Utilization of the relative rigidity concept to predict the failure of pipe systems under explosive loads

1996 ◽  
Vol 23 (1) ◽  
pp. 107-116
Author(s):  
A. O. Abd El Halim ◽  
D. T. Lau ◽  
A. G. Razaqpur ◽  
J. A. Winterink
Keyword(s):  
Failure Modes ◽  
Geometric Distortion ◽  
Failure Patterns ◽  
Numerical Studies ◽  
Relative Rigidity ◽  
Theoretical Predictions ◽  
Explosive Failure ◽  
Pipe Systems ◽  
Soil Foundation ◽  
Interaction Stress

The interaction between loading plates and supporting structures is very much dependent upon the relative rigidity of the system. This paper first illustrates how an indiscriminate application of the relative rigidity concept can lead to erroneous conclusions in such systems. The paper then applies the concept to explain reported observed failure modes in pipe systems under explosive loads. Numerical studies are presented which simulate the behaviour of square pipe systems under static and explosive loads using the concept of relative rigidity in conjunction with the finite element method. The results of the analysis confirm the hypothesis of the relative rigidity concept. Experimental verification of the theoretical predictions and numerical modelling results are obtained by simulating the explosive failure patterns in simple freezing experiments. The analysis presented in this paper demonstrates the importance of the concept of relative rigidity for explaining certain kinds of observed failure and fracture phenomena. Key words: cracks, explosives, geometric distortion, load transmitting plate, pipes, relative rigidity, soil – foundation interaction, stress waves.

scholarly journals Study on Impact Damage and Energy Dissipation of Coal Rock Exposed to High Temperatures

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Tu-bing Yin ◽  
Kang Peng ◽  
Liang Wang ◽  
Pin Wang ◽  
Xu-yan Yin ◽  
...  
Keyword(s):  
High Temperatures ◽  
Failure Modes ◽  
Split Hopkinson Pressure Bar ◽  
Impact Damage ◽  
Time History ◽  
Hopkinson Pressure Bar ◽  
Absorbed Energy ◽  
Failure Patterns ◽  
Temperature Conditions ◽  
Coal Rock

The dynamic failure characteristics of coal rock exposed to high temperatures were studied by using a split Hopkinson pressure bar (SHPB) system. The relationship between energy and time history under different temperature conditions was obtained. The energy evolution and the failure modes of specimens were analyzed. Results are as follows: during the test, more than 60% of the incident energy was not involved in the breaking of the sample, while it was reflected back. With the increase of temperature, the reflected energy increased continuously; transmitted and absorbed energy showed an opposite variation. At the temperature of 25 to 100°C, the absorbed energy was less than that transmitted, while this phenomenon was opposite after 100°C. The values of specific energy absorption (SEA) were distributed at 0.04 to 0.1 J·cm−3, and its evolution with temperature could be divided into four different stages. Under different temperature conditions, the failure modes and the broken blocks of the samples were obviously different, combining with the variation of microstructure characteristics of coal at high temperatures; the physical mechanism of damage and failure patterns of coal rock are explained from the viewpoint of energy.

Fatigue Failure Modes in Self-Piercing Riveted Aluminium Alloy Joints

Volume 3 ◽  
2004 ◽  
Author(s):  
L. Han ◽  
K. Young ◽  
R. Hewitt ◽  
A. Chrysanthou ◽  
J. M. O’Sullivan
Keyword(s):  
Aluminium Alloy ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Surface Condition ◽  
Fatigue Behaviour ◽  
Alloy Sheet ◽  
Static Tests ◽  
Failure Patterns ◽  
Interfacial Conditions ◽  
Sheet Surface

Self-piercing riveting, as an alternative joining method to spot-welding, has attracted considerable interest from the automotive industry and has been widely used in aluminium intensive vehicles. One of the important factors that need to be considered is the effect of cyclic loading in service, leading to possible fatigue failure. The previous work reported in the public domain on the behaviour of self-piercing rivets has mainly focused on static tests. The work which is reported in this paper is concerned with the fatigue behaviour of single-rivet joints, joining two 2mm 5754 aluminium alloy sheets. The investigation also examined the effect of interfacial conditions on the fatigue behaviour. A number of fatigue failure mechanisms were observed based on rivet fracture, sheet fracture and combinations of these. The investigation has shown that they were dependent on the applied load and the sheet surface condition. Three-parameter Weibull analysis, using Reliasoft Weibull ++5.0 software, was conducted to analyse the experimental results. The analysis enabled the prediction of early-type failure (infant mortality failure) and wear-out failure patterns depending on the condition of the self-piercing riveted joints and the alloy sheet surface.

