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Author: J. H. Giovanola Publisher: ISBN: Category : Languages : en Pages : 225
Book Description
This report presents results of a program to improve understanding of dynamic fracture behavior by investigating both crack tip loading conditions and material properties for fracture at high loading rates. A new test procedure, the one-point-bend test was analyzed and further developed the test a wide range of materials at impact loading rates. The test uses inertial loading to load the crack tip and affords an unambiguous measurement of the dynamic initiation toughness. The test's usefulness in producing small controlled increments of crack extension and in crack propagation studies was also demonstrated. Moreover, the concept of inertial loading was extended to study dynamic mixed- mode crack initiation under controlled mixed mode I and II conditions. These new test techniques were used to establish the dynamic fracture behavior of 4340 steel (HRC 50). It was shown that, for loading times to fracture as short as 20 microsecs, no time-modified criterion is necessary to predict crack initiation. The classical fracture criterion equating the applied stress intensity to the dynamic fracture toughness is adequate, provided the dynamically applied stress intensity is correctly evaluated. Under mixed mode I and II loading with (k sub II)/(k sub I) values between 0 and 0.5, it was demonstrated that dynamic crack initiation is essentially controlled by the mode I stress intensity and by the mode I dynamic fracture toughness.
Author: J. H. Giovanola Publisher: ISBN: Category : Languages : en Pages : 225
Book Description
This report presents results of a program to improve understanding of dynamic fracture behavior by investigating both crack tip loading conditions and material properties for fracture at high loading rates. A new test procedure, the one-point-bend test was analyzed and further developed the test a wide range of materials at impact loading rates. The test uses inertial loading to load the crack tip and affords an unambiguous measurement of the dynamic initiation toughness. The test's usefulness in producing small controlled increments of crack extension and in crack propagation studies was also demonstrated. Moreover, the concept of inertial loading was extended to study dynamic mixed- mode crack initiation under controlled mixed mode I and II conditions. These new test techniques were used to establish the dynamic fracture behavior of 4340 steel (HRC 50). It was shown that, for loading times to fracture as short as 20 microsecs, no time-modified criterion is necessary to predict crack initiation. The classical fracture criterion equating the applied stress intensity to the dynamic fracture toughness is adequate, provided the dynamically applied stress intensity is correctly evaluated. Under mixed mode I and II loading with (k sub II)/(k sub I) values between 0 and 0.5, it was demonstrated that dynamic crack initiation is essentially controlled by the mode I stress intensity and by the mode I dynamic fracture toughness.
Author: N. Morozov Publisher: Springer Science & Business Media ISBN: 3540697128 Category : Science Languages : en Pages : 107
Book Description
In this book a new phenomenological approach to brittle medium fracture initiation under shock pulses is developped. It provides an opportunity to estimate fracture of media with and without macrodefects. A qualitative explanation is thus obtained for a number of principally important effects of high-speed dynamic fracture that cannot be clarified within the framework of previous approaches. It is possible to apply this new strategy to resolve applied problems of disintegration, erosion, and dynamic strength determination of structural materials. Specialists can use the methods described to determine critical characteristics of dynamic strength and optimal effective fracture conditions for rigid bodies. This book can also be used as a special educational course on deformation of materials and constructions, and fracture mechanics.
Author: Arun Shukla Publisher: World Scientific ISBN: 9812773320 Category : Technology & Engineering Languages : en Pages : 374
Book Description
Covering a wide variety of topics in dynamic fracture mechanics, this volume presents state-of-the-art experimental techniques and theoretical analysis on dynamic fracture in standard and exotic materials. Written by world renowned researchers, this valuable compendium contains eleven chapters on crack initiation, crack propagation, crack arrest, crack-stress wave interactions, and experimental, analytical and numerical methods in dynamic fracture mechanics. Contents: Modeling Dynamic Fracture Using Large-Scale Atomistic Simulations (H-J Gao & M J Buehler); Dynamic Crack Initiation Toughness (D Rittel); The Dynamics of Rapidly Moving Tensile Cracks in Brittle Amorphous Material (J Fineberg); Optical Methods for Dynamic Fracture Mechanics (H V Tippur); On the Use of Strain Gages in Dynamic Fracture (V Parameswaran & A Shukla); Dynamic and Crack Arrest Fracture Toughness (R E Link & R Chona); Dynamic Fracture in Graded Materials (A Shukla & N Jain); Dynamic Fracture Initiation Toughness at Elevated Temperatures with Application to the New Generation of Titanium Aluminides Alloys (M Shazly et al.); Dynamic Fracture of Nanocomposite Materials (A Shukla et al.). Readership: Researchers, practitioners, and graduate students in fracture mechanics and materials science.
Author: Arun Shukla Publisher: Springer Science & Business Media ISBN: 1441904468 Category : Science Languages : en Pages : 416
Book Description
Dynamic Failure of Materials and Structures discusses the topic of dynamic loadings and their effect on material and structural failure. Since dynamic loading problems are very difficult as compared to their static counterpart, very little information is currently available about dynamic behavior of materials and structures. Topics covered include the response of both metallic as well as polymeric composite materials to blast loading and shock loadings, impact loadings and failure of novel materials under more controlled dynamic loads. These include response of soft materials that are important in practical use but have very limited information available on their dynamic response. Dynamic fragmentation, which has re-emerged in recent years has also been included. Both experimental as well as numerical aspects of material and structural response to dynamic loads are discussed. Written by several key experts in the field, Dynamic Failure of Materials and Structures will appeal to graduate students and researchers studying dynamic loadings within mechanical and civil engineering, as well as in physics and materials science.
