scholarly journals Spongy bone deformation mechanisms

2009 ◽  
pp. 67-79
Author(s):  
Fahmi Chaari ◽  
Julien Halgrin ◽  
Éric Markiewicz ◽  
Pascal Drazetic
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
Deformation Mechanisms ◽  
Compression Tests ◽  
Rate Dependency ◽  
Compression Force ◽  
Sample Shape ◽  
Final Sample ◽  
Constitutive Material ◽  
Cylindrical Samples

In order to identify the spongy bone's mechanical behaviour, we performed compression tests on cylindrical samples. Experimental results show important dispersions and an unexpected inverse strain rate dependency at low range of loading velocities. The origin of the dispersions can be attributed to the combination of the architecture effect and the mechanical properties variation of the constitutive material. In order to understand the inverse strain rate sensitivity, we used a controlled constitutive material to build new equivalent samples with the spongy bone's architecture. These samples were subjected to compression tests. Numerical simulations of compression tests on the same architecture have been carried out with FE models built from μCt data. The obtained results are compared in term of final sample shape and the evolution of the compression force.

Hot Deformation Studies of a Low Carbon Steel Containing V

2013 ◽  
Vol 554-557 ◽  
pp. 1224-1231 ◽  
Author(s):  
Cecilia Poletti ◽  
Martina Dikovits ◽  
Javier Ruete
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
True Strain ◽  
Low Carbon Steel ◽  
Dynamic Effect ◽  
Rate Sensitivity ◽  
Low Carbon ◽  
Compression Tests ◽  
Deformation Parameters

Low alloyed steels produced by continuous casting are thermomechanically treated to achieve final high mechanical properties, meaning a good combination of strength and toughness. The hot deformation mechanisms of a micro-alloyed steel containing up to 0.1wt% of V is studied by means of hot compression tests using a Gleeble®3800 device. Austenitization of samples is carried out at 1150°C during 2 minutes followed by cooling to the deformation temperature at 1Ks-1in the range of 750 – 1150°C. The studied strain rate range is from 0.01 to 80 s-1and the total true strain achieved is of 0.7. In situ water quenching is applied after the deformation to freeze the microstructure and avoid any post dynamic effect. The Ar3temperature is determined by dilatometry experiments to be 725°C for the used cooling rate. The stress values obtained from the compression tests are evaluated at different strains to determine the strain rate sensitivity and flow instability maps and thus, to predict the formability of the material in the range of studied deformation parameters. These maps are correlated to the microstructure at specific deformation parameters.

Strain Rate Sensitivity of Ultrafine-Grained CP-Ti Processed by ECAP at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 707-712 ◽  
Author(s):  
Xiao Yan Liu ◽  
Xi Cheng Zhao ◽  
Xi Rong Yang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Ultrafine Grained ◽  
Die Set ◽  
Increasing Temperature ◽  
Cp Ti

Ultrafine-grained (UFG) commercially pure (CP) Ti with a grain size of about 200 nm was produced by ECAP up to 8 passes using route BC at room temperature. For ECAP processing a proper die set was designed and constructed with an internal channel angle Φ of 120° and an outer arc of curvature Ψ of 20°. Strain rate sensitivity of UFG CP-Ti and CG CP-Ti were investigated by compression tests in the temperature range of 298~673K and strain rate range of 10-4~100s-1 using Gleeble simulator machine. Evolution of the microstructure during compression testing was observed using optical microscopy (OM) and transmission electron microscopy (TEM). Strain rate sensitivity value m of the UFG CP-Ti has been measured and is found to increase with increasing temperature and decreasing strain rate, and is enhanced compared to that of CG CP-Ti. Result of the deformation activation energy determination of UFG CP-Ti indicates that the deformation mechanism in UFG CP-Ti is correlated to the grain boundaries.

scholarly journals Tensile and Stress-Rupture Behavior of Hafnium Carbide Dispersed Molybdenum and Tungsten Base Alloy Wires

1993 ◽  
Vol 322 ◽  
Author(s):  
H.M. Yun ◽  
R.H. Titran
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rupture Strength ◽  
Base Alloy ◽  
Stress Rupture ◽  
Rate Sensitivity ◽  
Tungsten Alloy ◽  
Rate Dependency ◽  
Hafnium Carbide ◽  
Stress Rupture Strength

