Three-dimensional stress analysis of textile composites: Part I. Numerical analysis

This paper is a personal account of the origin and development of the twinned-calcite strain gauge, its experimental verification, and its relationship to stress analysis. The method allows the calculation of the three-dimensional deviatoric strain tensor based on five or more twin sets. A minimum of about 25 twin sets should provide a reasonably accurate result for the magnitude and orientation of the strain tensor. The opposite-signed strain axis orientation is the most accurately located. Where one strain axis is appreciably different from the other two, that axis is generally within about 10° of the correct value. Experiments confirm a magnitude accuracy of 1% strain over the range of 1–12% axial shortening and that samples with more than 40% negative expected values imply multiple or rotational deformations. If two deformations are at a high angle to one another, the strain calculated from the positive and negative expected values separately provides a good estimate of both deformations. Most stress analysis techniques do not provide useful magnitudes, although most provide a good estimate of the principal strain axis directions. Stress analysis based on the number of twin sets per grain provides a better than order-of-magnitude approximation to the differential stress magnitude in a constant strain rate experiment.

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Optimization of the Navy’s three-dimensional mine impact burial prediction simulation model, Impact35, using high-order numerical methods

The Journal of Defense Modeling and Simulation Applications Methodology Technology ◽

10.1177/15485129211028661 ◽

2021 ◽

pp. 154851292110286

Author(s):

Athanasios Donas ◽

Ioannis Famelis ◽

Peter C Chu ◽

George Galanis

Keyword(s):

Numerical Analysis ◽

Numerical Methods ◽

Prediction Model ◽

Simulation Model ◽

Three Dimensional ◽

Simulation System ◽

High Order ◽

Alternative Methodology ◽

Runge Kutta ◽

Fifth Order

The aim of this paper is to present an application of high-order numerical analysis methods to a simulation system that models the movement of a cylindrical-shaped object (mine, projectile, etc.) in a marine environment and in general in fluids with important applications in Naval operations. More specifically, an alternative methodology is proposed for the dynamics of the Navy’s three-dimensional mine impact burial prediction model, Impact35/vortex, based on the Dormand–Prince Runge–Kutta fifth-order and the singly diagonally implicit Runge–Kutta fifth-order methods. The main aim is to improve the time efficiency of the system, while keeping the deviation levels of the final results, derived from the standard and the proposed methodology, low.

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Three-dimensional overall stress analysis for double-coated structure with equal coating thickness

Mechanics of Materials ◽

10.1016/j.mechmat.2021.103861 ◽

2021 ◽

Vol 158 ◽

pp. 103861

Author(s):

Shou-Ming Shang ◽

Peng-Fei Hou ◽

Wen-Hua Zhang

Keyword(s):

Stress Analysis ◽

Coating Thickness ◽

Three Dimensional

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Air Ventilation Performance of School Classrooms with Respect to the Installation Positions of Return Duct

Sustainability ◽

10.3390/su13116188 ◽

2021 ◽

Vol 13 (11) ◽

pp. 6188

Author(s):

Sungwan Son ◽

Choon-Man Jang

Keyword(s):

Air Quality ◽

Numerical Analysis ◽

Indoor Air Quality ◽

Indoor Air ◽

Three Dimensional ◽

Cross Infection ◽

School Students ◽

Height Range ◽

Air Ventilation ◽

Ventilation Performance

For students, who spend most of their time in school classrooms, it is important to maintain indoor air quality (IAQ) to ensure a comfortable and healthy life. Recently, the ventilation performance for indoor air quality in elementary schools has emerged as an important social issue due to the increase in the number of days of continuous high concentrations of particulate matter. Three-dimensional numerical analysis has been introduced to evaluate the indoor airflow according to the installation location of return diffusers. Considering the possibility of the cross-infection of infectious diseases between students due to the direction of airflow in the classroom, the airflow angles of the average respiratory height range of elementary school students, between 1.0 and 1.5 m, are analyzed. Throughout the numerical analysis inside the classroom, it is found that the floor return system reduces the indoor horizontal airflow that causes cross-infection among students by 20% compared to the upper return systems. Air ventilation performance is also analyzed in detail using the results of numerical simulation, including streamlines, temperature and the age of air.

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