Author: Donald A. Shockey Publisher: ISBN: Category : Fracture mechanics Languages : en Pages : 39
Book Description
Classical concepts of Griffith-Irwin fracture mechanics were extended to include time effects and hence to apply to crack instability under dynamic loads. Theoretical considerations of the stress intensity histories experienced by cracks subjected to short pulse loads suggested that instability requires the crack tip stress intensity to exceed the dynamic toughness for a minimum time. This postulate was checked by experiments. Impact techniques were used to produce well-defined stress pulses in specimens of an epoxy, 4340 steel, 1018 steel, and 6061-T6 aluminum containing cracks of several lengths to observe crack instability behavior. The experimental results were not well described by static fracture mechanics, but were in accord with the minimum time postulates deduced from stress intensity histories. The understanding gained from the research program promises to be useful in assessing the safety of structures under dynamic loads, in characterizing the dynamic fracture resistance of materials, and in designing equipment and procedures for measuring dynamic fracture toughness. The relationship between dynamic initiation toughness and dynamic propagation toughness was addressed. The temperature histories in material near a rapidly propagating crack in a steel plate were measured and used to compute the heat of fracture and the dynamic propagation toughness. Simultaneous measurements of the dynamic stress intensity were made using the shadow optical method of caustics and high speed photography.
Author: Rodrigo Enrique Chavez Morales Publisher: ISBN: Category : Languages : en Pages : 149
Book Description
Polymeric materials, in particular composite materials, have seen an increase in use in naval applications. Under these conditions, structural materials need to be able to withstand dynamic loads such as those from underwater blast and wave slamming, as well as environmental factors like moisture absorption and ultraviolet radiation. Both conditions add challenges in the design process due to complex loading conditions and change in material behavior. This dissertation presents an experimental study to understand the dynamic fracture behavior of poly(methyl methacrylate) (PMMA) and carbon fiber/epoxy. Dynamic loading was obtained by launching projectiles from a gas gun onto the specimen. A combination of ultra high-speed photography and digital image correlation was used to gather full-field experimental data. First, a methodology was established using PMMA to obtain pure mode-II fracture loading conditions. This study generated valuable experimental results, which updated current data available to the fracture community. Sharp transitions from mode-II to mode-I fracture loading were observed in addition to the effect of crack-tip sharpness and loading conditions on the crack path. Next, carbon fiber/epoxy specimens were studied after developing an experimental setup capable of obtaining dynamic mode-II loading conditions. The effect of moisture absorption on the fracture behavior of unidirectional carbon fiber/epoxy samples was studied. Two different methods were used to obtain significant moisture contents, first, samples were hygrothermally aged at 65°C for 28 days and second, submersion in room temperature distilled water for 400 days. Additionally, a control group of samples with no moisture content was used to compare results. This study determined that moisture absorption decreased the fracture toughness of the material, however no differences were observed between the different aging methods. Last, unidirectional and woven carbon fiber samples were subject to mixed mode loading. The samples were hygrothermally aged at 65°C until they achieved moisture saturation. Mixed mode loading and woven composites allowed for the opportunity to create more realistic conditions compared to unidirectional composites under pure mode-II fracture. At the same time, these changes introduced complexities at the onset of crack growth. Unlike the previous experiment, the samples showed no sensitivity to moisture.
Author: K. Ravi-Chandar Publisher: Elsevier ISBN: 0080472559 Category : Science Languages : en Pages : 265
Book Description
Dynamic fracture in solids has attracted much attention for over a century from engineers as well as physicists due both to its technological interest and to inherent scientific curiosity. Rapidly applied loads are encountered in a number of technical applications. In some cases such loads might be applied deliberately, as for example in problems of blasting, mining, and comminution or fragmentation; in other cases, such dynamic loads might arise from accidental conditions. Regardless of the origin of the rapid loading, it is necessary to understand the mechanisms and mechanics of fracture under dynamic loading conditions in order to design suitable procedures for assessing the susceptibility to fracture. Quite apart from its repercussions in the area of structural integrity, fundamental scientific curiosity has continued to play a large role in engendering interest in dynamic fracture problems In-depth coverage of the mechanics, experimental methods, practical applications Summary of material response of different materials Discussion of unresolved issues in dynamic fracture
Author: Bo Song Publisher: Springer ISBN: 3319069950 Category : Technology & Engineering Languages : en Pages : 386
Book Description
Dynamic Behavior of Materials, Volume 1: Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics, the first volume of eight from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental Mechanics, including papers on: · General Dynamic Materials Response · Novel Dynamic Testing Techniques · Dynamic Fracture and Failure · Dynamic Behavior of Geo-materials · Dynamic Behavior of Composites and Multifunctional materials · Dynamic Behavior of Low-Impedance materials · Dynamic Modeling and Simulation of Dynamic Behavior of Materials · Quantitative Visualization of Dynamic Behavior of Materials · Shock/Blast Loading of Materials · Interface and Structural Dynamics · Material Response
Author: J. H. Giovanola
Author: J. H. Giovanola
Author: N. Morozov
Author: L. B. Freund
Author: Arun Shukla
Author: Arun Shukla
Author: Donald A. Shockey
Author: Rodrigo Enrique Chavez Morales
Author: A. S. Tetelman
Author: K. Ravi-Chandar
Author: Bo Song