A damage evolution rate controlled method for catastrophic failure process of metal films

2021 ◽  
pp. 103929
Author(s):  
Bin Sun ◽  
Xingzhen Huang ◽  
Zhaodong Xu
Keyword(s):  
Damage Evolution ◽  
Failure Process ◽  
Metal Films ◽  
Evolution Rate ◽  
Catastrophic Failure ◽  
Rate Controlled

Damage Observation and Analysis of a Rock Brazilian Disc Using High-Speed DIC Method

2011 ◽  
Vol 70 ◽  
pp. 87-92 ◽  
Author(s):  
Shao Peng Ma ◽  
Dong Yan ◽  
Xian Wang ◽  
Yan Yan Cao
Keyword(s):  
Strain Field ◽  
Damage Evolution ◽  
High Speed ◽  
Failure Process ◽  
Tensile Load ◽  
Brazilian Test ◽  
Elastic Model ◽  
Strain Fields ◽  
Brazilian Disc ◽  
Damage And Failure

Observation of damage evolution is of great importance to the understanding of the failure process of rock materials. High-speed DIC system is constructed and used to observe the strain field evolution of the granodiorite disc in Brazilian test. The strain fields at different load levels are analyzed based on the stain abnormality indicator (SAI) which is the ratio of the strain measured in experiment to the strain from theoretical solution in an isotropy and elastic model. SAI could be used to indicate the damage in the specimen. The process of damage and failure of the specimen in Brazilian disc test is quantitatively analyzed and deeply discussed according to the strain fields and the statistics of SAI. Experimental results in this paper show that the failure process of the disc specimen in Brazilian test is not simple crack propagation under tensile load, but a complicated damage evolution procedure.

Cyclic Cohesive Zone Model for Simulation of Fatigue Failure Process in Adhesive Joints

2014 ◽  
Vol 606 ◽  
pp. 217-221 ◽  
Author(s):  
Mahzan Johar ◽  
Mohamad Shahrul Effendy Kosnan ◽  
Mohd Nasir Tamin
Keyword(s):  
Fatigue Failure ◽  
Adhesive Joint ◽  
Cohesive Zone ◽  
Damage Evolution ◽  
Cohesive Zone Model ◽  
Failure Process ◽  
Interface Strength ◽  
Zone Model ◽  
Strength And Stiffness ◽  
Cyclic Damage

Progressive failure process of adhesive joint under cyclic loading is of particular interest in this study. Such fatigue failure is described using damage mechanics with the assumed cohesive behaviour of the adhesive joint. Available cohesive zone model for monotonic loading is re-examined for extension to capture cyclic damage process of adhesive joints. Damage evolution in the adhesive joint is expressed in terms of cyclic degradation of interface strength and stiffness. Mixed-mode fatigue fracture of the joint is formulated based on relative displacements and strain energy release rate of the interface. A power-law type variation for each of these cohesive zone model parameters with accumulated load cycles is assumed in the presence of limited experimental data on cyclic interface fracture process. The cyclic cohesive zone model (CCZM) is implemented in commercial finite element analysis code and the model is validated using adhesively bonded 2024-T3 aluminium substrates with epoxy-based adhesive film (FM73M OST). The CCZM model is then examined for cyclic damage evolution characteristics of the adhesive lap joint subjected to cyclic displacement of Δδ = 0.1 mm, R=0 so as to induce shear-dominant fatigue failure. Results show that the cyclic interface damage started to initiate and propagate symmetrically from the both overlap edges and degradation of interface strength and stiffness started to accumulate after 0.5 cycles of displacement elapsed. The predicted results are consistent with the mechanics of relatively brittle interface failure process.

scholarly journals Statistical Constitutive Model of Thermal Damage for Deep Rock considering Initial Compaction Stage and Residual Strength

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Lingjie Zhu ◽  
Xiaoli Xu ◽  
Xiaojian Cao ◽  
Shaoyong Chen
Keyword(s):  
Constitutive Model ◽  
Residual Strength ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Thermal Damage ◽  
Peak Stress ◽  
Confining Pressure ◽  
Evolution Rate ◽  
Correction Coefficient ◽  
Initial Compaction

From the theory of damage mechanics, based on the Hoek-Brown strength criterion and Weibull distribution law of rock microelement strength, a statistical constitutive model of rock thermal damage is established by using equivalent strain hypothesis, and the theoretical model is modified by considering the compression coefficient and residual strength correction coefficient. The rationality of the modified model is verified by experimental data. The results show that the stress-strain curves of rock can be divided into four stages: initial compaction, stable damage propagation, damage strengthening expansion, and damage failure according to the characteristics of rock damage evolution. The peak stress of rock increases exponentially with the increase of confining pressure, and the maximum damage evolution rate decreases exponentially with the increase of confining pressure, which indicates that confining pressure delays the development of cumulative damage. The peak stress and maximum damage evolution rate of rock decrease exponentially with the increase of temperature, which accelerates the damage of rock. The initial damage of rock is thermal damage caused by temperature, and the damage value increases with the increase of temperature. The revised theoretical curve reflects the characteristics of rock compaction stage and residual strength and improves the coincidence with the experimental curve. The research results provide a reference for the establishment of thermal damage constitutive model of rock in deep engineering.

