Determination of the multi-axial stress creep fracture criterion using a modified tensile creep unit

1977 ◽  
Vol 4 (1) ◽  
pp. 296-300 ◽  
Author(s):  
J. Henderson ◽  
F. R. Ferguson
Keyword(s):  
Fracture Criterion ◽  
Axial Stress ◽  
Tensile Creep ◽  
Creep Fracture

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

Investigation of Residual Stress Development During Swage Autofrettage, Using Finite Element Analysis

2009 ◽  
Author(s):  
Michael C. Gibson ◽  
Amer Hameed ◽  
John G. Hetherington
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Axial Stress ◽  
Slope Angle ◽  
Subsequent Development ◽  
Element Model ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Reverse Yielding

Swaging is one method of autofrettage, a means of pre-stressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed through the tube. A Finite Element model of the swaging process was developed, in ANSYS, and systematically refined, to investigate the mechanism of deformation and subsequent development of residual stresses. A parametric study was undertaken, of various properties such as mandrel slope angle, parallel section length and friction coefficient. It is observed that the axial stress plays a crucial role in the determination of the residual hoop stress and reverse yielding. The model, and results obtained from it, provides a means of understanding the swaging process and how it responds to different parameters. This understanding, coupled with future improvements to the model, potentially allows the swaging process to be refined, in terms of residual stresses development and mandrel driving force.

The Effect of Specimen Size on the Determination of Residual Stress in Polymer Pipe Wall

2014 ◽  
Vol 627 ◽  
pp. 141-144 ◽  
Author(s):  
Jan Poduška ◽  
Jaroslav Kučera ◽  
Pavel Hutař ◽  
Martin Ševčík ◽  
J. Křivánek ◽  
...  
Keyword(s):  
Residual Stress ◽  
Axial Stress ◽  
Three Dimensional ◽  
Axial Direction ◽  
Polymer Materials ◽  
Axial Residual Stress ◽  
Axial Dimension ◽  
Measured Deformation ◽  
Different Dimensions

As a result of the production process, there are axial and tangential residual stresses present in pressure pipes made of polymer materials such as polyethylene or polypropylene. The residual stress magnitude and distribution have a significant influence on the pipe lifetime. In this contribution the results from experiments focused on determining the tangential residual stress distribution in the walls of polypropylene pipes of different dimensions are compared. The experimental method used involves measuring the deformation of ring shaped specimens that were slit in the axial direction. Measured deformation of the ring specimen is a result of the tangential and axial stress superposition. However, the effect of the axial residual stress depends on the specimen axial dimension and tangential residual stress estimated basing on experimental data should be corrected according to axial dimension of the specimen used. The correction suggested in this article is determined based on three-dimensional FEM simulations of the experiment.

scholarly journals Using DEFORM Software for Determination of Parameters for Two Fracture Criteria on DIN 34CrNiMo6

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 445
Author(s):  
Ivana Poláková ◽  
Michal Zemko ◽  
Martin Rund ◽  
Ján Džugan
Keyword(s):  
Fracture Criterion ◽  
Damage Model ◽  
Material Model ◽  
Mechanical Tests ◽  
Fracture Criteria ◽  
Stress States ◽  
Determination Of Parameters ◽  
Accuracy Of Prediction ◽  
Good Agreement

The aim of this study was to calibrate a material model with two fracture criteria that is available in the DEFORM software on DIN 34CrNiMo6. The purpose is to propose a type of simple test that will be sufficient for the determination of damage parameters. The influence of the quantity of mechanical tests on the accuracy of the fracture criterion was explored. This approach was validated using several tests and simulations of damage in a tube and a round bar. These tests are used in engineering applications for their ease of manufacturing and their strong ability to fracture. The prediction of the time and location of the failure was based on the parameters of the relevant damage model. Normalized Cockroft-Latham and Oyane criteria were explored. The validation involved comparing the results of numerical simulation against the test data. The accuracy of prediction of fracture for various stress states using the criteria was evaluated. Both fracture criteria showed good agreement in terms of the fracture locus, but the Oyane criterion proved more suitable for cases covering larger triaxiality ranges.

Cycle-Dependent and Time-Dependent Bone Fracture With Repeated Loading

1983 ◽  
Vol 105 (2) ◽  
pp. 166-170 ◽  
Author(s):  
D. R. Carter ◽  
W. E. Caler
Keyword(s):  
Low Cycle Fatigue ◽  
Strain Range ◽  
Creep Damage ◽  
Cyclic Strain ◽  
Fatigue Tests ◽  
Time Dependent ◽  
Tensile Creep ◽  
Repeated Loading ◽  
Time To Failure ◽  
Creep Fracture

Fatigue tests of human cortical bone (up to 1.74 × 106 cycles) were conducted under tension-compression (T-C) and zero-tension (O-T) modes with a 2Hz, stress controlled, sinusoidal loading history. Tensile creep-fracture tests at constant stress levels were also performed. The relationship between the initial cyclic strain range and cycles to failure with the T-C specimens were consistent with that derived previously in low-cycle fatigue under strain control. Using a time-dependent failure model, the creep-fracture data was found to be consistent with previous studies of the influence of strain rate on the monotonic tensile strength of bone. The model also predicted quite well the time to failure for the O-T fatigue specimens, suggesting that creep damage plays an important role in O-T fatigue specimens.

An approach for the determination of the preconsolidation pressure in sensitive clays

1980 ◽  
Vol 17 (3) ◽  
pp. 446-453 ◽  
Author(s):  
S. Leroueil ◽  
J. P. LeBihan ◽  
F. Tavenas
Keyword(s):  
Pore Pressure ◽  
Theoretical Basis ◽  
Axial Stress ◽  
New Method ◽  
One Stage ◽  
Preconsolidation Pressure ◽  
Constant Rate ◽  
Constant Gradient ◽  
Oedometer Tests

The present methods for the determination of the preconsolidation pressure of clays are time consuming and expensive. A new method is proposed in which the clay is loaded in a "one-stage loading" to an axial stress in excess of the estimated preconsolidation pressure. The preconsolidation pressure is determined from the observation of the pore pressure dissipation within a few hours. The theoretical basis of this method is also used to discuss the method of interpreting constant rate of strain and constant gradient oedometer tests.

Combined Axial Stress Fatigue Reliability for AISI 4130 and 4340 Steels

1976 ◽  
Vol 98 (1) ◽  
pp. 153-160 ◽  
Author(s):  
D. B. Kececioglu ◽  
L. B. Chester
Keyword(s):  
Axial Stress ◽  
Probabilistic Design ◽  
Fatigue Reliability ◽  
Combined Stress ◽  
Design Data ◽  
Mechanical Parts ◽  
Improved Design ◽  
Aisi 4130 ◽  
Stress Fatigue

The failure-governing strength distributions of round specimens are determined. These are subjected to a mean tensile axial stress onto which alternating tensile and compressive axial stresses are superimposed. The AISI 4340 steel specimens are tested for a life of 106 cycles and the AISI 4130 steel specimens for 2 × 106 cycles. Distributional Goodman diagrams are developed and various combined-stress theories are compared with the experimental results. The application of the probabilistic “Design-for-Reliability” methodology utilizing these design data is illustrated by two examples. This methodology leads to improved design and to the determination of the reliability of mechanical parts and components subjected to such combined axial fatigue loads.

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