Development of a focusing micromirror device with an in-plane stress relief structure in SOI technology

2013 ◽  
Author(s):  
Wolfgang Kronast ◽  
Ulrich Mescheder ◽  
Bernhard Müller ◽  
Rolf Huster
Keyword(s):  
Plane Stress ◽  
Stress Relief ◽  
Relief Structure ◽  
Soi Technology

Evaluation new corner stress relief structure layout for high robust metallization

2014 ◽  
Vol 54 (9-10) ◽  
pp. 1977-1981
Author(s):  
V. Hein ◽  
J. Kludt ◽  
K. Weide-Zaage
Keyword(s):  
Stress Relief ◽  
Relief Structure ◽  
Structure Layout

The mechanics of a pop-up: a stress relief phenomenon

1995 ◽  
Vol 32 (2) ◽  
pp. 368-373 ◽  
Author(s):  
John Roorda
Keyword(s):  
Relative Motion ◽  
Plane Stress ◽  
Stress Relief ◽  
Critical Value ◽  
Near Surface ◽  
Symmetric Deformation ◽  
Frictional Forces ◽  
Horizontal Substrate ◽  
Rock Strata

The mechanical behaviour of a "pop-up" in a layered, near-surface rock formation under compression is examined by treating it as a one-way buckling problem in which a compressed flat plate lying on a horizontal substrate can suddenly buckle upward. Axi-symmetric deformation is assumed, the plate has self-weight, and frictional forces resist relative motion between the supporting substrate and the plate. It is found that, given a small initial disturbance, the plate may bulge upward in an explosive manner provided the in situ compressive in-plane stress exceeds a critical value. This phenomenon, which frequently happens in quarrying operations, acts as a stress relief mechanism that affects not only the localized buckle but also a large radial area surrounding the pop-up as inward slippage occurs. A numerical example of the upheaval of a limestone plate is presented. Key words : pop-up, buckle, rock strata, stress relief.

Effect of State-of-Stress and Yield Criterion on the Bauschinger Effect

1968 ◽  
Vol 90 (3) ◽  
pp. 403-408 ◽  
Author(s):  
S. T. Rolfe ◽  
R. P. Haak ◽  
J. H. Gross
Keyword(s):  
Yield Strength ◽  
Plane Strain ◽  
Plane Stress ◽  
Bauschinger Effect ◽  
Yield Criterion ◽  
Cold Deformation ◽  
Stress Relief ◽  
Cold Forming ◽  
State Of Stress ◽  
Direction Opposite

During fabrication, the cold forming of structural components may reduce the yield strength of a component if it is loaded in a direction opposite to that of the cold forming. This reduction in yield strength, referred to as the Bauschinger effect, is influenced by the state-of-stress under which the cold forming is performed, by the criterion used to determine the yield strength, and by the use of post-forming stress relief. To establish the importance and magnitude of these effects, specimens from 2 1/2-in-thick plates of HY-80 steel, cold-formed by plane strain bending, were tested along with specimens that were cold-formed by plane-stress axial straining. For material tested in a direction opposite to that of cold forming, the Bauschinger effect was observed both in tension and compression, whereas for material tested at 90 deg to the direction of cold forming in plane strain, both the tensile and compressive yield strengths increased and no Bauschinger effect was observed. Because of the difference in restraint, the Bauschinger effect was greater for plane-stress axial deformation than for plane-strain bending deformation. The Bauschinger effect was greater when the yield strength was determined at small offsets and was essentially eliminated at an offset greater than 0.5 percent. In addition, the Bauschinger effect was greatest for small amounts of cold deformation and was progressively decreased by strain hardening at large amounts of cold deformation. The reduction in secant modulus and in yield strength (Bauschinger effect) in cold-formed material was essentially eliminated by stress-relief treatment at 1025 deg. F. The results indicate the importance of knowing the cold-forming state-of-stress, the criterion used in determining yield strength, and the effects of stress relief when assessing the effects of cold deformation on mechanical properties.

Measurement of Viscoelastic Stress Relief in Patterned Silicon-on-Insulator Composite Structures With Raman Spectroscopy

1991 ◽  
Vol 239 ◽  
Author(s):  
T. J. Létavic ◽  
E. W. Maby ◽  
R. J. Gutmann ◽  
J. Petruzzello
Keyword(s):  
Raman Spectroscopy ◽  
Plane Stress ◽  
Composite Structures ◽  
Silicon Layer ◽  
Stress Relief ◽  
High Temperature Stress ◽  
Fused Silica ◽  
Silicon On Insulator ◽  
Active Device ◽  
Measured Strain

ABSTRACTRaman spectroscopy has been utilized to measure room-temperature residual strain in the active device layer of laser-recrystallized silicon-on-insulator (SOI) composite structures. The SOI composite structures were fabricated on synthetic fused-silica substrates, and the composites contained a phosphosilicate glass (PSG) layer to provide high-temperature stress relief. Conventional masking and etching techniques were used to selectively pattern the polycrys-talline silicon layer into isolated square islands prior to recrystallization. The biaxial in-plane stress in recrystallized films was calculated from the measured strain-induced first-order Stokes Raman wavenumber shifts, and the results indicate that 200- μm-square recrystallized silicon islands have significantly lower in-plane stress values than continuous recrystallized silicon films. These measurements provide a preliminary confirmation of the dependence of the time constant for viscoelastic stress relief on the in-plane pattern dimension.

Computing cell tractions from particle displacements on silicone rubber substrata

1994 ◽  
Vol 52 ◽  
pp. 162-163
Author(s):  
Tim Oliver ◽  
Akira Ishihara ◽  
Ken Jacobsen ◽  
Micah Dembo
Keyword(s):  
Plane Stress ◽  
Linear Elasticity ◽  
Silicone Rubber ◽  
Mathematical Analysis ◽  
Elastic Recovery ◽  
Video Images ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Better Than

In order to better understand the distribution of cell traction forces generated by rapidly locomoting cells, we have applied a mathematical analysis to our modified silicone rubber traction assay, based on the plane stress Green’s function of linear elasticity. To achieve this, we made crosslinked silicone rubber films into which we incorporated many more latex beads than previously possible (Figs. 1 and 6), using a modified airbrush. These films could be deformed by fish keratocytes, were virtually drift-free, and showed better than a 90% elastic recovery to micromanipulation (data not shown). Video images of cells locomoting on these films were recorded. From a pair of images representing the undisturbed and stressed states of the film, we recorded the cell’s outline and the associated displacements of bead centroids using Image-1 (Fig. 1). Next, using our own software, a mesh of quadrilaterals was plotted (Fig. 2) to represent the cell outline and to superimpose on the outline a traction density distribution. The net displacement of each bead in the film was calculated from centroid data and displayed with the mesh outline (Fig. 3).

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

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