Combined numerical and experimental studies on the dynamic and quasi-static failure modes of brittle rock

2021 ◽  
Vol 148 ◽  
pp. 104957
Author(s):  
Chunjiang Zou ◽  
Huanqiang Li
Keyword(s):  
Failure Modes ◽  
Experimental Studies ◽  
Brittle Rock ◽  
Static Failure

Experimental Studies on Axially Loaded Concrete Columns Confined by Different Materials

2008 ◽  
Vol 400-402 ◽  
pp. 513-518 ◽  
Author(s):  
Yong Chang Guo ◽  
Pei Yan Huang ◽  
Yang Yang ◽  
Li Juan Li
Keyword(s):  
Bearing Capacity ◽  
Glass Fiber ◽  
Failure Modes ◽  
Experimental Studies ◽  
Concrete Columns ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Advantages And Disadvantages ◽  
Axially Loaded ◽  
Normal Strength

The improvement of the load carrying capacity of concrete columns under a triaxial compressive stress results from the strain restriction. Under a triaxial stress state, the capacity of the deformation of concrete is greatly decreased with the increase of the side compression. Therefore, confining the deformation in the lateral orientation is an effective way to improve the strength and ductility of concrete columns. This paper carried out an experimental investigation on axially loaded normal strength concrete columns confined by 10 different types of materials, including steel tube, glass fiber confined steel tube (GFRP), PVC tube, carbon fiber confined PVC tube (CFRP), glass fiber confined PVC tube (GFRP), CFRP, GFRP, polyethylene (PE), PE hybrid CFRP and PE hybrid GFRP. The deformation, macroscopical deformation characters, failure mechanism and failure modes are studied in this paper. The ultimate bearing capacity of these 10 types of confined concrete columns and the influences of the confining materials on the ultimate bearing capacity are obtained. The advantages and disadvantages of these 10 types of confining methods are compared.

Experimental investigation and modeling of dynamic thermomechanical behavior of 4-harness satin weave carbon/epoxy composites

2017 ◽  
Vol 31 (9) ◽  
pp. 1181-1203 ◽  
Author(s):  
Xueyao Hu ◽  
Hui Guo ◽  
Weiguo Guo ◽  
Feng Xu ◽  
Longyang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Composite Laminates ◽  
Failure Modes ◽  
Shear Failure ◽  
Experimental Studies ◽  
Temperature Shift ◽  
Thermomechanical Coupling ◽  
Longitudinal Splitting ◽  
Wide Range

Theoretical and experimental studies on the compressive mechanical behavior of 4-harness satin weave carbon/epoxy composite laminates under in-plane loading are conducted over the temperature range of 298–473 K and the strain rate range of 0.001–1700/s in this article. The stress–strain curves of 4-harness satin weave composites are obtained at different strain rates and temperatures, and key mechanical properties of the material are determined. The deformation mechanism and failure morphology of the samples are observed and analyzed by scanning electron microscope (SEM) micrographs. The results show that the uniaxial compressive mechanical properties of 4-harness satin weave composites are strongly dependent on the temperature but are weakly sensitive to strain rate. The peak stress and elastic modulus of the material have the trend of decrease with the increasing of temperature, and the decreasing trend can be expressed as the functional relationship of temperature shift factor. In addition, SEM observations show that the quasi-static failure mode of 4-harness satin weave composites is shear failure along the diagonal lines of the specimens, while the dynamic failure modes of the material are multiple delaminations and longitudinal splitting, and with the increasing of temperature, its longitudinal splitting is more serious, but the delamination is relatively reduced. A constitutive model with thermomechanical coupling effects is proposed based on the experimental results and the increment theory of elastic–plastic mechanics. The experimental verification and numerical analysis show that the model is shown to be able to predict the finite deformation behavior of 4-harness satin weave composites over a wide range of temperatures.

scholarly journals Numerical and experimental studies on wrinkling control methods of sheet metal part with high curvature and large flange in rubber forming

