scholarly journals Deformation response of cube-on-cube and non-coherent twin interfaces in AgCu eutectic under dynamic plastic compression

2018 ◽  
Vol 712 ◽  
pp. 313-324 ◽  
Author(s):  
B.P. Eftink ◽  
N.A. Mara ◽  
O.T. Kingstedt ◽  
D. Safarik ◽  
S. Wang ◽  
...  
Keyword(s):  
Deformation Response ◽  
Plastic Compression

Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

2020 ◽  
Vol 86 (10) ◽  
pp. 46-55
Author(s):  
S. I. Eleonsky ◽  
Yu. G. Matvienko ◽  
V. S. Pisarev ◽  
A. V. Chernov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Accumulation Process ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

scholarly journals Biomechanical Measurement of Rabbit Cornea by a Modified Scheimpflug Device

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Bo Zhang ◽  
Jianjun Gu ◽  
Xiaoxiao Zhang ◽  
Bin Yang ◽  
Zheng Wang ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Intraclass Correlation ◽  
Anterior Segment ◽  
Intraobserver Reliability ◽  
Rabbit Cornea ◽  
Deformation Response ◽  
Biomechanical Measurements ◽  
Biomechanical Measurement

Purpose. To explore the probability and variation in biomechanical measurements of rabbit cornea by a modified Scheimpflug device.Methods. A modified Scheimpflug device was developed by imaging anterior segment of the model imitating the intact eye at various posterior pressures. The eight isolated rabbit corneas were mounted on the Barron artificial chamber and images of the anterior segment were taken at posterior pressures of 15, 30, 45, 60, and 75 mmHg by the device. The repeatability and reliability of the parameters including CCT, ACD, ACV, and CV were evaluated at each posterior pressure. All the variations of the parameters at the different posterior pressures were calculated.Results. All parameters showed good intraobserver reliability (Cronbach’s alpha; intraclass correlation coefficient,α, ICC > 0.96) and repeatability in the modified Scheimpflug device. With the increase of posterior pressures, the ratio of CCT decreased linearly and the bulk modulus gradually reduced to a platform. The increase of ACD was almost linear with the posterior pressures elevated.Conclusions. The modified Scheimpflug device was a valuable tool to investigate the biomechanics of the cornea. The posterior pressure 15–75 mmHg range produced small viscoelastic deformations and nearly linear pressure-deformation response in the rabbit cornea.

The role of brass texture on the deformation response of 7075-T651 aluminum alloy under equi-biaxial tension

2021 ◽  
pp. 141133
Author(s):  
Nedunchezhian Srinivasan ◽  
R. Velmurugan ◽  
Lalith Kumar Bhaskar ◽  
Satish Kumar Singh ◽  
Bhanu Pant ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Biaxial Tension ◽  
Deformation Response

scholarly journals Deformation response and anchorage control of excavation unloading of high and steep rock slope

2020 ◽  
Vol 570 ◽  
pp. 042010
Author(s):  
Zhihong Dong ◽  
Xiuli Ding ◽  
Shuling Huang ◽  
Yongjin Wu ◽  
Aiqing Wu
Keyword(s):  
Rock Slope ◽  
Deformation Response

scholarly journals A Simplified Analysis Method for the Deformation Response of an Existing Tunnel to Ground Surcharge Based on the Pasternak Model

2021 ◽  
Vol 11 (7) ◽  
pp. 3255
Author(s):  
Zheng Wei ◽  
Yusheng Jiang
Keyword(s):  
Longitudinal Displacement ◽  
Maximum Displacement ◽  
Deformation Response ◽  
Reaction Coefficient ◽  
Element Simulation ◽  
Tunnel Model ◽  
Calculation Results ◽  
Pasternak Model ◽  
Boussinesq Solution ◽  
Euler Bernoulli Beam

Surface surcharge changes the existing equilibrium stress field of the stratum and adversely affects the existing tunnel. This paper presents a simplified analytical solution for calculating the longitudinal displacement of existing tunnels that are subjected to adjacent surcharge loading. Based on the Boussinesq solution, the distribution of the additional load matrix caused by the surface surcharge on the existing tunnel was obtained. A Euler–Bernoulli beam with a Pasternak foundation was used as a simplified model for tunnel stress analysis. Using the corrected reaction coefficient of the foundation bed, the differential equation of tunnel deformation was established, and the solution matrix of the longitudinal displacement of the tunnel was obtained by using the finite difference method. The reliability and applicability of the proposed method were verified by comparing the results with finite element simulation results, field test data, and the calculation results of three simplified elastic analysis methods with different foundation bed coefficients. On this basis, the parameters of the load–tunnel model were analyzed, and the effects of the buried depth, the size of the load, the relative positions of the load and the tunnel, and the relative stiffness of the tunnel soil on the maximum displacement of the existing tunnel were calculated. An empirical formula is proposed for calculating the maximum longitudinal displacement of the existing tunnel subjected to surface surcharge. The findings of this research can provide a basis for the theoretical verification of the deformation response of an existing tunnel subjected to adjacent surface surcharge.

