Elastic-Plastic Buckling of Internally Pressurized Thin Torispherical Shells

1979 ◽  
Vol 101 (3) ◽  
pp. 216-225 ◽  
Author(s):  
G. D. Galletly ◽  
S. K. Radhamohan
Keyword(s):  
Strain Hardening ◽  
Material Properties ◽  
Parametric Study ◽  
Geometric Parameters ◽  
Plastic Buckling ◽  
Elastic Plastic ◽  
Hardening Coefficient ◽  
Approximate Formulas

The elastic-plastic buckling of internally pressurized torispherical shells is considered in some detail in the paper. The effects of geometric parameters (r/D, RS/D and D/t) and material properties (σyp, E and the strain-hardening coefficient) on the elastic-plastic internal buckling pressures were investigated using the BOSOR 5 program. Based on the results of the parametric study, approximate formulas for predicting the elastic-plastic internal buckling pressures are suggested. These should be useful to designers.

Plastic Collapse of Thin Internally Pressurized Torispherical Shells

1979 ◽  
Vol 101 (4) ◽  
pp. 311-320 ◽  
Author(s):  
S. K. Radhamohan ◽  
G. D. Galletly
Keyword(s):  
Strain Hardening ◽  
Yield Stress ◽  
Material Properties ◽  
Parametric Study ◽  
Companion Paper ◽  
Experimental Results ◽  
Plastic Collapse ◽  
Approximate Design ◽  
Mode Of Failure ◽  
Hardening Coefficient

The plastic collapse pressures of internally pressurized thin torispherical shells are given in the present paper. The influence of both the geometric parameters (i.e., r/D, RS/D and D/t) and the material properties (yield stress σyp and the strain-hardening coefficient) on the plastic collapse pressures were investigated. Both steel and aluminium shells were analyzed and, based on the present parametric study, approximate design equations for calculating the plastic collapse pressures are suggested. The asymmetric buckling pressures, pcr, for torispherical shells (obtained from a companion paper) are also compared with the plastic collapse pressures, pc, to determine which are the lower and, thus, control the mode of failure. In addition, the approximate design equations for pcr and pc are compared with some experimental results on small machined models; the agreement between theory and test was quite good.

scholarly journals Relationship Between Rockwell C Hardness and Inelastic Material Constants

2002 ◽  
Vol 124 (2) ◽  
pp. 179-184 ◽  
Author(s):  
Akihiko Hirano ◽  
Masao Sakane ◽  
Naomi Hamada
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Strain Hardening ◽  
Yield Stress ◽  
Plastic Material ◽  
Stress And Strain ◽  
Material Constants ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Hardening Coefficient

This paper describes the relationship between Rockwell C hardness and elastic-plastic material constants by using finite element analyses. Finite element Rockwell C hardness analyses were carried out to study the effects of friction coefficient and elastic-plastic material constants on the hardness. The friction coefficient and Young’s modulus had no influence on the hardness but the inelastic materials constants, yield stress, and strain hardening coefficient and exponent, had a significant influence on the hardness. A new equation for predicting the hardness was proposed as a function of yield stress and strain hardening coefficient and exponent. The equation evaluated the hardness within a ±5% difference for all the finite element and experimental results. The critical thickness of specimen and critical distance from specimen edge in the hardness testing was also discussed in connection with JIS and ISO standards.

Buckling Strength of Pressurized Cylindrical Shells under Axial Compression

2014 ◽  
Vol 638-640 ◽  
pp. 1750-1753
Author(s):  
Yu Chao Zheng ◽  
Yang Yan ◽  
Pei Jun Wang
Keyword(s):  
Numerical Simulation ◽  
Internal Pressure ◽  
Axial Compression ◽  
Parametric Study ◽  
Shell Thickness ◽  
Steel Shell ◽  
Plastic Buckling ◽  
Buckling Strength ◽  
Elastic Plastic ◽  
Steel Strength

A systematic parametric study was carried out to investigate the elastic and elastic-plastic buckling behaviors of imperfect steel shell subject to axial compression and internal pressure. Studied parameters include the magnitude of internal pressure, steel strength, and ratio of cylinder radius to shell thickness. Design equations were proposed for calculating the elastic and elastic-plastic buckling strength of imperfect steel shells under combination of axial compression and internal pressure. The buckling strength predicated by proposed equations agrees well with that from the numerical simulation.

