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

The effects of ultrasonic nanocrystal surface modification temperature on the mechanical properties and fretting wear resistance of Inconel 690 alloy

A review of fretting study on nuclear power equipment

Investigation on fretting wear behavior of 690 alloy in water under various temperatures

Effect of pH value on the fretting wear behavior of Inconel 690 alloy

http://www.ysxbcn.com/down/2014/02_en/09-p0360.pdf

Fretting wear behavior of Inconel 690 in hydrazine environments

Study on the fretting maps of Zircaloy-4 alloy against Inconel 718 alloy

The invention relates to a constant temperature wiggly corrosive wear testing device and a test method thereof. A medium cavity of a high ball discharge test piece is arranged on the periphery of a lower clamp of the testing device, and the cavity is filled with test medium; the wall of the cavity is of a sandwich layer structure, the lower part of the sandwich layer is provided with a water inlet, the upper part is provided with a water outlet, the water inlet is connected with a constant temperature water bath kettle by a miniature water pump, and the water outlet is directly connected withthe constant temperature water bath kettle, thereby forming a constant temperature water circulation system; an auxiliary electrode and a reference electrode are immersed in test medium of the mediumcavity; and the auxiliary electrode, the reference electrode and the upper end face of an upper test piece are respectively connected with the corresponding port of a microprocessor controlled electrochemical workstation by conducting lines so as to form an electrochemical corrosion test system. The testing device and the method thereof can conveniently wear materials in the constant temperature test medium by wiggly corrosion, thereby much more factually and accurately testing the wiggly corrosive wear property of the materials in the specific corrosion medium; and the testing device and themethod thereof provide much more accurate and reliable test basis for corresponding design, so that the properties and the service lives of equipment and apparatus can be increased.

Constant temperature wiggly corrosive wear testing device and test method thereof

The invention discloses a tester and a method for testing test environment controllable multi-directional fine motion fatigue. The tester comprises a vertical fine motion mechanism and a transverse fine motion mechanism, wherein the vertical fine motion mechanism consists of an electromagnetic excitation actuator, a force transducer I, an upper clamp for clamping a spherical upper test piece and the like; the transverse fine motion mechanism consists of a lower clamp for clamping a planar lower test piece, a force transducer II, a piezoelectric ceramic actuator, a longitudinal and transverse two-dimensional moving platform and the like; the vertical fine motion mechanism and the transverse fine motion mechanism are covered by a lower atmosphere cover and an upper atmosphere cover to form an atmosphere control space; and the periphery of the lower clamp is provided with a liquid medium groove higher than the planar test piece. Through the tester, a tightly matched friction pair can carry out multi-directional fine motion in a specific atmosphere and/or a liquid environment controlled artificially, thus the multi-directional fine motion frictional wear performance of a material under the specific environment condition is tested really and accurately, an accurate and reliable proof is provided for related design, use and maintenance of machinery and bioengineering, the properties of equipment and apparatuses are improved, and the service lives of the equipment and the apparatuses are prolonged.

Tester and method for testing test environment controllable multi-directional fine motion fatigue

The fretting wear behavior of the nuclear power material Incoloy 800 was investigated in this study. A PLINT high-temperature fretting tester was used on an Incoloy 800 cylinder against a 304SS cylinder at vertical cross contact under different temperatures (25, 300, and 400°C). During testing, a normal load of 80 N was applied, and the displacement amplitudes ranged from 2 to 40 µm. The fretting wear mechanism at high temperatures and the kinetic character of the materials of the Incoloy 800 steam generator tube were analyzed. Results showed that the fretting running regimes varied little with ncreasing temperature, and some microcracks were observed in both the mixed fretting regime (MFR) and the partial slip regime (PSR) at high temperatures. Slight abrasive wear and microcracks were the main wear mechanisms of the Incoloy 800 alloy in PSR, whereas those in the MFR and the gross slip regime were oxidative wear, abrasive wear, and delamination.

Pingdi Ren

Papers

Fretting wear behavior of Inconel 690 in hydrazine environments

Study on the fretting maps of Zircaloy-4 alloy against Inconel 718 alloy

Constant temperature wiggly corrosive wear testing device and test method thereof

Tester and method for testing test environment controllable multi-directional fine motion fatigue

Experimental Study of the Fretting Wear Behavior of Incoloy 800 Alloy at High Temperature