Stress-Focusing Effect in a Uniformly Heated Cylindrical Rod

1976 ◽  
Vol 43 (3) ◽  
pp. 464-468 ◽  
Author(s):  
Chih-Horng Ho
Keyword(s):  
Cross Section ◽  
Temperature Rise ◽  
Dynamic Stress ◽  
Peak Stress ◽  
Stress Waves ◽  
Uniform Temperature ◽  
Focusing Effect ◽  
Tension And Compression ◽  
Very High ◽  
Heating Duration

A long cylindrical rod is considered brought suddenly to a uniform temperature rise over its cross section. Stress-focusing effects occur when stress waves reflect from the outer surface of the rod and proceed radially inward to the axis. The focusing effect can cause a very high peak dynamic stress in both tension and compression in the rod. The magnitude of the peak stress depends upon the magnitude of the temperature rise and the effective heating duration. For instantaneous heating, the infinite peak of stress propagates outward from the center while these peaks are finite for nonzero heating duration. The solutions are carried out by using Laplace transform on time and presented as infinite series summations after the end of heating.

On Stress-Focusing Effect in a Uniformly Heated Solid Sphere

2003 ◽  
Vol 70 (2) ◽  
pp. 304-309 ◽  
Author(s):  
H. J. Ding ◽  
H. M. Wang ◽  
W. Q. Chen
Keyword(s):  
Temperature Rise ◽  
Stress Responses ◽  
Constant Pressure ◽  
Integral Transform ◽  
External Surface ◽  
Separation Of Variables ◽  
Solid Sphere ◽  
Uniform Temperature ◽  
Focusing Effect ◽  
Isotropic Solid

By using the separation of variables technique, the dynamic thermal stress responses in an isotropic solid sphere subjected to uniform temperature rise all over the sphere and a sudden constant pressure at the external surface are performed successfully. The analytical solutions of the radial and hoop dynamic stresses at the center are also obtained. By means of the present method, integral transform can be avoided. Numerical results denote that a very high dynamic stress peak appears periodically at the center of the isotropic solid sphere subjected to uniform temperature rise all over the sphere and a sudden constant pressure at the external surface.

Stress-Focusing Effect in a Uniformly Heated Solid Sphere

1991 ◽  
Vol 58 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Toshiaki Hata
Keyword(s):  
Arrival Time ◽  
Solid Sphere ◽  
Stress Waves ◽  
Ray Theory ◽  
Reflected Waves ◽  
Focusing Effect ◽  
Inverse Transform ◽  
Ray Path ◽  
Very High ◽  
Constant Period

The ray theory is applied to the stress-focusing effects in a uniformly heated solid sphere. The stress-focusing effect is the phenomenon that, under an instantaneous heating, stress waves reflected from the free surface of the sphere result in very high stresses at the center. Using the ray theory, the Laplace transformed solution of stress waves in the sphere is sorted out into rays according to the ray path of multiply-reflected waves. Inverse transform of each ray gives rise to the exact solution of the transient response up to the arrival time of the next ray. The numerical results reveal that stresses peak out periodically at a constant period and, unlike the case of cylinder, the radial stress at the center of the sphere is bounded.

Reconsideration of the Stress-Focusing Effect in a Uniformly Heated Solid Cylinder

1994 ◽  
Vol 61 (3) ◽  
pp. 676-680 ◽  
Author(s):  
T. Hata
Keyword(s):  
Free Surface ◽  
Infinite Series ◽  
Stress Waves ◽  
Ray Theory ◽  
Solid Cylinder ◽  
Reflected Waves ◽  
Focusing Effect ◽  
Ray Path ◽  
Very High ◽  
Constant Period

The stress-focusing effect is the phenomenon that, under an instantaneous heating, stress waves reflected from the free surface of the cylinder result in very high stresses at the center. Ho solved the problem by using Laplace transform on time and presented the solution as infinite series summations, which converge very slowly for certain combinations of time and the radius of a cylinder. However, adopting a concept of the ray theory, the solution of stress waves in the cylinder is sorted out into rays according to the ray path of multiply reflected waves. The results expressed in an infinite series reveal that stresses peak out periodically at a constant period and the order of singularity of the stresses in a cylinder is O(ρ−2).