AbstractThe tensile strain rate sensitivity and the stress-rupture strength of Mo-base and W-base alloy wires, 380 µm in diameter, were determined over the temperature range from 1200 to 1600 K. Three molybdenum alloy wires; Mo + 1.1 wt% hafnium carbide (MoHfC), Mo + 25 wt% W + 1.1 wt% hafnium carbide (MoHfC+25W) and Mo + 45 wt% W + 1.1 wt% hafnium carbide (MoHfC+45W), and a W + 0.4 wt% hafnium carbide (WHfC) tungsten alloy wire were evaluated.The tensile strength of all wires studied was found to have a positive strain rate sensitivity. The strain rate dependency increased with increasing temperature and is associated with grain broadening of the initial fibrous structures. The hafnium carbide dispersed W-base and Mo-base alloys have superior tensile and stress-rupture properties than those without HfC. On a density compensated basis the MoHfC wires exhibit superior tensile and stress-rupture strengths to the WHfC wires up to approximately 1400 K. Addition of tungsten in the Mo-alloy wires was found to increase the long-term stress-rupture strength at temperatures above 1400 K.

Hot isostatic pressing synthesis and mechanical properties of Al/Al–Cu–Fe composite materials

2008 ◽  
Vol 23 (4) ◽  
pp. 904-910 ◽  
Author(s):  
T. El Kabir ◽  
A. Joulain ◽  
V. Gauthier ◽  
S. Dubois ◽  
J. Bonneville ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Hot Isostatic Pressing ◽  
Constant Strain Rate ◽  
Rate Sensitivity ◽  
Icosahedral Phase ◽  
Compression Tests ◽  
Isostatic Pressing ◽  
Temperature Regimes ◽  
Mechanism Control

Metal-matrix composites are produced from Al powder and 30 vol% of icosahedral Al–Cu–Fe quasi-crystalline particles using a hot isostatic pressing technique. It is demonstrated that the initial icosahedral phase is transformed into the ω-Al70Cu20Fe10 tetragonal phase during the hot isostatic pressing (HIP) process. The mechanical properties of the composite were evaluated over the temperature range 293 to 773 K by performing compression tests at constant strain rate. The temperature dependence of the yield stress gives evidence of two temperature regimes with a transition temperature at approximately 423 K. Strain-rate sensitivity measurements support the change in rate-controlling deformation mechanisms at this temperature. It is proposed that cross-slip and/or climb mechanism control plastic flow. Finally, it is suggested that the phase transformation of the particle contributes positively to the improvement of the mechanical properties.

Deformation Heating and Its Effect on the Processing Maps of Ti-15-3 Titanium Alloy

2013 ◽  
Vol 712-715 ◽  
pp. 58-64
Author(s):  
Jing Qi Zhang ◽  
Hong Shuang Di ◽  
Xiao Yu Wang
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Compression Tests ◽  
Temperature Range ◽  
Deformation Heating ◽  
Instability Criteria ◽  
Flow Stress Data

In the present study, deformation heating generated by plastic deformation and its effect on the processing maps of Ti-15-3 titanium alloy were investigated. For this purpose, hot compression tests were performed on a Gleeble-3800 thermo-mechanical simulator in the temperature range of 850-1150 °C and strain rate range of 0.001-10 s1. The temperature rise due to deformation heating was calculated and the as-measured flow curves were corrected for deformation heating. Using the as-measured and corrected flow stress data, the processing maps for Ti-15-3 titanium alloy at a strain of 0.5 were developed on the basis Murty‘s and Babu’s instability criteria. The results show that both the instability maps based the two instability criteria are essentially similar and are characterized by an unstable region occurring at strain rates higher than 0.1 s1for almost the entire temperature range tested. The unstable regions are overestimated from the as-measured data due to the effect of deformation heating, indicating a better workability after correcting the effect of deformation heating. This is further conformed by the analysis based on strain rate sensitivity.

Hot Workability Analysis of Extruded Mg-Zn-Mn-Y Magnesium Alloys with Different Phases

2012 ◽  
Vol 184-185 ◽  
pp. 1010-1016
Author(s):  
Wei Wei He ◽  
Kun Zhang ◽  
Min Huang ◽  
Sheng Long Dai
Keyword(s):  
Strain Rate ◽  
Magnesium Alloys ◽  
Power Dissipation ◽  
Rate Sensitivity ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Secondary Phases ◽  
Forming Process ◽  
Power Dissipation Efficiency

Workability, an important parameter in magnesium alloys forming process, can be evaluated by means of processing maps on the basis of dynamic materials model, constructed from experimentally generated flow stress variation with respect to strain, strain rate and temperature. To obtain the processing maps of extruded Mg-Zn-Mn-Y magnesium alloy with different secondary phases (I-phase and W-phase), hot compression tests were performed over a range of temperatures 523–673 K and strain rates 0.001~10s-1. The response of strain-rate sensitivity (m-value), power dissipation efficiency (ζ-value) and instability parameter (n-value) to temperature and strain rate were evaluated. By the superimposition of the power dissipation and the instability maps, the dynamic recrystallization (DRX) and instability zones were identified and validated through micrographs. The observations were performed in order to describe the behavior of the material under hot forming operation in terms of material damage and micro-structural modification.

