Multiple Fracture of Beams Under Localized Impulsive Loading

1977 ◽  
Vol 44 (2) ◽  
pp. 259-263 ◽  
Author(s):  
J. D. Colton
Keyword(s):  
High Speed ◽  
Beam Theory ◽  
Impulsive Loading ◽  
Time Sequence ◽  
Bending Stress ◽  
Multiple Fracture ◽  
Fracture Patterns ◽  
Deformation And Fracture ◽  
Impulsive Loads ◽  
Framing Camera

The fracture patterns produced by localized impulsive loading on brittle beams and their dependence on the intensity and length of the load have been determined. Experiments were performed on effectively infinite beams loaded over a finite length with sheet explosive. The mechanisms, location, and time sequence of deformation and fracture were determined by posttest observation and by high-speed framing camera photographs. It was found experimentally that all fractures were initiated by bending stress and that the localized impulsive loading produced three different fracture patterns. The beam response was also predicted analytically by numerically integrating the characteristic equations of Timoshenko beam theory. It was found analytically that, depending on load length and intensity, a total of four fracture patterns, including the three observed experimentally, can be produced by localized impulsive loads.

Multiple Fracture of Plates Under Localized Impulsive Loading

1976 ◽  
Vol 43 (1) ◽  
pp. 33-38 ◽  
Author(s):  
J. D. Colton
Keyword(s):  
High Speed ◽  
Plate Theory ◽  
Impulsive Loading ◽  
Mindlin Plate ◽  
Strain Gages ◽  
Fracture Patterns ◽  
Deformation And Fracture ◽  
Impulsive Loads ◽  
Mindlin Plate Theory ◽  
Framing Camera

An investigation was performed to determine the fracture patterns produced by localized impulsive loading on brittle plates and their dependence on the intensity and area of the load. Experiments were performed on effectively infinite plates loaded over a finite area with sheet explosive. The mechanisms, location, and time sequence of deformation and fracture were determined by terminal observation, high-speed framing camera photographs, and strain gages. It was found that all fractures were initiated by bending stress; two different fracture patterns in plates were produced experimentally. The plate response was also predicted analytically by numerically integrating the characteristic equations of Mindlin plate theory. It was found analytically that, depending on loading intensity and duration, a total of five fracture patterns in plates, including both those observed experimentally, can be produced by localized impulsive loads.

Dynamic Fracture Process in Beams

1975 ◽  
Vol 42 (2) ◽  
pp. 435-439 ◽  
Author(s):  
J. D. Colton ◽  
G. Herrmann
Keyword(s):  
Dynamic Fracture ◽  
High Speed ◽  
Beam Theory ◽  
Bending Moment ◽  
Strain Gages ◽  
Second Stage ◽  
Deformation And Fracture ◽  
Initial Fracture ◽  
Beam Thickness ◽  
Stage Process

The relief waves created by the dynamic fracture of a brittle beam were determined. An experiment was conducted on an effectively infinite beam loaded over a finite area with sheet explosive. The time sequence of deformation and fracture was determined by terminal observation, high-speed framing camera photographs, and strain gages. Beam response was also predicted analytically by numerically integrating the characteristic equations of Timoshenko beam theory. Comparison of calculated and measured strains showed that the effect of an initial fracture in a beam at a location of pure bending can be approximated by a two-stage process that specifies how the bending moment at the fracture point is reduced to zero after fracture. In the first stage, the crack propagates to the neutral axis, and the stress distribution remains unchanged. In the second stage, the crack propagates through the remainder of the beam thickness while the stress continuously redistributes itself.

scholarly journals Response of Cylindrical Composite Structures Subjected to Underwater Impulsive Loading: Experimentations and Computations

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Tao Qu ◽  
Siddharth Avachat ◽  
Min Zhou
Keyword(s):  
Damage Evolution ◽  
Composite Structures ◽  
High Speed ◽  
Blast Resistance ◽  
Equal Mass ◽  
Impulsive Loading ◽  
Structural Deformation ◽  
Damage And Failure ◽  
Impulsive Loads ◽  
Thin Walled