scholarly journals Cross section to multiplicity ratios at very high energy

2014 ◽  
Vol 734 ◽  
pp. 207-209 ◽  
Author(s):  
M.M. Block ◽  
L. Stodolsky
Keyword(s):  
Cross Section ◽  
High Energy ◽  
Very High Energy ◽  
Very High

scholarly journals Production of radioisotopes within a plasma focus device

2005 ◽  
Vol 20 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Ergisto Angeli ◽  
Agostino Tartari ◽  
Michele Frignani ◽  
Vincenzo Molinari ◽  
Domiziano Mostacci ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Plasma Focus ◽  
Reaction Rates ◽  
Experimental Production ◽  
Endogenous Production ◽  
The Us ◽  
Further Development ◽  
Radio Isotopes ◽  
Very High

In recent years, research conducted in the US and in Italy has demonstrated production of radioisotopes in plasma focus devices, and particularly, on what could be termed "endogenous" production, to wit, production within the plasma it self, as opposed to irradiation of tar gets. This technique relies on the formation of localized small plasma zones characterized by very high densities and fairly high temperatures. The conditions prevailing in these zones lead to high nuclear reaction rates, as pointed out in previous work by several authors. Further investigation of the cross sections involved has proven necessary to model the phenomena involved. In this paper, the present status of research in this field is re viewed, both with regards to cross section models and to experimental production of radio isotopes. Possible out comes and further development are discussed.

scholarly journals Investigation of the Warping Torsion of a Press Machine

2020 ◽  
Vol 15 (3) ◽  
pp. 150-161
Author(s):  
Antal Gábor Erdős ◽  
Károly Jármai
Keyword(s):  
Normal Stress ◽  
Cross Section ◽  
Torsional Stress ◽  
Very High ◽  
Open Cross Section

In this article, the investigation of a press machine with 30 tons of pressing weight is presented. The beam of this machine is an I-beam, which has an open cross-section. It is known that this version of cross-section is sensitive to torsional stress. The stress from warping torsion is normal stress, so the opened cross-section is more sensitive to this type of stress. The bimoment that causes normal stress can also be very high, so dealing with this stress is very important.

scholarly journals Sizing of Refractory Castable Gas-Burner Using Thermomechanical Simulations

2010 ◽  
Vol 70 ◽  
pp. 173-178
Author(s):  
Fabien Nazaret ◽  
Thierry Cutard ◽  
Olivier Barrau
Keyword(s):  
Damage Model ◽  
Peak Stress ◽  
Internal Length ◽  
Damage Level ◽  
Refractory Castables ◽  
Before And After ◽  
Tension And Compression ◽  
Material Choice ◽  
Gas Burner ◽  
Refractory Structures

Damage is a crucial characteristic of refractory castables and has to be considered to simulate correctly the behaviour of refractory structures. But, damage modelling by finite element simulations remains difficult. Indeed, the use of a continuum damage model with softening leads to strain localization phenomena. Numerical results depend on the mesh. Several numerical methods allow solving this meshing dependence by introducing an internal length in the material constitutive laws. In this paper, a regularization method has been applied with the damage plasticity model, considering a scalar value for damage. This model enables to take into account permanent strains due to plasticity and damage before and after the peak stress in tension and compression. Thermomechanical simulations are performed with this model to predict damage in a gas-burner. The damage level is evaluated after a thermal simulation generating high temperature gradients. Interests to take into account damage in the refractory structures are discussed. Sensitivity of results to material properties is studied. This work gives an example of using thermomechanical simulations to improve the design of refractory castable structures and to help in the material choice.

Very High Cycle Fatigue Testing under Spectrum Loading for Endurance Limit Structural Design

2020 ◽  
Vol 65 (1) ◽  
pp. 1-7
Author(s):  
David T. Rusk ◽  
Robert E. Taylor ◽  
Bruce A. Pregger ◽  
Luis J. Sanchez
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Crack Nucleation ◽  
Peak Stress ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

A program has recently concluded that generated fatigue test data for the influence of a rotorcraft main rotor blade root bending spectrum (Helix) on the crack nucleation mechanisms in 7075-T651 aluminum. High-frequency tests were performed that generated spectrum fatigue failures out to nearly 109 cycles. Fractographic examination showed a distinct change in crack nucleation from slip initiated to inclusion-initiated cracking as the spectrum peak stress level was increased. Spectrum life predictions were made using three different baseline constant-amplitude S-N curves, one using a traditional rotorcraft original equipment manufacturer fitting methodology, one using the high-cycle fatigue (HCF) portion of a strainlife curve, and one that was fitted to S-N data with test lives out to 3×108 cycles. The spectrum life prediction using the S-N curve that properly modeled material behavior in the very high cycle fatigue regime provided a good correlation to the spectrum fatigue test data. Predictions using the other S-N curves were highly conservative.

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