Fire Response Calculation Based on Damage Mechanics

2013 ◽  
Vol 639-640 ◽  
pp. 1193-1199 ◽  
Author(s):  
Song Hua Tang ◽  
Ying She Luo ◽  
Shui Ping Yin ◽  
Yong Hong Li ◽  
Chao Chen ◽  
...  
Keyword(s):  
Temperature Field ◽  
Heat Conduction ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Concrete Slab ◽  
Failure Process ◽  
Strength Theory ◽  
Fire Response ◽  
Damage Evolution Equation ◽  
Damage And Failure

Damage mechanics is introduced into the fire response calculation of the concrete structure. The damage mechanics equations for fire response calculation are established. They are the damage evolution equation based on “residual strength” theory, heat conduction equations, and elastic mechanical equations. The fire response calculation of a concrete slab under external load and fire is shown. ANSYS is selected for calculating. The temperature field and stress field are obtained, the damage and failure process are described using the technique of killing or activating elements in ANSYS, and the fire resistance of the slab is obtained.

scholarly journals Particle jet impact deep-rock in rotary drilling: Failure process and lab experiment

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250588
Author(s):  
Tiancheng Fang ◽  
Fushen Ren ◽  
Baojin Wang ◽  
Jianxun Cheng ◽  
Hanxu Liu
Keyword(s):  
Damage Evolution ◽  
Failure Process ◽  
Damage Model ◽  
Engineering Application ◽  
Rock Breaking ◽  
Drilling Speed ◽  
Rotary Drilling ◽  
Rock Stratum ◽  
Technical Problems ◽  
Jet Impact

Aimed at the technical problems of low drilling speed and difficult rock-breaking in deep-well and hard rock-stratum, particle waterjet coupled impact rock-breaking technology in rotary drilling is put forward in this paper. Firstly, the working principle of particle jet impact rock-breaking in rotary drilling was introduced, and the acceleration model of particle jet and the damage model of rock were established. The acceleration mechanism of particles and dynamic damage evolution process of rock under particle jet were studied, which showed that the broken pit and rock damage would increase with time gone on, and damage evolution of rock presented the radial expansion. Then, experimental device of particle jet coupled impact rock-breaking in rotary state was developed, and the effect of jet parameters on penetration depth and failure volume was analyzed with comparison of la experiment and numerical simulation. The results showed that drilling speed with particle jet impact is twice that of conventional drilling, and combination nozzles layout of impact angle with 8°and 20° can achieve rock-drilled rapidly, which also demonstrated the correctness of simulation method. The device development and the rock-breaking results analysis would be of great value for engineering application.

scholarly journals Study on Damage Constitutive Model of High-Concentration Cemented Backfill in Coal Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Baogui Yang ◽  
Haigang Yang
Keyword(s):  
Constitutive Model ◽  
Coal Mine ◽  
Damage Evolution ◽  
Triaxial Compression ◽  
Failure Process ◽  
Model Parameters ◽  
High Concentration ◽  
Deformation And Failure ◽  
Cemented Backfill ◽  
Damage Constitutive Model

In order to construct the damage constitutive model (DCM) of high-concentration cemented backfill (HCCB) in coal mine, the generalized Hoek-Brown strength criterion was used as the failure criterion. For the difference of theoretical derivation of constitutive relation, a new DCM based on residual strength was proposed. Combined with the conventional triaxial compression test, the correctness and rationality of the DCM were verified. The damage evolution characteristics of HCCB were analyzed, and the physical meaning of model parameters was clarified. The results show that (a) the theoretical curves of stress-strain relation are in good agreement with its experimental curves, which means DCM can simulate the deformation and failure process of HCCB. (b) The damage evolution curve of HCCB is S -shaped. To some extent, the confining pressure can inhibit the development of damage. (c) The parameter F 0 reflects the position of the peak point of the DCM, and parameter n is the slope of the straight line segment in the postpeak strain softening stage, which are, respectively, used to characterize the strength level and brittleness of HCCB. The establishment of DCM of HCCB is helpful to reveal its deformation and failure mechanism and provides theoretical basis for its strength design.

Experimental and numerical analysis of shear process of a high particle content bonding material

2021 ◽  
pp. 1-26
Author(s):  
Yizhan Yang ◽  
Jiliang Li ◽  
Jiankang Chen
Keyword(s):  
Shear Band ◽  
Damage Evolution ◽  
Shear Failure ◽  
Mechanical Response ◽  
Failure Process ◽  
Compressive Loading ◽  
Adjustment Process ◽  
Particle Content ◽  
High Particle ◽  
Shear Process

Abstract In this study, polymer-bonded sugar (PBS) is used as an substitute material for polymer-bonded explosive (PBX), and the shear failure process of PBS under compressive loading. Firstly, the shear failure process of PBS was analyzed by a series of experiments, and it was found that the shear band appearing on the surface of the specimen was not symmetrical. Further theory analysis showed that it was triggered by the evolution of asymmetric damage caused by internal defects in the material. In addition, through investigating the distribution of experimental scatters, we found that the material undergoes a relatively long period of internal microstructure adjustment before shear failure occurs, this adjustment will undoubtedly affect the evolution of shear band. More importantly, a data density method was used to quantify the adjustment process. Finally, by using finite element simulation, the effects of matrix-particle-interface strength on the mechanical response or damage evolution of the PBS were thoroughly examined. This research has reference significance for understanding the damage evolution process of high particle content composite materials.

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