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This report results from a contract tasking University of Cassino as follows: The contractor shall investigate the behavior of ductile metals under high strain rates at various temperatures. The contractor shall produce a new advanced model for predicting ductile failure in metals using continuum mechanics and solid state equations.

This report results from a contract tasking University of Cassino as follows: The contractor shall investigate the behavior of ductile metals under high strain rates at various temperatures. The contractor shall produce a new advanced model for predicting ductile failure in metals using continuum mechanics and solid state equations.

https://gioumeh.com/product/advanced-mechanics-of-materials-solution/ ------------------------------------------------- Authors:  Arthur P. Boresi, Richard J. Schmidt   Published:  Wiley 2003   Edition:  6th   Pages:   493   Type:  pdf   Size:   24MB Sample:   Solution sample file   Download After Payment

Composite materials have been frequently used in aerospace vehicles. Very often defects are inherited during the manufacture and damages are inherited during the construction and services. It becomes critical to understand the mechanical behavior of such composite structure before it can be further used. One good example of these composite structures is the cylindrical bottle of solid rocket motor case with accidental impact damages. Since the replacement of this cylindrical bottle is expensive, it is valuable to know how the damages affects the material, and how it can be repaired. To reach this goal, the damage must be characterized and the stress/strain field must be carefully analyzed. First the damage area, due to impact, is surveyed and identified with a shearography technique which uses the principle of speckle shearing interferometry to measure displacement gradient. Within the damage area of a composite laminate, such as the bottle of solid rocket motor case, all layers are considered to be degraded. Once a lamina being degraded the stiffness as well as strength will be drastically decreased. It becomes a critical area of failure to the whole bottle. And hence the stress/strain field within and around a damage should be accurately evaluated for failure prediction. To investigate the stress/strain field around damages a Hybrid-Numerical method which combines experimental measurement and finite element analysis is used. It is known the stress or strain at the singular point can not be accurately measured by an experimental technique. Nevertheless, if the location is far away from the singular spot, the displacement can be found accurately. Since it reflects the true displacement field locally regardless of the boundary conditions, it is an excellent input data for a finite element analysis to replace the usually assumed boundary conditions. Therefore, the Hybrid-Numerical method is chosen to avoid the difficulty and to take advantage of both experimental technique and finite element analysis. Experimentally, the digital image correlation technique is employed to measure the displacement field. It is done by comparing two digitized images, before and after loading. Numerically, the finite element program, ABAQUS (version 5.2), is used to analyze the stress and strain field. It takes advantage of the high speed and huge memory size of modern supercomputer, CRAY Y-MP, at NASA Marshall Space Flight Center.

This project focused on the development of multiscale models for molecular crystals, with special emphasis on the secondary explosive cyclotrimethylene trinitramine (RDX). Physical understanding related to the molecular scale mechanics of this material was also developed. This data is used as starting point for the definition of physically-based coarse grained models. In turn, these models are to assist the design of new energetic materials with enhanced energy release rates and reduced sensitivity to unintentional detonation. The following results have been obtained: a) we investigated conformational stability of the RDX molecule in the crystal as a function of temperature and determined the density of conformers in steady state at temperatures between room and melting, b) we identified the stable dislocations in RDX and, for the first time, established a ranking of slip systems in terms of the Peierls stress (critical stress for dislocation motion), c) we discovered a family of point defects which are rotated and distorted molecules embedded in an otherwise perfect crystal; the stability of such point defects was demonstrated with DFT simulations and a method was proposed to detect them experimentally using Raman spectroscopy, d) we are currently investigating the effect of temperature on the ranking of slip systems, which is a result needed in crystal plasticity models of hot spot formation, e) we developed a family of coarse grained models for the RDX crystal in which the molecules are gradually coarse grained to higher and higher degrees, ranging from full atomistic detail to rigid blobs, and we determined the level of error introduced by coarse graining in various macroscopic measures of crystal thermo-mechanics.

