Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

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Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment

A new approach to the application of Mori-Tanaka's theory in composite materials

The purpose of the present survey is to review the analysis of composite materials from the applied mechanics and engineering science point of view. The subjects under consideration will be analysis of the following properties of various kinds of composite materials: elasticity, thermal expansion, moisture swelling, viscoelasticity, conductivity (which includes, by mathematical analogy, dielectrics, magnetics, and diffusion) static strength, and fatigue failure.

Analysis of Composite Materials—A Survey

Failure plane orientations for transverse loading of a unidirectional fiber composite

The years long in preparation World Wide Failure Exercise II has been completed and the final results and conclusions published. The overall purpose of the World Wide Failure Exercise II was to evaluate the failure criteria/failure theories to be used in the analysis of fiber composite materials. An in-depth consideration of the results from the failure exercise is laid out here. Many critical issues are examined and the status and significance of the World Wide Failure Exercise II is assessed. These results may be of interest and use to researchers and practitioners in the field of composite materials and structures.

The World Wide Failure Exercise II Examination of Results

A recent deterministic derivation for the creep rupture behavior ofpolymers is taken as the basis for the present work. The formulation isthat for the prediction of the lifetime of viscoelastic materials underconstant load, based upon kinetic crack growth from initial flaws. Thestatistical generalization involves using a Weibull type distributionfor the instantaneous static strengths. Then the resulting fullstatistical character for the lifetimes as a function of stress level isfound. The lifetime distributions are determined to be much broader thanare the static strength distributions. An unusual statisticalcharacteristic emerges from the derivation. When the lifetimes areviewed on log stress versus log lifetime scales the envelopes for thevarious probability levels of failure are found to have a common shape,as in a single master curve, but they are shifted relative to each otheralong the log stress axis. This shifting property could haveconsiderable utility in reducing the number of tests required to obtaina complete, statistical database. Finally, similar implications forfatigue characterization are considered.

A probabilistic treatment of creep rupture behavior for polymers and other materials

Interactive mechanical and chemical degradation in organic materials

Necessary and sufficient conditions for composite lamina failure within a laminate are derived from the separate criteria for fiber failure and for matrix failure.

Tensor Transformations and Failure Criteria for the Analysis of Fiber Composite Materials Part II: Necessary and Sufficient Conditions for Laminate Failure

Richard M. Christensen

Papers

Failure plane orientations for transverse loading of a unidirectional fiber composite

The World Wide Failure Exercise II Examination of Results

A probabilistic treatment of creep rupture behavior for polymers and other materials

Interactive mechanical and chemical degradation in organic materials

Tensor Transformations and Failure Criteria for the Analysis of Fiber Composite Materials Part II: Necessary and Sufficient Conditions for Laminate Failure