It is 100 years since the well-know Mohr-Coulomb strength theory was established in 1900. A considerable amount of theoretical and experimental research on strength theory of materials under complex stress state was done in the 20th Century. This review article presents a survey of the advances in strength theory (yield criteria, failure criterion, etc) of materials (including matellic materials, rock, soil, concrete, ice, iron, polymers, energetic material, etc) under complex stress, discusses the relationship among various criteria, and gives a method of choosing a reasonable failure criterion for applications in research and engineering. Three series of strength theories, the unified yield criterion, the unified strength theory, and others are summarized. This review article contains 1163 references regarding the strength theories. This review also includes a biref discussion of the computational implementation of the strength theories and multi-axial fatigue.

Advances in strength theories for materials under complex stress state in the 20th Century

https://faculty.ucmerced.edu/gdiaz/resume/IJHMT_2001.pdf

Dynamic prediction and control of heat exchangers using artificial neural networks

Experiments have been performed to study convective heat transfer in the entrance region of corrugated channels. With water as the working fluid, two channel spacings were examined for a single corrugation angle of 20°. The flow rate was varied over the range I50 ≤ Re ≤ 4000. Flow visualization under low-Reynolds-number flow conditions suggested the presence of longitudinal vortices, while at somewhat higher Reynolds numbers, the existence of spanwise vortices was clearly revealed. For Re > 1500, Nusselt numbers in the corrugated channels exceeded those in the parallel-plate channel by approximately 140% and 240% for the two channel spacings, the corresponding increases in friction factor being 130% and 280%. Performance evaluations under the criteria of equal mass flow rate, equal pumping power, and equal pressure drop per unit length established both the corrugated channels as superior to the parallel-plate channel in intensifying heat transfer.

Experiments on convective heat transfer in corrugated channels

The effects of inlet fluid flow nonuniformity on thermal performance and pressure drops in crossflow plate-fin compact heat exchangers

The combined effects of wall longitudinal heat conduction, inlet fluid flow nonuniformity and temperature nonuniformity in compact tube–fin heat exchangers: a finite element method

The transient responses to a step change in an inlet temperature are analyzed as an important example of dynamic characteristics of cross-flow heat exchangers with both fluids unmixed. The numerical calculations are performed by two methods, namely, a method expanding a finite difference method used by Myers et al. to calculate accurately in the case where temperature changes discontinuously, and a central finite difference method to calculate more accurately with a small number of nodes in large values of a heat capacity of a solid wall. Consequently, the effects of an initial condition and the various parameters concerning heat transfer performance on the transient responses in the temperature efficiency are shown.

Analysis of the Dynamic Characteristics of Cross-Flow Heat Exchangers with Both Fluids Unmixed : On the Transient Responses to a Step Change in the Inlet Temperature

In case where the overall heat transfer coefficient K varies with positions on the heat exchanger surface or fluid temperature in the cross-flow exchanger, the relations between the number of heat transfer units and the temperature efficiency e are obtained analytically or numerically, assuming that K = 1+mxn or K = 1+mθn in the nondimensional form referred to the standard value K0. The effects of parameters m and n are shown quantitatively, arranging the calculated results by the ratio of the efficiency change (e-e0)/e0, where e0 is the temperature efficiency for K = K0 and by the single overall coefficient signifying "true mean overall coefficient". Further, it is shown that there is considerable difference among flow arrangements and that conventional methods are not sufficient for large value of m.

Performance of the Cross-Flow Heat Exchanger with Variable Physical Properties : 1st Report, In Case where the Overall Heat Transfer Coefficient Is Variable

A plastic deformation whose strain trajectory has constant curvature is investigated on mild steel by applying the combined load of axial force and torsion to thin-walled tubular specimen. The experiment is performed by using a full-automatic complex loading testing machine. Experimental result shows that the relation between the magnitude of stress vector and the arc length of plastic strain trajectory depends mainly on the curveture, and the curve showing such a relation appears higher than the hardening curve for pure torsion. On the other hand, cyclic loading makes the curve lower than the hardening curve for pure torsion owing to the effect of cyclic softening. This may be an experimental evidence that the conventional flow theory is not satisfactory for complex loading. However, the flow theory may be found as a sufficient approximation to plastic deformation under complex loading with strain trajectory of constant radius of curvature larger than 2 percent.

Plastic deformation of mild steel under combined load of axial force and torsion with strain trajectories of constant curvature

Corrugated wall channels are investigated as a means of augmenting forced-convection heat transfer with a single-phase flow in heat exchangers. The fluid flow state and the heat transfer characteristic of the parallel channels bent many times, which are appropriate models of corrugated wall channels, are analyzed by the finite difference method with an adequate "periodic boundary condition" for the laminar flow where the pitch P=1∼8, the bending angle θ=0°∼90° and Reynolds number Re=0∼2400, and for the turbulent flow where P=1∼8, θ=90° and Re=40000. Consequently, the effects of P and θ on the aspect of flow, the distributions of the wall shear stresses and the local Nusselt numbers, the pressure loss and the mean Nusselt number are clarified, and the performance of the corrugated wall channels as heat exchangers is estimated in terms of the volume goodness factor.

Fluid Flow and Heat Transfer in Corrugated Wall Channels : 4th Report, Analysis in the Case Where Channels Are Bent Many Times

Corrugated wall channels are investigated as a means of augmenting forced-convection heat transfer with a single-phase flow in heat exchangers. Fluid flow states and heat transfer characteristics of parallel channels bent two times which are fundamental elements of corrugated wall channels are examined by numerical analyses and experiments for the pitch P=3 and the bending angle θ=0°∼90°. Consequently, effects of bending angles on aspects of flow, wall shear stress and local Nusselt number distributions, presure losses and mean Nusselt numbers are clarified, and adequate values of bending angles are examined.

Hiroshi Yamashita

Papers

Analysis of the Dynamic Characteristics of Cross-Flow Heat Exchangers with Both Fluids Unmixed : On the Transient Responses to a Step Change in the Inlet Temperature

Performance of the Cross-Flow Heat Exchanger with Variable Physical Properties : 1st Report, In Case where the Overall Heat Transfer Coefficient Is Variable

Plastic deformation of mild steel under combined load of axial force and torsion with strain trajectories of constant curvature

Fluid Flow and Heat Transfer in Corrugated Wall Channels : 4th Report, Analysis in the Case Where Channels Are Bent Many Times

Fluid Flow and Heat Transfer in Corrugated Wall Channels : 3rd Report, Effects of Bending Angles in the Case Where Channels Are Bent Two Times