Elastic and pseudoviscous properties of coal under quasi-static and impact loadings

1984 ◽  
Vol 21 (2) ◽  
pp. 203-212 ◽  
Author(s):  
J. R. Klepaczko ◽  
T. R. Hsu ◽  
M. N. Bassim
Keyword(s):  
Strain Rate ◽  
Elastic Properties ◽  
Viscoelastic Properties ◽  
Viscoelastic Model ◽  
Rate Sensitivity ◽  
Bedding Plane ◽  
Strain Rates ◽  
Compression Tests ◽  
Wide Range ◽  
Coefficient Of Viscosity

An investigation of the elastic and viscoelastic properties of Nova Scotia coal was carried out over a wide range of strain rates (quasi-static to impact). High resolution stress–strain diagrams for the coal were obtained from compression tests for the lower and medium strain rates up to [Formula: see text] and with the split Hopkinson bar technique for the high strain rate region up to [Formula: see text].The elastic properties of the coal showed a moderate rate sensitivity at low and moderate strain rates.Above the strain rate [Formula: see text] both Young's modulus and the stress level of microcracking initiation σf0isplayed extreme rate sensitivity and was found to be a linear function of strain rate. The associated coefficient of viscosity perpendicular to the bedding plane was η* = 3.08 × 104 Pa∙s.The viscoelastic model so determined can be used to assess the elastic properties of coal at even higher strain rates, a situation that is similar to an explosive loading. Keywords: coal, strain rates, dynamic, viscoelastic properties.

Mechanical Anisotropy and Strain Rate Dependency Behavior of Ti6Al4V Produced Using E-Beam Additive Fabrication

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Leila Ladani ◽  
Jafar Razmi ◽  
Soud Farhan Choudhury
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Mechanical Anisotropy ◽  
Rate Dependency ◽  
Out Of Plane ◽  
Degree Of Anisotropy ◽  
Strain Rate Dependency

Anisotropic mechanical behavior is an inherent characteristic of parts produced using additive manufacturing (AM) techniques in which parts are built layer by layer. It is expected that in-plane and out-of-plane properties be different in these parts. E-beam fabrication is not an exception to this. It is, however, desirable to keep this degree of anisotropy to a minimum level and be able to produce parts with comparable mechanical strength in both in-plane and out-of-plane directions. In this manuscript, this degree of anisotropy is investigated for Ti6Al4V parts produced using this technique through tensile testing of parts built in different orientations. Mechanical characteristics such as Young's modulus, yield strength (YS), ultimate tensile strength (UTS), and ductility are evaluated. The strain rate effect on mechanical behavior, namely, strength and ductility, is also investigated by testing the material at a range of strain rates from 10−2 to 10−4 s−1. Local mechanical properties were extracted using nanoindentation technique and compared against global values (average values obtained by tensile tests). Although the properties obtained in this experiment were comparable with literature findings, test results showed that in-plane properties, elastic modulus, YS, and UTS are significantly higher than out-of-plane properties. This could be an indication of defects in between layers or imperfect bonding of the layers. Strong positive strain rate sensitivity was observed in out-of-plane direction. The strain rate sensitivity evaluation did not show strain rate dependency for in-plane directions. Local mechanical properties obtained through nanoindentation confirmed the findings of tensile test and also showed variation of properties caused by geometry.

Rubber Structural Coupon Behaviour Study under Pressure Impulse

2013 ◽  
Vol 198 ◽  
pp. 394-399
Author(s):  
Pawel Baranowski ◽  
Jerzy Malachowski ◽  
Łukasz Mazurkiewicz ◽  
Krzysztof Damaziak
Keyword(s):  
Strain Rate ◽  
Time Integration ◽  
Rate Sensitivity ◽  
Rate Dependency ◽  
Material Behaviour ◽  
Explicit Integration ◽  
Dynamic Simulations ◽  
Central Difference ◽  
Strain Rate Effects ◽  
Behaviour Study

This study focuses on the rubber material behaviour assessment under dynamic loading using numerical methods. Consequently, dynamic simulations of the rubber structural coupon subjected to dynamic velocity loading were performed using the explicit integration procedure with central difference scheme with modified time integration of the equation of motion implementation. During investigations two impulse velocities were used and compared for two different constitutive materials: Mooney-Rivlin without rate-dependency and Mat 181 Simplified Rubber which includes strain rate effects. From the obtained results it was noticed that material behaviour in both cases is different and along with different values of velocity the strain rate sensitivity changes.

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