scholarly journals Strain rate dependence of twinning avalanches at high speed impact

2014 ◽  
Vol 104 (16) ◽  
pp. 162906 ◽  
Author(s):  
L. Zhang ◽  
E. K. H. Salje ◽  
X. Ding ◽  
J. Sun
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
High Speed Impact

Temperatures at Interfacial Contact Spots: Dependence on Velocity and on Role Reversal of Two Materials in Sliding Contact

1987 ◽  
Vol 109 (2) ◽  
pp. 321-329 ◽  
Author(s):  
D. Kuhlmann-Wilsdorf
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Role Reversal ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Flash Temperature ◽  
Friction Heat ◽  
Elliptical Contact ◽  
Two Sides ◽  
Contact Spots

Based on the theory by Blok and Jaeger, simple equations have been obtained for the theoretical evaluation of flash temperatures, i.e., the temperatures of circular or elliptical contact spots between two homogeneous materials, when friction heat and/or Joule heat is evolved at the interface. The parameters appearing in the equations have been expressed in terms of experimental data, the coefficient of friction, known materials properties, and the ellipticity and number of contact spots. The equations are especially simple in the limiting cases of very high and of very low speeds, and were indeed known in these limits for circular, albeit not for elliptical contact spots. As an example, the flash temperatures of plastic contact spots on account of friction heat have been computed for (i) an electrical brush material sliding on copper, and (ii) a carbon steel sliding on itself. In these examples the dependence of the flash temperature on the velocity of the contact spots relative to either or both of the two sides has been investigated, wherein the effect of sliding rate on the flash temperature via the strain rate dependence of local hardness has been taken into consideration,- it is believed for the first time in any theoretical investigation of flash temperatures. In the high-speed case, in agreement with intuitive expectation, the numerical examples show that under otherwise same conditions and same macroscopic velocity, minimum flash temperature is attained when the spot moves relative to both sides. Typically, that minimum does not occur when the contact spot speed is one half of the relative speed on each of the two sides, however. Moreover, and somewhat unexpectedly, the results show that the previously neglected strain rate dependence of the hardness has a considerable effect.

scholarly journals Numerical Simulation of Tool/Abradable Material Interaction Experiments

2012 ◽  
Author(s):  
Alain Batailly ◽  
Marion Cuny ◽  
Mathias Legrand
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Robust Solution ◽  
Abradable Coating ◽  
Rotor Stator Interaction ◽  
Material Interaction ◽  
Numerical Strategy

Applying abradable coating on the casing of turbomachines has been widely recognized as a robust solution advantageously combining the adjustment of operating clearances with the reduction of potential non-repairable damages. Thus, the modeling of this material is a growing field of investigation. Based on the numerical strategy proposed and detailed in previous publication by the same authors, the present study aims at capturing the mechanical behavior of abradable coating in the context of high speed interaction with a rigid tool. The plastic law given is first enriched in order to take into account strain rate dependence. The sensitivity of the model regarding its main numerical parameters is assessed and highlights the role of each of these parameters. The calibration of numerical results with respect to experimental results lead to very satisfying results that confirm that the proposed strategy is well-suited for the modeling of abradable coating. Finally, the newly developped viscoplastic law is applied to a 3D rotor/stator interaction case to determine the criticity of strain rate dependence in the case of blade/casing contact.

scholarly journals Numerical-Experimental Confrontation in the Simulation of Tool/Abradable Material Interaction

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Alain Batailly ◽  
Marion Cuny ◽  
Mathias Legrand ◽  
Sylvain Philippon
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Three Dimensional ◽  
Rate Dependence ◽  
Constitutive Law ◽  
Strain Rate Dependence ◽  
Robust Solution ◽  
Rotor Stator Interaction ◽  
Abradable Coatings ◽  
Material Interaction

In turbomachinery, depositing abradable coatings along the circonference of casings is recognized as a robust solution which combines the adjustment of operating clearances with the reduction of nonrepairable damages potentially affecting the rotating blades. Accordingly, the modeling of the removal process experienced by these materials is of growing industrial importance. Based on a numerical strategy detailed in a previous publication by the authors, the present study aims at describing the mechanical behavior of abradable coatings used within turbomachines in the context of translational high-speed interactions with a rigid tool. The developed plastic constitutive law macroscopically capturing the abradable material removal is first enriched to account for its strain rate dependence. Then, a sensitivity analysis with respect to a few parameters of interest is conducted and calibration of the numerical investigation with existing experimental data validates the proposed approach. Finally, the strain-rate dependence of the viscoplastic law implemented within a full numerical three-dimensional rotor/stator interaction is addressed. Results reveal that viscoplastic terms have minor effects in turbomachinery interactions.

scholarly journals Strain Rate Dependence of Flow Stress in Steels Measured by High Speed Hot Torsion Tests

1967 ◽  
Vol 53 (11) ◽  
pp. 1218-1222
Author(s):  
Tadahisa NAKAMURA ◽  
Seita SAKUI ◽  
Yuzo OHTAKARA
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
High Speed ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Hot Torsion

scholarly journals Reduced preload increases Mechanical Control (strain-rate dependence) of relaxation by modifying myosin kinetics

2021 ◽  
pp. 108909
Author(s):  
Brianna M. Schick ◽  
Hunter Dlugas ◽  
Teresa L. Czeiszperger ◽  
Alexandra R. Matus ◽  
Melissa J. Bukowski ◽  
...  
Keyword(s):  
Strain Rate ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Control Strain ◽  
Mechanical Control
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