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988378
Author(s):  
Lei Chen ◽  
Ying Bai ◽  
Zhengyi Jiang ◽  
Huiqin Chen ◽  
Can Wu ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Failure Modes ◽  
Optimal Parameter ◽  
Experimental Studies ◽  
Element Model ◽  
Resistance Force ◽  
Forming Process ◽  
Complex Deformation ◽  
Metal Forming Process ◽  
Rubber Forming

Wrinkling is one of the main failure modes in sheet metal forming process and may lead to assembly problems of the parts. Control of wrinkling is difficult due to the complex deformation behavior of the sheet metal. A finite element model for side blankholder method to control wrinkling was established and used for the simulation. Trials and simulations were conducted to analyze the parameters of wrinkling characteristics. Results show that with the increase in the angle of the side blankholder, the resistance force of the side blankholder decreases. The blank length on the side blankholder should be small enough. The fillet radius of the side blankholder should be large enough to reduce the deformation. The bottom gap between the die and the side blankholder cannot be too large because the support of the blank will decrease in the forming process. In order to verify the simulation results, three blank lengths (20, 15, and 5 mm) over the side blankholder were used in the experiment. The results of the comparison tests testify the reliability of the simulation. The optimal parameter of the blank length is 5 mm. A new clamp method was designed for wrinkling control to overcome the shortcomings of the side blankholder method. The precision of the part met the requirement using soft rubber and two layers of rubber plates.

Experimental studies of a typical sprinkler piping system in hospitals

2016 ◽  
Vol 49 (1) ◽  
pp. 1-12
Author(s):  
Zhen-Yu Lin ◽  
Fan-Ru Lin ◽  
Juin-Fu Chai ◽  
Kuo-Chun Chang
Keyword(s):  
Failure Modes ◽  
Experimental Studies ◽  
Hysteresis Loops ◽  
Research Programme ◽  
Shaking Table ◽  
Piping System ◽  
Improvement Strategy ◽  
Flexible Pipes ◽  
Piping Systems ◽  
Cyclic Loading Tests

Based on the issue of life safety and immediate needs of emergency medical services provided by hospitals after strong earthquakes, this paper aims to introduce a research programme on assessment and improvement strategies for a typical configuration of sprinkler piping systems in hospitals. The study involved component tests and subsystem tests. Cyclic loading tests were conducted to investigate the inelastic behaviour of components including concrete anchorages, screwed fittings of small-bore pipes and couplings. Parts of a horizontal piping system of a seismic damaged sprinkler piping system were tested using shaking table tests. Furthermore, horizontal piping subsystems with seismic resistant devices such as braces, flexible pipes and couplings were also tested. The test results showed that the main cause of damage was the poor capacity of a screwed fitting of the small-bore tee branch. The optimum improvement strategy to achieve a higher nonstructural performance level for the horizontal piping subsystem is to strengthen the main pipe with braces and decrease moment demands on the tee branch by the use of flexible pipes. The hysteresis loops and failure modes of components were further discussed and will be used to conduct numerical analysis of sprinkler piping systems in future studies.

Glulam rivet connections under eccentric loading

1987 ◽  
Vol 14 (5) ◽  
pp. 621-630 ◽  
Author(s):  
Erol Karacabeyli ◽  
Ricardo O. Foschi
Keyword(s):  
Failure Modes ◽  
Experimental Studies ◽  
Design Guidelines ◽  
Bearing Failure ◽  
Element Analysis ◽  
Theoretical Predictions ◽  
Failure Loads ◽  
Fracture Theory ◽  
Timber Engineering ◽  
Type Of Failure

Results from theoretical and experimental studies on the strength of glulam rivet connections under eccentric loading are presented. Two failure modes are studied: (1) rivet yielding in bending with simultaneous bearing failure of the wood under the rivet's shank and (2) wood failure around the rivet cluster. The latter is studied using brittle fracture theory and a finite element analysis of the stress distribution in the wood around the rivets.Experimental results are shown to compare well with theoretical predictions for failure loads and type of failure, and design guidelines are proposed. Key words: fasteners, wood connectors, glued-laminated, nails, timber engineering.