The dynamic response of both thick-walled and thin-walled cylindrical composite structures subjected to underwater impulsive loads is analyzed. In the case of thick-walled structures, a novel experimental setup, the underwater shock loading simulator (USLS), is used to generate the impulsive loads. Deflection and core compression are characterized using high-speed digital imaging. The experiments are supported by fully dynamic numerical calculations which account for fluid–structure interactions (FSIs) and damage and failure mechanisms in the materials. The analysis focuses on the effect of varying structural attributes and material properties on load-carrying capacity, deformation mechanisms, and damage. Results show that cylindrical sandwich structures have superior blast-resistance than cylindrical monolithic structures of equal mass with only relatively minor increases in wall thickness. In the case of thin-walled structures, a unique computational framework based on a coupled Eulerian–Lagrangian (CEL) approach is developed to study the structural collapse and damage evolution under large impulsive loads which induces an implosion event. Simulations are carried out for a range of hydrostatic pressure and impulsive load intensity, with different loading configurations. Ply level stress analysis provides an insight on the stress–structural deformation–damage evolution relationship during the severe explosion-induced implosion event. The experiments, computations, and structure–performance relations developed in the current study offer approaches for improving the blast-mitigation capabilities of cylindrical composite sections in critical parts of marine structures, such as the keel, hull, and pipes.

scholarly journals Shock Tube as an Impulsive Application Device

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Soumya Ranjan Nanda ◽  
Sumit Agarwal ◽  
Vinayak Kulkarni ◽  
Niranjan Sahoo
Keyword(s):  
Heat Transfer ◽  
Shock Tube ◽  
High Speed ◽  
Force Measurement ◽  
Peak Load ◽  
Wave Force ◽  
Impulsive Loading ◽  
Force Balance ◽  
Test Model ◽  
Impulse Facility

Current investigations solely focus on application of an impulse facility in diverse area of high-speed aerodynamics and structural mechanics. Shock tube, the fundamental impulse facility, is specially designed and calibrated for present objectives. Force measurement experiments are performed on a hemispherical test model integrated with the stress wave force balance. Similar test model is considered for heat transfer measurements using coaxial thermocouple. Force and heat transfer experiments demonstrated that the strain gauge and thermocouple have lag time of 11.5 and 9 microseconds, respectively. Response time of these sensors in measuring the peak load is also measured successfully using shock tube facility. As an outcome, these sensors are found to be suitable for impulse testing. Lastly, the response of aluminum plates subjected to impulsive loading is analyzed by measuring the in-plane strain produced during deformation. Thus, possibility of forming tests in shock is also confirmed.

Explosively Driven Expansion and Fragmentation Behavior for Cylinders, Spheres and Rings of 304 Stainless Steel

2010 ◽  
Vol 638-642 ◽  
pp. 1035-1040 ◽  
Author(s):  
Tetsuyuki Hiroe ◽  
Kazuhito Fujiwara ◽  
Hidehiro Hata ◽  
Mitsuru Yamauchi ◽  
Kiyotaka Tsutsumi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
High Speed ◽  
Fracture Behavior ◽  
Copper Wire ◽  
304 Stainless Steel ◽  
Fragmentation Model ◽  
Fragmentation Behavior ◽  
Deformation And Fracture ◽  
Test Parameters ◽  
Fine Copper

Explosive loading techniques are applied to expand tubular cylinders, spherical shells and rings of 304 stainless steel to fragmentation, and the effects of wall thicknesses, explosive driver diameters and the constant proportionality of the in-plane biaxial stretching rates are investigated on the deformation and fracture behavior of three basic structures experimentally and numerically. In the cylinder tests, the driver is a column of high explosive PETN, inserted coaxially into the bore of a cylinder and initiated by exploding a fine wire bundle at the column axis using a discharge current from a high-voltage capacitor bank. In case of the ring tests, ring specimens are placed onto a single cylinder filled with the PETN as a expansion driver, and for sphere tests, specimens filled with the PETN are also initiated by exploding a fine copper wire line with small length located at the central point. Two types of experiments are conducted for every specimen and test condition. The first type uses high speed cameras to observe the deformation and crack generation of expanding specimens showing the final maximum in-plane stretching rate of above , and the second uses soft capturing system recovering typically most fragments successfully. The fragments are measured and investigated using a fragmentation model. The effects of test parameters on the deformation and fracture behavior for three types of structures are discussed in need of modified fragmentation model for shell structural elements.