This project focused on the development of multiscale models for molecular crystals, with special emphasis on the secondary explosive cyclotrimethylene trinitramine (RDX). Physical understanding related to the molecular scale mechanics of this material was also developed. This data is used as starting point for the definition of physically-based coarse grained models. In turn, these models are to assist the design of new energetic materials with enhanced energy release rates and reduced sensitivity to unintentional detonation. The following results have been obtained: a) we investigated conformational stability of the RDX molecule in the crystal as a function of temperature and determined the density of conformers in steady state at temperatures between room and melting, b) we identified the stable dislocations in RDX and, for the first time, established a ranking of slip systems in terms of the Peierls stress (critical stress for dislocation motion), c) we discovered a family of point defects which are rotated and distorted molecules embedded in an otherwise perfect crystal; the stability of such point defects was demonstrated with DFT simulations and a method was proposed to detect them experimentally using Raman spectroscopy, d) we are currently investigating the effect of temperature on the ranking of slip systems, which is a result needed in crystal plasticity models of hot spot formation, e) we developed a family of coarse grained models for the RDX crystal in which the molecules are gradually coarse grained to higher and higher degrees, ranging from full atomistic detail to rigid blobs, and we determined the level of error introduced by coarse graining in various macroscopic measures of crystal thermo-mechanics.

Book Source: Digital Library of India Item 2015.90070 dc.contributor.author: Murphy, Glenn dc.date.accessioned: 2015-06-30T21:36:20Z dc.date.available: 2015-06-30T21:36:20Z dc.date.digitalpublicationdate: 2005-01-29 dc.date.citation: 1946 dc.identifier.barcode: 148712 dc.identifier.origpath: /data7/upload/0175/062 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/90070 dc.description.scannerno: 3 dc.description.scanningcentre: RMSC, IIIT-H dc.description.main: 1 dc.description.tagged: 0 dc.description.totalpages: 328 dc.format.mimetype: application/pdf dc.language.iso: English dc.publisher.digitalrepublisher: Digital Library Of India dc.publisher: Mcgraw-hill Book Company,inc. dc.rights: Copyright Permitted dc.source.library: Osmania University dc.subject.classification: Natural Sciences dc.subject.classification: Physics dc.title: Advanced Mechanics Of Materials

Book Source: Digital Library of India Item 2015.90070 dc.contributor.author: Murphy, Glenn dc.date.accessioned: 2015-06-30T21:36:20Z dc.date.available: 2015-06-30T21:36:20Z dc.date.digitalpublicationdate: 2005-01-29 dc.date.citation: 1946 dc.identifier.barcode: 148712 dc.identifier.origpath: /data7/upload/0175/062 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/90070 dc.description.scannerno: 3 dc.description.scanningcentre: RMSC, IIIT-H dc.description.main: 1 dc.description.tagged: 0 dc.description.totalpages: 328 dc.format.mimetype: application/pdf dc.language.iso: English dc.publisher.digitalrepublisher: Digital Library Of India dc.publisher: Mcgraw-hill Book Company,inc. dc.rights: Copyright Permitted dc.source.library: Osmania University dc.subject.classification: Natural Sciences dc.subject.classification: Physics dc.title: Advanced Mechanics Of Materials

BORESI

BORESI

Mechanics of Advanced Materials and Structures is an active peer-reviewed academic journal covering mechanics aspects of composite materials and structures. It was established in 1994 and is published 24 times a year (16/yr. until 2019; 12/yr. until 2017) by Taylor & Francis Inc. The journal focuses on research in the mechanics and behaviour of advanced materials, featuring articles, research papers, and technical notes that contribute to the understanding of the mechanical properties, performance, and applications of advanced materials and structures. The scope of the journal includes studies on material testing, structural analysis, fracture mechanics, and the design of advanced engineering materials as well as analytical, numerical, experimental and hybrid methods on the mechanics of advanced materials and structures and layered structures at various scales. The Internet Archive Collection contains microfilm published between 1996 and 1998 Mechanics of Advanced Materials and Structures can be found online at: www.tandfonline.com/loi/umcm20 The ISSN is: 1537-6494 Publication History Mechanics of Composite Materials and Structures 1075-9417 Formerly (until 2002) GBR United Kingdom

680 p. 24 cm

680 p. 24 cm

680 p. 24 cm

680 p. 24 cm