Multiscale Experimental and Computational Investigation of Cortical Bone Fracture

2013 ◽  
Author(s):  
E. M. Feerick ◽  
J. P. McGarry
Keyword(s):  
Cortical Bone ◽  
Bone Fracture ◽  
Failure Modes ◽  
Experimental Studies ◽  
Explicit Representation ◽  
Computational Investigation ◽  
Crack Trajectory ◽  
Macro Scale ◽  
Isotropic Damage ◽  
Geometric Representations

Previous experimental studies of cortical bone have investigated cortical bone fracture toughness and crack trajectory as a function of microstructural alignment of osteons [1,2]. The dependence of osteon orientation on screw pullout force and crack propagation trajectory during screw pullout has been demonstrated previously by Feerick and McGarry (2012) [3]. The alternate failure modes for longitudinal and transverse screw pullout observed in the latter study are shown in Figure 1. Using an isotropic damage criterion with crack growth was simulated using an element deletion technique. An explicit representation of cortical bone microstructure was required to replicate experimental observations. The use of such a computational scheme for 3D macro-scale applications is not viable given the requirement of explicit representation of the microstructure. Other computational studies of cortical bone have also developed geometric representations of the microstructure of cortical bone to simulate the fracture and establish crack trajectories [4]. Again, upscaling these detailed microstructural geometries in 3D macroscale simulations of fracture would currently be computationally unfeasible.

Aging Effect on Corrosion Damage Evolution Behavior of Fuse-Head Used for Electric Explosive Device

2012 ◽  
Vol 166-169 ◽  
pp. 1883-1886
Author(s):  
You Hong Zhang ◽  
Qian Zhang ◽  
Xin Long Chang ◽  
Chun Guo Yue ◽  
Shi Ying Zhang ◽  
...  
Keyword(s):  
Damage Evolution ◽  
Failure Modes ◽  
Experimental Studies ◽  
Corrosion Damage ◽  
Aging Effect ◽  
Factors Affecting ◽  
Temperature And Humidity ◽  
Explosive Device ◽  
Effects Of Temperature ◽  
Evolution Behavior

Degradation of mechanical properties of electric explosive device fuse-head was serious in different temperature and humidity environments. The objective of this study was to examine the effects of temperature and humidity aging on the damage evolution behavior of fuse-head used for electric explosive device. In this paper, the experimental studies were presented to appreciate the influence of humidity and temperature on the corrosion damage and firing of electric explosive device. The damage mechanisms and failure modes were determined through nondestructive evaluation. The explosive broken and corrosion damage on lead induced by temperature and humidity aging were the main factors affecting the firing probability. At last, the evolution rule of corrosion damage in the environment of different relative humidity and temperature was discussed.

scholarly journals Theoretical and Experimental Studies of Two-Span Reinforced Concrete Deep Beams and Comparisons with Strut-and-Tie Method

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Mahsa Zargarian ◽  
Alireza Rahai
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Experimental Studies ◽  
Nonlinear Finite Element ◽  
Shear Mode ◽  
Design Codes ◽  
Load Prediction ◽  
Deep Beams ◽  
Strut And Tie ◽  
Truss Model

Regarding the complicated behavior of continuous deep beams, a research program including three parts was conducted. First part: three continuous concrete deep beams with different shear span-to-depth ratios (a/h) were tested. The effects of varying a/h ratio on ultimate strength and failure modes were investigated. Second part: the nonlinear finite element (FE) analyses were performed to simulate the experimental specimens and 21 large-scale continuous deep beams. The main parameters investigated were a/h ratio from 0.33 to 2 and f c ′ considered 40 MPa, 60 MPa, and 80 MPa. Third part: the strut-and-tie modeling of different design codes and indeterminate strut-tie method were studied for continuous deep beams. Regardless of the a/h ratio, all beam specimens failed in shear mode with main diagonal cracks. Although EC2 load prediction was conservative for all beam models, the ACI and CSA predictions for concrete deep beams with high compressive strength were unsafe. The indeterminate truss model showed closer results to FE analysis in comparison with ACI, EC2, and CSA strut-and-tie method.

