A study of residual stress distribution through the thickness of p/sup +/ silicon films (thermal oxidation effects)

1993 ◽  
Vol 40 (7) ◽  
pp. 1245-1250 ◽  
Author(s):  
W.-H. Chu ◽  
M. Mehregany
1991 ◽  
Vol 239 ◽  
Author(s):  
W. H. Chu ◽  
M. Mehregany ◽  
X. Ning ◽  
P. Pirouz

AbstractThis paper presents results from measurements of residual stress-induced bending moment of heavily-boron-doped (p+) silicon films. Microfabricated free-standing cantilever beams of p+ silicon were fabricated by using anisotropie etching of (100) silicon wafers in ethylene-diamine and pyrocatechol. The p+ etch stops forming the cantilevers were created by diffusion from a solid source at 1125°C for one and two hour time durations. The nonuniform residual stress distribution through the thickness of the p+ silicon cantilevers resulted in a deflection of the beams. The as-diffused p+ silicon films had a residual stress distribution through the film thickness which resulted in negative bending moments. Thermal oxidation subsequent to the diffusion step modified the residual stresses near the top surface or, perhaps, plastically deformed the near surface region of the p+ thin film. As a result, thermally oxidized p+ silicon films exhibited a positive bending moment. Measurements of the deflection curves of the beams in conjunction with beam theory were used to calculate the residual stress-induced bending moments.


2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results


Author(s):  
A.G. Ramu ◽  
Sunwoo Kim ◽  
Heungwoo Jeon ◽  
Amal M. Al-Mohaimeed ◽  
Wedad A. Al-onazi ◽  
...  

Author(s):  
René Selbmann ◽  
Markus Baumann ◽  
Mateus Dobecki ◽  
Markus Bergmann ◽  
Verena Kräusel ◽  
...  

AbstractThe residual stress distribution in extruded components and wires after a conventional forming process is frequently unfavourable for subsequent processes, such as bending operations. High tensile residual stresses typically occur near the surface of the wire and thus limit further processability of the material. Additional heat treatment operations or shot peening are often inserted to influence the residual stress distribution in the material after conventional manufacturing. This is time and energy consuming. The research presented in this paper contains an approach to influence the residual stress distribution by modifying the forming process for wire-like applications. The aim of this process is to lower the resulting tensile stress levels near the surface or even to generate compressive stresses. To achieve these residual compressive stresses, special forming elements are integrated in the dies. These modifications in the forming zone have a significant influence on process properties, such as degree of deformation and deformation direction, but typically have no influence on the diameter of the product geometry. In the present paper, the theoretical approach is described, as well as the model set-up, the FE-simulation and the results of the experimental tests. The characterization of the residual stress states in the specimen was carried out by X-ray diffraction using the sin2Ψ method.


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