Elastic and Elastic-Plastic Buckling of Internally Pressurized 2:1 Ellipsoidal Shells

1978 ◽  
Vol 100 (4) ◽  
pp. 335-343 ◽  
Author(s):  
G. D. Galletly
Keyword(s):  
Strain Hardening ◽  
Linear Strain ◽  
Plastic Buckling ◽  
Elastic Plastic

Elastic and elastic-plastic buckling pressures for internally-pressurized 2:1 ellipsoidal shells with diameter-thickness ratios in the range 750 < D/t < 1500 are given in the paper. The effects of σyp, E and linear strain hardening on the buckling pressures were investigated and both flow and deformation theories utilized. Some experimental/theoretical correlations are also given. The elastic pcr’s differ from some which have been published recently and the elastic-plastic pcr’s are believed to be new. For steel shells, flow and deformation theories sometimes gave contradictory buckling predictions but this was not the case with the aluminum shells which were investigated.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 18. EXPERIMENTAL CHECK OF THEORETICAL RESULTS FOR DIFFERENT HOLLOW RADIUSES AND BOTTOM-MOST PART THICKNESSES

2020 ◽  
Vol 0 (9) ◽  
pp. 16-23
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Strain Hardening ◽  
Theoretical Calculations ◽  
High Accuracy ◽  
Geometric Parameters ◽  
Strength Characteristics ◽  
Experimental Check ◽  
Hardening Material ◽  
Direct Extrusion ◽  
Theoretical Results

The results of an experimental check of the obtained theoretical formulae allowing us to determine the most important parameters of extrusion cartridges with a counterpunch for different hollow radiuses and bottom-most part thicknesses are presented. Characteristics of used tools, geometric parameters of extrusion experiments, strength characteristics of deformed materials and lubricants are described in detail. Both strain-hardening material and strain-unhardening material were studied. Methodology of the theoretical calculations is demonstrated in detail. High accuracy of the obtained design formulae was confirmed.

Experimental and Three-Dimensional Finite Element Study of Scratch Test of Polymers at Large Deformations

2004 ◽  
Vol 126 (2) ◽  
pp. 372-379 ◽  
Author(s):  
J. L. Bucaille ◽  
E. Felder ◽  
G. Hochstetter
Keyword(s):  
Strain Hardening ◽  
Penetration Depth ◽  
Large Deformations ◽  
Numerical Study ◽  
Scratch Test ◽  
Scratch Resistance ◽  
Plastic Strains ◽  
Thermosetting Polymer ◽  
Scratch Tests ◽  
Hardening Coefficient

An experimental and numerical study of the scratch test on polymers near their surface is presented. The elastoplastic response of three polymers is compared during scratch tests at large deformations: polycarbonate, a thermosetting polymer and a sol-gel hard coating composed of a hybrid matrix (thermosetting polymer-mineral) reinforced with oxide nanoparticles. The experiments were performed using a nanoindenter with a conical diamond tip having an included angle of 30 deg and a spherical radius of 600 nm. The observations obtained revealed that thermosetting polymers have a larger elastic recovery and a higher hardness than polycarbonate. The origin of this difference in scratch resistance was investigated with numerical modelling of the scratch test in three dimensions. Starting from results obtained by Bucaille (J. Mat. Sci., 37, pp. 3999–4011, 2002) using an inverse analysis of the indentation test, the mechanical behavior of polymers is modeled with Young’s modulus for the elastic part and with the G’sell-Jonas’ law with an exponential strain hardening for the viscoplastic part. The strain hardening coefficient is the main characteristic parameter differentiating the three studied polymers. Its value is equal to 0.5, 4.5, and 35, for polycarbonate, the thermosetting polymer and the reinforced thermosetting polymer, respectively. Firstly, simulations reveals that plastic strains are higher in scratch tests than in indentation tests, and that the magnitude of the plastic strains decreases as the strain hardening increases. For scratching on polycarbonate and for a penetration depth of 0.5 μm of the indenter mentioned above, the representative strain is equal to 124%. Secondly, in agreement with experimental results, numerical modeling shows that an increase in the strain hardening coefficient reduces the penetration depth of the indenter into the material and decreases the depth of the residual groove, which means an improvement in the scratch resistance.

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