scholarly journals Bonding Behaviors of GFRP/Steel Bonded Joints after Wet–Dry Cyclic and Hygrothermal Curing

2020 ◽  
Vol 10 (16) ◽  
pp. 5411
Author(s):  
Jie Liu ◽  
Tong Guo ◽  
Matthew H. Hebdon ◽  
Zhongxiang Liu ◽  
Libin Wang
Keyword(s):  
Fracture Energy ◽  
Failure Modes ◽  
Experimental Studies ◽  
Interfacial Fracture ◽  
Threshold Value ◽  
Mechanism Analysis ◽  
Cohesive Failure ◽  
Curing Conditions ◽  
Bonding Performance ◽  
Interfacial Fracture Energy

This paper presents the outcomes of a research program that tested and examined the behaviors of glass fiber-reinforced polymer (GFRP) bonded steel double-strap joints after being cured in a variety of harsh curing conditions. Nineteen specimens were manufactured, cured in an air environment (the reference specimen), treated with different wet–dry cyclic curing or hygrothermal pretreatment, and then tested under quasi-static loading. Based on the experimental studies, mixed failure modes, rather than the cohesive failure of the adhesive, were found in the harsh environmental cured specimens. Additionally, an approximately linear relationship of load–displacement curves was observed for all the GFRP/steel bonded specimens from which the tensile capacities and stiffness were discussed. By analyzing the strain development of the bonded specimens during quasi-static tensile testing, the fracture mechanism analysis focused on the threshold value of the strain curves for different cured specimens. Finally, based on the studies of interfacial fracture energy, Gf, the effects of harsh environmental curing were assessed. The results showed that the failure modes, joint tensile capacities, stiffness, and interfacial fracture energy Gf were highly dependent on the curing conditions, and a significant degradation of bonding performance could be introduced by the investigated harsh environments.

State-of-the-Art Review of Pressure Relief Valve Design, Testing and Modeling

1991 ◽  
Vol 113 (1) ◽  
pp. 46-54 ◽  
Author(s):  
P. M. Petherick ◽  
A. M. Birk
Keyword(s):  
Dynamic Characteristics ◽  
Nuclear Power ◽  
Literature Search ◽  
Failure Modes ◽  
State Of The Art ◽  
Experimental Studies ◽  
Pressure Relief Valve ◽  
Operating Characteristics ◽  
Relief Valve ◽  
Pressure Relief

It is well known that the response of a rail tank car to exterior heating (e.g., fire engulfment) is significantly affected by the operating characteristics of the pressure relief valve (PRV). If the valve jams or fails in some way, it can lead to a violent vessel rupture; therefore, PRV failure modes and mechanisms must be understood. This paper investigates the studies which have been conducted in the area of PRV technology. The original focus of the paper was to conduct a literature search to find the state-of-the-art for the PRV’s which are presently installed on railway tank cars, highway tankers, and stationary LPG storage vessels. When few papers were found which had concentrated on this particular topic, the authors continued the search by considering both the nuclear power and chemical processing industries, where similar technologies are found. The results of the literature search suggest that the PRV’s currently installed on tank cars and highway tankers are based on designs more than 30 yr old. Controlled fire tests and industry’s maintenance programs suggest that PRV’s could be improved. Most experimental studies of PRV’s have concentrated on flow visualization techniques and have not considered PRV dynamic characteristics. The lack of understanding of valve dynamic characteristics has slowed the development of improved PRV dynamic computer models.

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