
Thin Layers ◽  
State Of Stress ◽  
Octahedral Shear Stress ◽  
Contact Surfaces

The stress field generated in an elastic layer by normally loaded, periodically spaced circular contacts is analyzed. It is intended that this model represent a pair of rough, plated contact surfaces whose plating is much more compliant than the substrate material. The effect of plating thickness and spacing of load-bearing asperities upon the state of stress within the layer is studied. It is shown that there exist values of layer thickness and contact-spot spacing such that the octahedral shear stress within the layer is maximized. Further, for very thin layers, the maximum octahedral shear occurs at the surface of the layer as in tangentially loaded contacts.

Detection and Characterization of an Electrical Failure Induced during Laser Ablation of Packages

2008 ◽  
Author(s):  
P. Schwindenhammer ◽  
H. Murray ◽  
P. Descamps ◽  
P. Poirier
Keyword(s):  
Laser Ablation ◽  
Integrated Circuits ◽  
Failure Analysis ◽  
Ablation Process ◽  
Thermally Induced ◽  
Electrical Failure ◽  
Electrical Phenomenon ◽  
Semiconductor Packages ◽  
Complex Semiconductor

Abstract Decapsulation of complex semiconductor packages for failure analysis is enhanced by laser ablation. If lasers are potentially dangerous for Integrated Circuits (IC) surface they also generate a thermal elevation of the package during the ablation process. During measurement of this temperature it was observed another and unexpected electrical phenomenon in the IC induced by laser. It is demonstrated that this new phenomenon is not thermally induced and occurs under certain ablation conditions.

scholarly journals Studying the performance of fully encapsulated rock bolts with modified structural elements

2021 ◽  
Author(s):  
Jianhang Chen ◽  
Hongbao Zhao ◽  
Fulian He ◽  
Junwen Zhang ◽  
Kangming Tao
Keyword(s):  
Shear Stress ◽  
Load Transfer ◽  
Maximum Shear Stress ◽  
Coupling Model ◽  
Numerical Approach ◽  
Rock Bolt ◽  
Structural Elements ◽  
Rock Bolts ◽  
Two Stage ◽  
Bolt Diameter

AbstractNumerical simulation is a useful tool in investigating the loading performance of rock bolts. The cable structural elements (cableSELs) in FLAC3D are commonly adopted to simulate rock bolts to solve geotechnical issues. In this study, the bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model. Furthermore, the FISH language was used to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. Comparison was performed between numerical and experimental results to confirm that the numerical approach can properly simulate the loading performance of rock bolts. Based on the modified cableSELs, the influence of the bolt diameter on the performance of rock bolts and the shear stress propagation along the interface between the bolt and the grout were studied. The simulation results indicated that the load transfer capacity of rock bolts rose with the rock bolt diameter apparently. With the bolt diameter increasing, the performance of the rock bolting system was likely to change from the ductile behaviour to the brittle behaviour. Moreover, after the rock bolt was loaded, the position where the maximum shear stress occurred was variable. Specifically, with the continuous loading, it shifted from the rock bolt loaded end to the other end.

Comparison of the laser ablation process on Zn and Ti using pulsed digital holographic interferometry

2010 ◽  
Vol 256 (14) ◽  
pp. 4633-4641 ◽  
Author(s):  
E. Amer ◽  
P. Gren ◽  
A.F.H. Kaplan ◽  
M. Sjödahl ◽  
M. El Shaer
Keyword(s):  
Laser Ablation ◽  
Holographic Interferometry ◽  
Ablation Process ◽  
Laser Ablation Process
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