Effect of links deformation on motion precision of parallel manipulator based on flexible dynamics

2017 ◽  
Vol 44 (6) ◽  
pp. 776-787 ◽  
Author(s):  
Chunxia Zhu ◽  
Jay Katupitiya ◽  
Jing Wang
Keyword(s):  
Parallel Manipulator ◽  
High Speed ◽  
Beam Theory ◽  
Parallel Manipulators ◽  
Dynamic Responses ◽  
Axial Deformation ◽  
Content Type ◽  
High Performing ◽  
Coupling Equations ◽  
The Relationship

Purpose Manipulator motion accuracy is a fundamental requirement for precision manufacturing equipment. Light weight manipulators in high speed motions are vulnerable to deformations. The purpose of this work is to analyze the effect of link deformation on the motion precision of parallel manipulators. Design/methodology/approach The flexible dynamics model of the links is first established by applying the Euler–Bernoulli beam theory and the assumed modal method. The rigid-flexible coupling equations of the parallel mechanism are further derived by using the Lagrange multiplier approach. The elastic energy resulting from spiral motion and link deformations are computed and analyzed. Motion errors of the 3-link torque-prismatic-torque parallel manipulator are then evaluated based on its inverse kinematics. The validation experiments are also conducted to verify the numerical results. Findings The lateral deformation and axial deformation are largest at the middle of the driven links. The axial deformation at the middle of the driven link is approximately one-tenth of the transversal deformation. However, the elastic potential energy of the transversal deformation is much smaller than the elastic force generated from axial deformation. Practical implications Knowledge on the relationship between link deformation and motion precision is useful in the design of parallel manipulators for high performing dynamic responses. Originality/value This work establishes the relationship between motion precision and the amount of link deformation in parallel manipulators.

High-Speed Framing Camera for Photographing Exploding Wire Phenomena

1959 ◽  
pp. 345-364
Author(s):  
F. H. Nadig ◽  
J. L. Bohn ◽  
T. Korneff
Keyword(s):  
High Speed ◽  
Exploding Wire ◽  
Framing Camera

scholarly journals High-speed deformation and fracture of the dioxide-zirconium ceramics and zirconium alumina concrete

2012 ◽  
Vol 26 ◽  
pp. 01055 ◽  
Author(s):  
A. Bragov ◽  
L. Kruszka ◽  
A. Lomunov ◽  
A. Konstantinov ◽  
D. Lamzin ◽  
...  
Keyword(s):  
High Speed ◽  
Deformation And Fracture ◽  
Zirconium Ceramics ◽  
High Speed Deformation

scholarly journals Кинетика структуры титанового сплава при высокоскоростном проникании ударника

2020 ◽  
Vol 62 (11) ◽  
pp. 1769
Author(s):  
С.А. Атрошенко ◽  
А.Ю. Григорьев ◽  
Г.Г. Савенков
Keyword(s):  
Plastic Deformation ◽  
Titanium Alloy ◽  
High Speed ◽  
Deformation And Fracture ◽  
Mechanisms Of Plastic Deformation

Abstract. The article is devoted to the study of the behavior of a titanium alloy under conditions of high-speed penetration at a speed of approximately 2.0 km / s. It is shown that in the target during penetration, three penetration zones are observed that differ in the mechanisms of plastic deformation and fracture.

scholarly journals Flexural Interpretation of Simply Supported Laminated Composite Beam

2020 ◽  
Vol 8 (5) ◽  
pp. 3559-3565
Keyword(s):  
Shear Deformation ◽  
Composite Beam ◽  
Laminated Composite ◽  
Beam Theory ◽  
Composite Beams ◽  
Shear Stresses ◽  
Bending Stress ◽  
Simply Supported ◽  
Laminated Composite Beam ◽  
Laminated Composite Beams

In this Paper, the analysis of simply supported laminated composite beam having uniformly distributed load is performed. The solutions obtained in the form of the displacements and stresses for different layered cross ply laminated composite simply supported beams subjected uniformly distributed to load. Different aspect ratio consider for different results in terms of displacement, bending stress and shear stresses. The shear stresses are calculated with the help of equilibrium equation and constitutive relationship. Using displacement field including trigonometric function of laminated composite beams are derived from virtual displacement principle. There are axial displacement, transverse displacement, bending stress and shear stresses. In addition, Euler-Bernoulli (ETB), First order shear deformation beam theory (FSDT), Higher order shear deformation beam theory (HSDT) and Hyperbolic shear deformation beam theory (HYSDT) solution have been made for comparison and better accuracy of solutions and results of static analyses of laminated composite beams for simply supported laminated composite beam.

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