A damage-mechanism-based creep model considering temperature effect in granite

Laser-induced thermal–mechanical damage characteristics of window materials are the focus problems in laser weapon and anti-radiation reinforcement technology. Thermal–mechanical effects and damage characteristics are investigated for cleartran multispectral zinc sulfide ( ZnS ) thin film window materials irradiated by continuous laser using three-dimensional (3D) thermal–mechanical model. Some temperature-dependent parameters are introduced into the model. The temporal-spatial distributions of temperature and thermal stress are exhibited. The damage mechanism is analyzed. The influences of temperature effect of material parameters and laser intensity on the development of thermal stress and the damage characteristics are examined. The results show, the von Mises equivalent stress along the thickness direction is fluctuant, which originates from the transformation of principal stresses from compressive stress to tensile stress with the increase of depth from irradiated surface. The damage originates from the thermal stress but not the melting. The thermal stress is increased and the damage is accelerated by introducing the temperature effect of parameters or the increasing laser intensity.

Download Full-text

Deformation-mechanism-based creep model and damage mechanism of G115 steel over a wide stress range

Materials Science and Engineering A ◽

10.1016/j.msea.2018.11.083 ◽

2019 ◽

Vol 743 ◽

pp. 280-293 ◽

Cited By ~ 6

Author(s):

Bo Xiao ◽

Lianyong Xu ◽

Lei Zhao ◽

Hongyang Jing ◽

Yongdian Han

Keyword(s):

Deformation Mechanism ◽

Damage Mechanism ◽

Creep Model ◽

Stress Range

Download Full-text

A triaxial creep model for deep coal considering temperature effect based on fractional derivative

Acta Geotechnica ◽

10.1007/s11440-021-01302-w ◽

2021 ◽

Author(s):

Lei Zhang ◽

Hongwei Zhou ◽

Xiangyu Wang ◽

Lei Wang ◽

Teng Su ◽

...

Keyword(s):

Fractional Derivative ◽

Temperature Effect ◽

Creep Model ◽

Triaxial Creep

Download Full-text

Elemental mass loss in silicate minerals during x-ray analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177155 ◽

1990 ◽

Vol 48 (4) ◽

pp. 804-805

Author(s):

P.E. Champness ◽

R.W. Devenish

Keyword(s):

Mass Loss ◽

Current Density ◽

Damage Mechanism ◽

Beam Current ◽

Single Chain ◽

Plagioclase Feldspar ◽

X Ray ◽

Alkali Ions ◽

Structural Order ◽

Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

Download Full-text

Temperature effect on friction coefficient in stamping of coated stelle sheets

Matériaux & Techniques ◽

10.1051/mattech/199381010088 ◽

1993 ◽

Vol 81 (1-2-3) ◽

pp. 88-92

Author(s):

Y. Renault

Keyword(s):

Friction Coefficient ◽

Temperature Effect

Download Full-text

Parallel Glide: A Fundamentally Different Type of Dislocation Motion in Ultrathin Metal Films

MRS Proceedings ◽

10.1557/proc-779-w4.4 ◽

2003 ◽

Vol 779 ◽

Author(s):

T. John Balk ◽

Gerhard Dehm ◽

Eduard Arzt

Keyword(s):

Thermal Cycling ◽

Grain Boundaries ◽

Film Surface ◽

Metal Films ◽

Geometric Constraints ◽

Film Stress ◽

Diffusional Creep ◽

Creep Model ◽

Substrate Interface ◽

Film Substrate

AbstractWhen confronted by severe geometric constraints, dislocations may respond in unforeseen ways. One example of such unexpected behavior is parallel glide in unpassivated, ultrathin (200 nm and thinner) metal films. This involves the glide of dislocations parallel to and very near the film/substrate interface, following their emission from grain boundaries. In situ transmission electron microscopy reveals that this mechanism dominates the thermomechanical behavior of ultrathin, unpassivated copper films. However, according to Schmid's law, the biaxial film stress that evolves during thermal cycling does not generate a resolved shear stress parallel to the film/substrate interface and therefore should not drive such motion. Instead, it is proposed that the observed dislocations are generated as a result of atomic diffusion into the grain boundaries. This provides experimental support for the constrained diffusional creep model of Gao et al.[1], in which they described the diffusional exchange of atoms between the unpassivated film surface and grain boundaries at high temperatures, a process that can locally relax the film stress near those boundaries. In the grains where it is observed, parallel glide can account for the plastic strain generated within a film during thermal cycling. One feature of this mechanism at the nanoscale is that, as grain size decreases, eventually a single dislocation suffices to mediate plasticity in an entire grain during thermal cycling. Parallel glide is a new example of the interactions between dislocations and the surface/interface, which are likely to increase in importance during the persistent miniaturization of thin film geometries.

Download Full-text