Failure Modes of Tapered Suction Caissons Under Vertical Pull-Out Loads

2007 ◽  
Author(s):  
Mahmood Nabipour ◽  
Mostafa Zeinoddini ◽  
Mahmood R. Abdi
Keyword(s):  
Failure Modes ◽  
Numerical Approach ◽  
Local Failure ◽  
Superior Performance ◽  
Soil Plug ◽  
Pull Out ◽  
Modes Of Failure ◽  
Numerical Studies ◽  
Second Mode ◽  
Suction Caissons

The pull-out performance of conventional upright suction caissons has been investigated by different researchers. However, no attention has been formerly paid to tapered suction caissons. Some numerical studies already conducted by the authors demonstrated that tapered caissons exhibit pull-out capacities well above than that from their corresponding upright caissons. This paper deals with different failure mechanisms of tapered suction caissons and discusses some reason for their superior performance. A numerical approach has been used and different combinations of caisson types/ soil categories have been examined. With tapered suction caissons two different modes of failure have been discerned. The first mode has been noticed to develop in weak clays and sands under drained conditions. This mode corresponds to a shear sliding failure in the soil plug along the caisson’s interior wall. Concurrently a soil wedge is formed in the soil body adjacent to the caisson. The second mode of failure has been observed in higher strength drained clays and undrained clays and sands. With this failure mode a local failure at the bottom of the soil plug has been noticed to happen. At the same time the failure is extended to the lower surfaces of a soil wedge outside of the caisson. The detached soil plug accompanies the caisson in its movement upward following the local failure.

Experimental, theoretical, and numerical studies on the response of square plates subjected to blast loading

2011 ◽  
Vol 46 (8) ◽  
pp. 805-816 ◽  
Author(s):  
K H Safari ◽  
J Zamani ◽  
S M R Khalili ◽  
S Jalili
Keyword(s):  
Blast Wave ◽  
Failure Modes ◽  
Scaling Law ◽  
Blast Loading ◽  
Material Failure ◽  
Perfectly Plastic ◽  
Numerical Studies ◽  
Fluid Solid Interaction ◽  
Interaction Problem ◽  
Dynamic Plasticity

This article presents the results of experimental and analytical studies on the response of steel and aluminium square plates with different thicknesses subjected to blast loading. Based on the blast wave details and the scaling law for explosions, a method of determining the blast load is proposed in which ballistic pendulums do not need to be utilized for obtaining the blast wave impulses. The loads applied to the plates are assumed to be the quasi-exponential pressure pulses, which are the same as the explosion overpressures. The theoretical solutions are presented using a rigid, perfectly plastic idealization and are exact within the context of dynamic plasticity. The dynamic energy imparted to structures can cause material failure. The presented investigation considers such a failure for fully clamped plates subjected to a blast loading idealized as an initial velocity distributed uniformly throughout the area. The predicted deflections and general failure modes of the plates are presented and compared with experimental results. Moreover, a numerical simulation is carried out by modelling an FSI (fluid–solid interaction) problem. Results are compared with each other and a better agreement between numerical results with experimental ones is observed.

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.

