scholarly journals Modelling the Creep Curves of β-BOPP Film

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Wang Kejian
Keyword(s):  
Creep Curves

A modified θ projection model for constant load creep curves-II. Application of creep life prediction

2019 ◽  
Vol 35 (4) ◽  
pp. 687-694 ◽  
Author(s):  
Chao Fu ◽  
Yadong Chen ◽  
Xiaofei Yuan ◽  
Sammy Tin ◽  
Stoichko Antonov ◽  
...  
Keyword(s):  
Life Prediction ◽  
Constant Load ◽  
Creep Life ◽  
Projection Model ◽  
Creep Life Prediction ◽  
Creep Curves

Kinetic equations of creep and damage for description of materials with non-monotonic dependence of fracture strain on stress

2021 ◽  
Vol 23 (3) ◽  
pp. 139-154
Author(s):  
Inna Banshchikova ◽  
Keyword(s):  
Experimental Data ◽  
Comparative Analysis ◽  
Damage Accumulation ◽  
Elevated Temperatures ◽  
Fracture Strain ◽  
Least Squares Method ◽  
Kinetic Equations ◽  
Steel 12Kh18n10t ◽  
Static Mode ◽  
Creep Curves

Introduction. Reducing the level of damage accumulation during pressure treatment of materials at elevated temperatures in creep and close to superplasticity modes in the manufacture of parts can significantly increase its service life in the cold state. Finding temperature and power conditions leading to a reduction in damage of material during the production process and operation is an important task. The purposes of the work: 1) to show the possibility of using the Sosnin-Gorev creep and damage model for alloys with a non-monotonic dependence of strain at fracture on diagrams with creep curves; 2) to carry out comparative analysis of damage accumulation under conditions of uniaxial tension at constant stress and at constant strain rates for alloy with such a dependence. Research methods. Used scalar damage parameter is equated to the normalized deformation, i.e. to the ratio of the current strain to the fracture strain. To find the coefficients of relations creep and damage, the similarity of the creep curves in the normalized values “normalized strain – normalized time”, i.e. the presence of single normalized curve of damage accumulation is checked. The least squares method is used to approximate the experimental data. Numerical integration methods are used for comparative analysis of deformation modes. Results and discussion. Determination of the parameters of the creep and damage equations by the method of a single normalized curve is carried out on the example of experimental data for steel 12Kh18N10T (12Cr18Ni10Ti) at 850 °C, which has a minimum of fracture strain in diagrams with creep curves. Analysis of the static and kinematic modes of deformation for studied material showed that damage accumulation in both cases is practically the same for stresses close to the stress at which this minimum is reached. If the stresses are lower, then the lower level of damage accumulation will be in the kinematic mode; if the stresses above the minimum value, then the static mode will lead to a lower level of damage accumulation. Application. The obtained results can be useful when choosing rational modes of forming structural elements from alloys with a non-monotonic dependence of the fracture strain on stress, as well as in evaluating it for long-term strength during operation.

High-Temperature Failures

2012 ◽  
pp. 415-459
Keyword(s):  
High Temperature ◽  
Stress Rupture ◽  
Creep Life Prediction ◽  
Creep Curves ◽  
Creep Fatigue ◽  
Temperature Fracture ◽  
Underlying Mechanisms ◽  
Thermomechanical Damage ◽  
Stress Rupture Testing ◽  
Related Design

Abstract This chapter compares and contrasts the high-temperature behaviors of metals and composites. It describes the use of creep curves and stress-rupture testing along with the underlying mechanisms in creep deformation and elevated-temperature fracture. It also discusses creep-life prediction and related design methods and some of the factors involved in high-temperature fatigue, including creep-fatigue interaction and thermomechanical damage.

Nonlinear Damage Creep Model of Coal or Rock Containing Gas

2012 ◽  
Vol 204-208 ◽  
pp. 289-296
Author(s):  
Xiao Bin Yang ◽  
Yang Li ◽  
Hai He Guan ◽  
Tian Yang Li ◽  
Jie Shan He
Keyword(s):  
Gas Absorption ◽  
Creep Model ◽  
Creep Experiment ◽  
Creep Equation ◽  
Stick Slip ◽  
Kelvin Model ◽  
Creep Properties ◽  
Material Parameters ◽  
Whole Process ◽  
Creep Curves

In order to study the creep properties of coal or rock containing gas, the creep properties of coal or rock without gas were studied firstly. Through analyzing the previous creep experiment results of coal or rock, one nonlinear damage creep model of coal or rock was founded based on the general Kelvin model. In this model, assumed that the damage is a function of stress level and time, and introduced one nonlinear hardened function into the general Kelvin model, the nonlinear damage fading creep equation and the nonlinear damage creep whole process equation were obtained. Besides this model, considering the composite structure of coal or rock, gas and gas absorption layer, and assuming that this structure has the stick-slip property under the outside load, so a stick-slip module was added in the general Kelvin model and a new nonlinear damage creep model of coal or rock containing gas was founded. Given the value of the material parameters in the two equations, the creep curves varied with the time were drawn under different axial compression. Through the theoretical curves, the nonlinear damage creep model in this paper was proved to be rational.

Study of the Effects of High Temperatures on the Engineering Properties of Steel 42CrMo4

2015 ◽  
Vol 34 (1) ◽  
Author(s):  
Josip Brnic ◽  
Goran Turkalj ◽  
Marko Canadija ◽  
Domagoj Lanc ◽  
Marino Brcic
Keyword(s):  
Experimental Data ◽  
Impact Energy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Charpy Impact ◽  
Engineering Properties ◽  
Charpy Impact Energy ◽  
Rheological Models ◽  
Creep Curves ◽  
Low Levels

AbstractThe paper presents and analyzes the experimental results of the effect of elevated temperatures on the engineering properties of steel 42CrMo4. Experimental data relating to the mechanical properties of the material, the creep resistance as well as Charpy impact energy. Temperature dependence of the mentioned properties is also shown. Some of creep curves were simulated using rheological models and an analytical equation. Finally, an assessment of fracture toughness was made that was based on experimentally determined Charpy impact energy. Based on the obtained results it is visible that the tensile strength (617 MPa) and yield strength (415 MPa) have the highest value at the room temperature while at the temperature of 700 °C (973 K) these values significantly decrease. This steel can be considered resistant to creep at 400 °C (673 K), but at higher temperatures this steel can be subjected to low levels of stress in a shorter time.

Application of Hypotheses Theory during Creep Curves Assesment

2017 ◽  
Vol 1142 ◽  
pp. 367-370
Author(s):  
Martin Reznicek ◽  
Lenka Hylova ◽  
Michal Stanek ◽  
Martin Ovsik
Keyword(s):  
Creep Test ◽  
Confidence Level ◽  
Subjective Assessment ◽  
Measured Data ◽  
Whitney Test ◽  
Current State ◽  
Mann Whitney Test ◽  
Creep Curves

This article is focused on a test assesment with a low repeatability, which is typical of its financial and time severity. In the introduction of this work the assessment of the current state of the solved problem concentrated on the creep test assesment is carried out, which is typical of its low repeatability. These results are subsequently graphically confronted with the subjective assessment of the observer and using Mann-Whitney test. This test is there used for finding if measured data come from the same basic file or come from the selected confidence level. The results show the significance of using this test, which is calculated with certain probability.

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