An Experimental Investigation of Yield Surfaces and Loading Surfaces of Pure Aluminum With Stress-Controlled and Strain-Controlled Paths of Loading

1984 ◽  
Vol 106 (4) ◽  
pp. 349-354 ◽  
Author(s):  
Aris Phillips ◽  
Wei-yang Lu
Keyword(s):  
Experimental Investigation ◽  
Stress Relaxation ◽  
Plastic Strain ◽  
Pure Aluminum ◽  
Testing Machine ◽  
Combined Stress ◽  
Computer Controlled ◽  
Yield Surfaces

Tension-torsion tests with a computer controlled servohydraulic testing machine are reported. Yield surfaces were obtained during a load controlled path, which includes combined stress creep, as well as during a strain controlled path, which includes combined stress relaxation. These surfaces and their relation to the corresponding loading surfaces is discussed. The development of plastic strain increments and their relation to the yield surfaces and loading surfaces is also discussed.

An experimental investigation of the initial and subsequent yield surfaces of 40Kh steel

1983 ◽  
Vol 15 (11) ◽  
pp. 1590-1595 ◽  
Author(s):  
A. V. Troshchenko ◽  
N. M. Kul'chitskii
Keyword(s):  
Experimental Investigation ◽  
40Kh Steel ◽  
Yield Surfaces

scholarly journals On Computational Modelling Of Strain-Hardening Material Dynamics

2012 ◽  
Vol 11 (5) ◽  
pp. 1525-1546 ◽  
Author(s):  
Philip Barton ◽  
Evgeniy Romenski
Keyword(s):  
Relaxation Time ◽  
Stress Relaxation ◽  
Plastic Strain ◽  
Strain Hardening ◽  
Three Dimensional ◽  
Computational Modelling ◽  
Constitutive Models ◽  
Successful Implementation ◽  
Hardening Material ◽  
Dislocation Mechanics

AbstractIn this paper we show that entropy can be used within a functional for the stress relaxation time of solid materials to parametrise finite viscoplastic strain-hardening deformations. Through doing so the classical empirical recovery of a suitable irreversible scalar measure of work-hardening from the three-dimensional state parameters is avoided. The success of the proposed approach centres on determination of a rate-independent relation between plastic strain and entropy, which is found to be suitably simplistic such to not add any significant complexity to the final model. The result is sufficiently general to be used in combination with existing constitutive models for inelastic deformations parametrised by one-dimensional plastic strain provided the constitutive models are thermodynamically consistent. Here a model for the tangential stress relaxation time based upon established dislocation mechanics theory is calibrated for OFHC copper and subsequently integrated within a two-dimensional moving-mesh scheme. We address some of the numerical challenges that are faced in order to ensure successful implementation of the proposedmodel within a hydrocode. The approach is demonstrated through simulations of flyer-plate and cylinder impacts.

FINITE ELEMENT ANALYSIS OF CONSTRAINED GROOVE PRESSING OF PURE ALUMINUM SHEETS

2013 ◽  
Vol 02 (01) ◽  
pp. 1350001 ◽  
Author(s):  
S. S. SATHEESH KUMAR ◽  
I. BALASUNDAR ◽  
T. RAGHU
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Deformation Behavior ◽  
Strain Distribution ◽  
Pure Aluminum ◽  
Detailed Examination ◽  
Deformation Characteristics ◽  
Element Analysis ◽  
Aluminum Sheets

Constrained groove pressing (CGP) is an attractive severe plastic deformation technique capable of processing ultrafine grained/nanostructured sheet materials. The deformation behavior of pure aluminum during constrained groove pressing is investigated by carrying out a two-dimensional finite element analysis (FEA). FEA predicted deformation behavior observed during each stages of pressing indicated almost negligible deformation in flat regions, whereas the inclined shear regions revealed diverse deformation characteristics. The plastic strain distributions unveiled inhomogeneous strain distribution at the end of one pass. Detailed examination of plastic strain evolution during CGP along various sections divulged superior strain distribution along middle surfaces when compared to top and bottom surfaces. The degree of strain homogeneity is evaluated quantitatively along different regions of the sheet and is correlated to the deformation characteristics. Load–stroke characteristics obtained during corrugating and flattening of sheets exhibited three stages and two stages behavior, respectively. The results obtained from the analysis are experimentally validated by processing pure aluminum sheets by CGP and the measured deformation homogeneity is benchmarked with FEA results.

Experimental Investigation and Finite Element Analysis of the Inversion of Capped End Frusta as Impact Energy Absorbers

2004 ◽  
Author(s):  
A. A. N. Aljawi ◽  
A. A. A. Alghamdi ◽  
T. M. N. Abu-Mansour
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Testing Machine ◽  
Dynamic Test ◽  
Element Analysis ◽  
Static Tests ◽  
Qualitative Dynamic ◽  
Finite Element Package ◽  
Energy Absorbers ◽  
Deformation Modes

In this paper, an innovative mode of deformation of the frusta is presented and discussed in details. A full experimental investigation for the quasi-static axial inversion of right circular frusta is given. The experimental work includes studying the effect of frusta wall thickness, angle of frusta and material type on the inversion of the frusta. The quasi-static tests were conducted on an Instron Universal testing machine and qualitative dynamic test were carried using Drop Hammer Facility. Finite element (FE) modeling of the inversion mode is carried out by using ABAQUS FE package. Analysis of the deformation modes is examined using a non-linear model of the finite element package. The FE findings are reported and modes of deformation during the inversion of aluminum frusta are described under quasi-static and dynamic cases. Furthermore, a good agreement is reported between the finite element force histories and the experimental results.

A COMPARATIVE STUDY OF STRESS RELAXATION RATE IN UNIRRADIATED AND IRRADIATED PURE TITANIUM AT LOW TEMPERATURES

2007 ◽  
Vol 21 (31) ◽  
pp. 5247-5255 ◽  
Author(s):  
I. M. GHAURI ◽  
KARRAR HAIDER ◽  
NAVEED AFZAL ◽  
S. A. SIDDIQUE
Keyword(s):  
Stress Relaxation ◽  
Relaxation Rate ◽  
Testing Machine ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Temperature Range ◽  
Radiation Induced ◽  
Mechanical Twins ◽  
Induced Defects ◽  
The Given

Stress relaxation rate in unirradiated and electron-beam-irradiated polycrystalline titanium (99.994%) was studied in the temperature range 300–100 K. Titanium specimens were irradiated with 12 MeV electrons to a dose of 0.01 dpa for 12 min. at 300 K. Tensile tests of the specimens were performed using a Universal Testing Machine in the given temperature range. To measure the relaxation of stress with time, the crosshead of the machine was arrested at different fixed loads. Stress relaxation rate s for a given stress level σ0 was found to be temperature dependent, i.e., it decreased with decreasing temperature both in unirradiated and irradiated specimens. However, the decrease was more pronounced in irradiated specimens than that of unirradiated ones. The observed decrease in s values with decrease in temperature is ascribed to the retarding effect of unrelaxed dislocations pinned at defects, especially at the twin boundaries in the course of deformation, which became more conspicuous in irradiated specimens due to the interaction of glide dislocations with radiation-induced defects, in addition to mechanical twins. The activation energy for the movement of dislocations, calculated using the single-barrier model of stress relaxation, was found to be higher in irradiated specimens than that of unirradiated ones at all test temperatures.

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