scholarly journals Microstructure evolution of AA5052 joint failure process and mechanical performance after reconditioning with tubular rivet

2021 ◽  
Vol 31 (11) ◽  
pp. 3380-3393
Author(s):  
Xiao-qiang REN ◽  
Chao CHEN ◽  
Xiang-kun RAN ◽  
Yu-xiang LI ◽  
Xin-gang ZHANG
Keyword(s):  
Microstructure Evolution ◽  
Mechanical Performance ◽  
Failure Process ◽  
Joint Failure

Acoustic Emission Characteristics of Rock Failure under Uniaxial Loading

2011 ◽  
Vol 378-379 ◽  
pp. 43-46 ◽  
Author(s):  
Tao Xie ◽  
Qing Hui Jiang ◽  
Rui Chen ◽  
Wei Zhang
Keyword(s):  
Acoustic Emission ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Progressive Failure ◽  
Failure Process ◽  
Testing Machine ◽  
Rock Failure ◽  
Rock Failure Process ◽  
State Variation ◽  
Acoustic Emission Test

With RMT-150C rock testing machine and AEWIN E1.86 DISP acoustic emission system applied, the acoustic emission test was accomplished with two kinds of rock samples including marble and granite under uniaxial compression. Cyclic loading and continuous loading were used through the experiment, and the mechanical performance and acoustic emission (AE) characteristics were obtained during the process of rock progressive failure. Details related to the relationship between amount of AE and stress-strain was given in this paper. A comparison between marble and granite was made as well following the general AE law, on the basis of which, the failure mechanism of rock mass was investigated. Finally, some conclusions can be summarized as follows:(1) AE activity features are different with stress state variation in rock failure process;(2) loading patterns make a direct impact on the failure process thereby affecting AE activities;(3)AE activities are various basing on the different types of rocks, structures and failure modes.

scholarly journals Effect of homogenization on microstructure evolution and mechanical properties of aged Mg-Nd-Sm-Zn-Zr alloy

2021 ◽  
Author(s):  
Tao Ma ◽  
Sicong Zhao ◽  
Liping Wang ◽  
Zhiwei Wang ◽  
Erjun Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Microstructure Evolution ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Homogenization Temperature ◽  
Aged Alloy ◽  
Homogenization Treatment ◽  
Β Phase ◽  
Average Grain Size

Abstract As an indispensable pre-treatment for aging, homogenization treatment has a significant effect on precipitation behavior of the Mg-RE alloys. Herein, the influence of homogenization temperature on the microstructure evolution and mechanical performance of a novel Mg-2.0Nd-2.0Sm-0.4Zn-0.4Zr (wt.%) alloy has been studied systematically. The results indicated that the as-cast alloy was mainly composed of α-Mg matrix, β-Mg12(Nd,Sm,Zn) phase and Zr-containing particles. Upon increasing the homogenization temperature from 500 oC to 525 oC for 8 h, the average grain size of as-homogenized alloy increased from 76 μm to 156 μm, and the content of β phase decreased gradually. It was worth noting that the homogenization temperature exceeded 515 oC, the β phase at the grain boundaries was completely dissolved. After aging at 200 oC for 18 h, numerous of plate-like β' phases were observed in α-Mg matrix. The rise in homogenization temperature was conducive to nucleation and growth of the β' phase. However, excessive homogenization temperature significantly coarsened grain size. The aged alloy under homogenization treatment at 515 oC for 8 h achieved optimal mechanical properties. The values of ultimate tensile strength, yield strength and elongation were 261 MPa, 154 MPa and 5.8 %, respectively. The fracture mode of the aged alloy mainly exhibited a typical transgranular cleavage fracture.

Validation of a Finite Element Model of the Mechanical Performance of Surgical Knots of Varying Topology

2018 ◽  
Author(s):  
Arz Y. Qwam Alden ◽  
Andrew G. Geeslin ◽  
Peter A. Gustafson
Keyword(s):  
Finite Element ◽  
Laboratory Tests ◽  
Computational Models ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Failure Process ◽  
Finite Element Models ◽  
Stress Concentrations ◽  
Surgical Suture ◽  
Knot Security

Background: Knot tying is considered a basic surgical skill, however, there is no consensus on the best technique. Suture breakage and slippage are failure modes during surgical repair and are related to stress concentrations which cannot be easily established with physical testing. Few computational models exist that describe the effect of knot topology on the failure mechanism. The purpose of this study was to implement the finite element method to analyze the mechanical behavior of surgical sutures according to number of throws and to validate the model against experiments. Methods: Experiments and models of monofilament and multifilament sutures were conducted. Multiple throw knots were tested to failure in a laboratory setting and with corresponding finite element models. Gross loads were compared when the knot reached a localized material yield stress in the model or when failure occurred in laboratory tests that have the same suture topology. Results: The results of laboratory tests and corresponding finite element models of single throw knots were compared and found to be well correlated and consistent with existing literature in strength prediction and failure location. Moreover, single throw knots have reduced failure strengths relative to non-knotted suture approximately by 120 N for both monofilament and multifilament sutures, respectively. Clinical Relevance: This paper describes a model which can describe the initial failure process leading to knot failure. In addition, the model can evaluate the effect of knot topology on the mechanics of surgical suture. Numerically, no assessment has been completed of knot security (i.e., how likely the knot is to untie), therefore, clinical recommendations are premature. In the future, the results may provide a framework for choosing the suture and knot types for soft tissue repairs.