The Role of Mechanical Tension in Neurons

2010 ◽  
Vol 1274 ◽  
Author(s):  
Taher Saif ◽  
Jagannathan Rajagopalan ◽  
Alireza Tofangchi
Keyword(s):  
Mechanical Response ◽  
Mechanical Forces ◽  
Active Tension ◽  
Mechanical Tension ◽  
Deformation Response ◽  
Linear Force ◽  
Tension Regulation ◽  
Over Time

AbstractWe used high resolution micromechanical force sensors to study the in vivo mechanical response of embryonic Drosophila neurons. Our experiments show that Drosophila axons have a rest tension of a few nN and respond to mechanical forces in a manner characteristic of viscoelastic solids. In response to fast externally applied stretch they show a linear force-deformation response and when the applied stretch is held constant the force in the axons relaxes to a steady state value over time. More importantly, when the tension in the axons is suddenly reduced by releasing the external force the neurons actively restore the tension, sometimes close to their resting value. Along with the recent findings of Siechen et al (Proc. Natl. Acad. Sci. USA 106, 12611 (2009)) showing a link between mechanical tension and synaptic plasticity, our observation of active tension regulation in neurons suggest an important role for mechanical forces in the functioning of neurons in vivo.

scholarly journals SHEARING TESTS APPLIED TO PANTOGRAPHIC STRUCTURES

2016 ◽  
Vol 7 ◽  
pp. 1 ◽  
Author(s):  
Gregor Ganzosch ◽  
Francesco Dell’Isola ◽  
Emilio Turco ◽  
Tomasz Lekszycki ◽  
Wolfgang H. Müller
Keyword(s):  
Rapid Manufacturing ◽  
Pantographic Structures ◽  
Deformation Response ◽  
Shear Loads ◽  
Generalized Continuum ◽  
Complete Failure ◽  
Elastic Cylinders ◽  
Inextensible Fibers ◽  
Fabric Materials ◽  
Continuum Theories

With the advancements in 3D printing technology, rapid manufacturing of fabric materials with complex geometries became possible. By exploiting this technique, different materials with different structures have been developed in the recent past with the objective of making generalized continuum theories useful for technological applications. So-called pantographic structures are introduced: Inextensible fibers are printed in two arrays orthogonal to each other in parallel planes. These superimposed planes are inter-connected by elastic cylinders. Five differently-sized samples were subjected to shear-like loading while their deformation response was analyzed. Results show that deformation behavior is strong non-linear for all samples. Furthermore, all samples were capable to resist considerable external shear loads without leading to complete failure of the whole structure. This extraordinary behavior makes these structures attractive to serve as an extremely tough metamaterial.

On the Utility of Crystal Plasticity Modeling to Uncover the Individual Roles of Microdeformation Mechanisms on the Work Hardening Response of Fe-23Mn-0.5C TWIP Steel in the Presence of Hydrogen

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
B. Bal ◽  
M. Koyama ◽  
D. Canadinc ◽  
G. Gerstein ◽  
H. J. Maier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Embrittlement ◽  
Twip Steel ◽  
Strain Response ◽  
Deformation Response ◽  
Self Consistent ◽  
Twip Steels ◽  
Simulation Results ◽  
The Individual ◽  
Experimental Findings

This paper presents a combined experimental and theoretical analysis focusing on the individual roles of microdeformation mechanisms that are simultaneously active during the deformation of twinning-induced plasticity (TWIP) steels in the presence of hydrogen. Deformation responses of hydrogen-free and hydrogen-charged TWIP steels were examined with the aid of thorough electron microscopy. Specifically, hydrogen charging promoted twinning over slip–twin interactions and reduced ductility. Based on the experimental findings, a mechanism-based microscale fracture model was proposed, and incorporated into a visco-plastic self-consistent (VPSC) model to account for the stress–strain response in the presence of hydrogen. In addition, slip-twin and slip–grain boundary interactions in TWIP steels were also incorporated into VPSC, in order to capture the deformation response of the material in the presence of hydrogen. The simulation results not only verify the success of the proposed hydrogen embrittlement (HE) mechanism for TWIP steels, but also open a venue for the utility of these superior materials in the presence of hydrogen.

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