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A Comprehensive Review of Experience with the Application of the Mechanical Threshold Stress Model
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作者 Paul S. Follansbee 《Materials Sciences and Applications》 CAS 2023年第5期299-323,共25页
Accurate prediction of stress-strain behavior of metals as a function of arbitrary temperature and strain rate paths has remained a challenge. The Mechanical Threshold Stress constitutive model is one formalism that h... Accurate prediction of stress-strain behavior of metals as a function of arbitrary temperature and strain rate paths has remained a challenge. The Mechanical Threshold Stress constitutive model is one formalism that has emerged following several decades of research. Vast experience has accumulated with the application of the Mechanical Threshold Stress model over a wide variety of pure metals and alloys. Out of this has arisen common trends across metal systems. The magnitude of activation energies presents one example of this, where these variables consistently increase in magnitude as the obstacle to dislocation motion transitions from short range to long range. Trends in strain hardening are also observed. In Face-Centered Cubic metals the magnitude of strain hardening scales with the stacking fault energy;trends in Body-Centered Cubic metals are less clear. Model parameters derived for over twenty metals and alloys are tabulated. Common trends should guide future application of the MTS model and further model development. 展开更多
关键词 mechanical threshold Stress Constitutive Behavior Deformation Kinetics Strain Hardening Internal State Variable
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Application of the Mechanical Threshold Stress Model to Large Strain Processing
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作者 Paul S. Follansbee 《Materials Sciences and Applications》 2022年第5期300-316,共17页
Large-strain deformations introduce several confounding factors that affect the application of the Mechanical Threshold Stress model. These include the decrease with the increasing stress of the normalized activation ... Large-strain deformations introduce several confounding factors that affect the application of the Mechanical Threshold Stress model. These include the decrease with the increasing stress of the normalized activation energy characterizing deformation kinetics, the tendency toward Stage IV hardening at high strains, and the influence of crystallographic texture. Minor additions to the Mechanical Threshold Stress model are introduced to account for variations of the activation energy and the addition of Stage IV hardening. Crystallographic texture cannot be modeled using an isotropic formulation, but some common trends when analyzing predominantly shear deformation followed by uniaxial deformation are described. Comparisons of model predictions with measurements in copper processed using Equal Channel Angular Pressing are described. 展开更多
关键词 mechanical threshold Stress Model Large-Strain Deformations ECAP Stress-Strain Curves Shear Deformations Activation Energy STRAIN-HARDENING
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Neurotoxicity of intrathecal injections of dexmedetomidine into the rat spinal dorsal horn 被引量:4
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作者 Jiabao Hou Zhongyuan Xia Xingpeng Xiao Xing Wan Bo Zhao 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第23期1765-1770,共6页
To investigate the neurotoxicity of intrathecal injections of dexmedetomidine,Sprague-Dawley rats were intrathecally injected with dexmedetomidine at doses of 0.75,1.50 and 3.00μg/kg into the spinal dorsal horn.We fo... To investigate the neurotoxicity of intrathecal injections of dexmedetomidine,Sprague-Dawley rats were intrathecally injected with dexmedetomidine at doses of 0.75,1.50 and 3.00μg/kg into the spinal dorsal horn.We found that c-Fos expression in the rat spinal dorsal horn peaked at 7 hours following the 3.00μg/kg dexmedetomidine injection,while the levels of c-Fos expression following 0.75 and 1.50μg/kg dexmedetomidine were similar to those in the spinal dorsal horn of normal rats. At 48 hours following administration,the level of c-Fos expression was similar to normal levels.In addition,the intrathecal injections of dexmedetomidine increased paw withdrawal mechanical thresholds and prolonged thermal tail flick latencies.These results indicate that dexmedetomidine has pronounced antinociceptive effects.However,dexmedetomidine appears to have neurotoxic effects in the spinal cord because it increased c-Fos expression in the spinal dorsal horn within 7 hours following administration. 展开更多
关键词 DEXMEDETOMIDINE drug toxicity spinal cord FOS paw withdrawal mechanical threshold thermal tail flick latency
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