Research on the Nonlinear Performance of the Pier under Horizontal Force

2014 ◽  
Vol 1030-1032 ◽  
pp. 1029-1032
Author(s):  
Wan Li Yang ◽  
Yu Cheng Fan ◽  
Jin Yan
Keyword(s):  
Significant Influence ◽  
Mechanical Performance ◽  
Failure Process ◽  
Material Nonlinearity ◽  
Horizontal Force ◽  
Construction Process ◽  
Construction Stage ◽  
Long Span ◽  
Element Program ◽  
Nonlinear Performance

Usually, a large horizontal force will be generated to the pier in the construction process, which may induce significant influence on the pier‘s safety, especially in the case of the bridges with high piers and long span. Some cracks ermerged in the foot part of a pier in the construction stage and a horizontal force was believed to have been load on it, hence its reliability was douted.The pier was simulated with virtual laminated element program, and its mechanical performance under a horizontal force was calculated with both geometrical and material nonlinearity are considerd, thus its whole loading and failure process was illustrated and the pier’s safety was assessed.

scholarly journals Experimental and Numerical Investigation on C/SiC Composite Z-Pinned/Bonded Hybrid Single-Lap Joints

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1130
Author(s):  
Yao Wang ◽  
Xiaodong Wang ◽  
Zhidong Guan ◽  
Jifeng Xu ◽  
Xia Guo
Keyword(s):  
Failure Mechanism ◽  
Composite Structures ◽  
Mechanical Performance ◽  
Failure Process ◽  
Three Dimensional ◽  
Discrete Distribution ◽  
Lap Joints ◽  
Single Lap Joints ◽  
Load Peak ◽  
Two Peaks

Z-pinned/bonded joints are great potential connection components that have been used in the 2D C/SiC composite structures; however, the hybrid joints present complex failure mechanism considering the secondary deposited SiC matrix in the clearance. Therefore, the mechanical performance and failure mechanism of the joints are investigated through experimental and numerical methods in this paper. Experiment results show that two peaks exist in the load–displacement curves. The first load peak is 2891–4172 N with the corresponding displacement of 0.10–0.15 mm, and the second load peak is 2670–2919 N with the corresponding displacement of 0.21–0.25 mm. Besides that, the secondary deposited SiC matrix exhibits discrete distribution, and it has significant effects on the failure mechanism. Validated by experimental data, the proposed three-dimensional numerical model based on modified Hashin’s criterion and fastener element can predict the mechanical performance and failure process. The numerical results indicate that the first load peak is dominated by the deposited SiC matrix near the edge, while the second peak is dominated by the z-pin and the SiC matrix near the z-pin. Moreover, the effects of the deposited SiC matrix’s strength and distribution are discussed, which is meaningful to the optimal design of C/SiC composite z-pinned/bonded hybrid single-lap joints.

scholarly journals Direct Shear Behavior of Nanometer Magnesia Reinforced Cement Soil with 28d Age

2014 ◽  
Vol 8 (1) ◽  
pp. 509-513
Author(s):  
Shuai Zhang ◽  
Wei Wang ◽  
Xinjiang Song ◽  
Xuchao Chi ◽  
Tinghao Lu
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Mechanical Performance ◽  
Failure Process ◽  
Particle Interaction ◽  
Friction Angle ◽  
Mixing Ratio ◽  
Convex Shape ◽  
Mixing Ratios ◽  
Cement Soil

In order to properly understand the modification effects of nanometer magnesia additive on cement soil’s mechanical performance, a consolidated quick shear laboratory test on nano-magnesium-modified cement-soil (NmCS) sample with different mixing ratio at 28-day age was conducted. Eight kinds’ of nanometer magnesia additives with mixing ratios ranging from 0% to 3% were designed to be used in the test. The result shows that: (1) shear stressdisplacement curves of all samples consisted of three distinct stages with brittle failure. Moreover, (2) as the nanometer magnesia mixing ratio increased, the NmCS shear strength also showed an increase at first, followed by a decrease, and the shear strength reached the maximum with the mixing ratio of 1%. (3)In addition, both the friction angle and cohesive force were fluctuating and had a concave and convex shape respectively and (4) with greater deformation resistance, the shear displacement of NmCS was significantly less than the ordinary cement soil in the shear failure process. Finally, according to the test results, the micro-mechanism of NmCS mechanical performance was analyzed from the perspective of cement hydration and particle interaction.

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