Failure Modes of CFRP Flexural Strengthened Steel I-Beams

2011 ◽  
Vol 471-472 ◽  
pp. 590-595 ◽  
Author(s):  
Kambiz Narmashiri ◽  
Mohd Zamin Jumaat ◽  
Nor Hafizah Ramli Sulong
Keyword(s):  
Failure Modes ◽  
Steel Structures ◽  
Fiber Reinforced Polymer ◽  
Bending Test ◽  
Steel Beams ◽  
Numerical Studies ◽  
Reinforced Polymer ◽  
Cfrp Plate ◽  
Critical Regions ◽  
Incremental Loading

This paper presents the experimental and numerical studies on the flexural strengthened steel I-beams by using Carbon Fiber Reinforced Polymer (CFRP) strips. Nowadays, strengthening existing steel structures by using CFRP has been widely interested. One of the common usages of CFRP to strengthen steel beams is the flexural upgrading. In this case, CFRP strips are pasted on the tensile flange to improve flexural behaviors. The problems that are frequently reported for CFRP strengthened steel beams are the debonding, delaminating (peeling), and splitting. Identification these failure modes are essential to provide an appropriate level of safety for strengthened steel beams. To investigate the CFRP failure modes, four strengthened steel I-beams were chosen. The CFRP plates with different thicknesses in single and double (splice) layers were used. Both experimental test (four-points bending test) and numerical simulation (full 3D simulation with ANSYS) were employed. The incremental loading was applied until failure while deformations in the critical regions were recorded. The results reveal that for the CFRP flexural strengthened steel beams the following failure modes occurred: (a) debonding at the CFRP plate tips, (b) debonding below point loads, (c) delaminating at the ends of CFRP plate, and (d) splitting below point loads. The sequence of failure modes depended on the specifications of CFRP plate. Some recommendations are provided to overcome/retard these failures.

scholarly journals Experimental Study of Reinforcing Broken Gangues by Colloid Cement Slurry

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xin Lyu ◽  
Ke Yang ◽  
Qiang Fu ◽  
Zhen Wei ◽  
Shuai Liu
Keyword(s):  
Failure Mode ◽  
Cement Paste ◽  
Failure Modes ◽  
Axial Strain ◽  
Optimal Choice ◽  
Strengthening Effect ◽  
Reinforcement Effect ◽  
Cement Slurry ◽  
Load Bearing ◽  
Failure Patterns

Studies on jet grouting materials mainly focus on the aggregates in cement or the environment where they are maintained and rarely deal with the cohesiveness, reinforcement load-bearing characteristics, and surface spalling. In this study, cement slurries with different colloid contents were prepared to explore the characteristics and reinforcement effect of broken gangues. These were then subjected to mechanical testing to measure the strength and axial strain performance, and the failure modes and failure patterns were discussed. The results indicated that the colloid component has a significant strengthening effect on the early strength of the samples. As the age increased, the sample axial strain and elastic modulus of the colloid cement paste increased as the colloid component provides viscoelasticity when it resists deformation. The sample strength of cement paste decreases after the addition of broken gangue while the strength of class E samples increases significantly during each age. The cement paste sample showed penetrating splitting failure, the colloidal component effectively controlled the peeling of sample surface, and the failure mode after adding gangue was relatively complicated. The instability modes of the samples are divided into dispersed load-bearing instability and cumulative load-bearing instability, and the content of colloid components affects the failure mode of the samples. A colloid component proportion of 23.33% is the optimal choice, which has an obvious reinforcement effect on the broken gangue.

scholarly journals Topological edge states of anyon pairs emulated in electric circuits

2021 ◽  
Vol 2015 (1) ◽  
pp. 012127
Author(s):  
A D Rozenblit ◽  
N A Olekhno ◽  
A A Dmitriev ◽  
P S Seregin ◽  
M A Gorlach
Keyword(s):  
Electric Circuit ◽  
Quantum Statistics ◽  
Edge States ◽  
Fractional Quantum ◽  
Electric Circuits ◽  
Numerical Studies ◽  
Topological Quantum ◽  
Theoretical Predictions ◽  
Topological States ◽  
Geometrical Imperfections

Abstract Recent advances in two-particle topological quantum states demonstrate resilience to geometrical imperfections and hold perspectives for robust quantum computations. In this context, particles with fractional quantum statistics, the so-called anyons, attract especial attention. In particular, topological edge states of anyon pairs in one-dimensional chains of coupled cavities were recently predicted to demonstrate localization at one or another edge of the array depending on details of the quantum statistics. In this paper, propose an equivalent electric circuit serving as a classical emulator of such topological states. Detailed numerical studies of resonances in the circuit fully support theoretical predictions, pointing towards future experimental realizations of anyonic states analogs in electrical circuits.

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