Japan Agency for Marine-Earth Science and Technology

Other

Nagaoka University of Technology

Hide Sakaguchi

Kazumichi Yanagisawa

Arito Sakaguchi

Daisuke Nishiura

Miki Yamamoto

A particle simulation device comprises: a position information acquisition unit that acquires position information for the particles; a pair setting unit that selects pairs of particles and sets a pair number, on the basis of the position information; a reference information generation unit that generates a matrix from the pair numbers and the particle numbers, and generates reference information for referencing the pair numbers from the particle numbers on the basis of a matrix in which the order of the rows of the matrix are sorted on the basis of the particle numbers; a sum calculation unit that calculates a sum of interaction forces for each particle on the basis of the reference information; and a particle information calculation unit that calculates the position and velocity of the particles on the basis of the sum of interaction forces.

Particle simulation device, particle simulation method, and particle simulation program

It is an object to provide a stress history measurement method and a stress sensor by which the stress history of an object being measured can be measured easily with high accuracy over a wide stress measurement range. In the stress history measurement method, the stress history to which the object being measured has been subjected is measured on the basis of the ratio of twinned calcite particles after the object to be measured has been subjected to an external force, the object having a stress sensor embedded therein and capable of being deformed elastically when being subjected to the external force, the sensor including a number of calcite particles. The stress sensor is configured such that a number of calcite particles are hardened by a resin with adjacent particles kept in contact with each other.

Stress history measurement method and stress sensor

There are provided a method by which a stress history of an object can be measured with high reliability if the object, which has temporarily been elastically deformed upon receiving an external force, recovers from the elastic deformation, and a composite material containing cement as a main component, of which a stress history can be measured with high reliability without reducing the strength of the material itself and without breaking the structure. To achieve the above-mentioned advantages, the method includes the steps of: acquiring an initial value of a twin density for calcite particles contained in an object to be measured that is elastically deformable upon receiving an external force; and measuring a history of stresses received by the object to be measured on the basis of a difference from the initial value in respect of the twin density for the calcite particles after the object to be measured receives the external force. The composite material includes calcite particles, for which a twin density is known and which are mixed to be distributed in the material, partially replacing an aggregate of the material.

Method of measuring stress history and composite material containing cement as main component

The memory size used in DEM calculation of particle having a particle diameter distribution is suppressed. A particle simulator includes a particle-information retaining unitholding particle information including position and velocity information of a particle group, a particle-number changing unitassigning particle numbers specifying particles in an order in accordance with the positions of the particles to the particle, a contact-candidate-list preparing unitselecting particle pairs of a target particle and another particle that may be in contact with the target particle, a contact determining unitcalculating contact forces generated between particles in the particle pairs on the basis of particle information and storing the contact forces in the contact-force tables, a contact-force calculating unitextracting contact forces of particles having a diameter greater than particles from contact-force tables using a contact-force reference table, extracting contact forces of particles having a diameter smaller than the particles by specifying the storage positions in the contact-force tables using integrated-contact-candidate numbers s_jgi[i], and calculating the sum of the contact forces, and a particle-information updating unitupdating the particle information on the basis of the contact forces of the particle.

Particle simulator and method of simulating particles

When an integrated displacement amount of the particles constituting a contact candidate pair is equal to or more than &#xbc; (one-quarter) cell or more, likelihood becomes high that the particles of the contact candidate particle pair, which was not in contact with each other, would come into contact with each other. Then, in such high likelihood, data relating to contact candidate particle pairs are updated. With this arrangement, even if contact candidate particle pair data updating is decimated and part of contact determination is accordingly omitted to increase a computing speed of the contact determination, accuracy of simulation will not be reduced. Thus, according to the present invention, the computing speed of the contact determination can be increased without lowering the accuracy of simulation.

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Yokosuka, Japan

Hide Sakaguchi