scholarly journals Influence of Normal Stress on Creep in Tension and Compression of Polyethylene and Rigid Polyvinyl Chloride Copolymer

1962 ◽  
Vol 84 (2) ◽  
pp. 237-246 ◽  
Author(s):  
D. G. O’Connor ◽  
W. N. Findley
Keyword(s):  
Normal Stress ◽  
Polyvinyl Chloride ◽  
Material Structure ◽  
Reasonable Accuracy ◽  
Creep Tests ◽  
Compression Creep ◽  
Cent Relative Humidity ◽  
Tension And Compression ◽  
New Apparatus ◽  
Shear Planes

New apparatus suitable for compression creep tests of slender specimens is described. The apparatus is designed to prevent buckling and to introduce a minimum of friction. Results are reported for tension and compression creep of polyethylene and annealed, unplasticized polyvinyl chloride copolymer at 75 deg F and 50 per cent relative humidity. The stress σ, strain ε, time t data from these tests were found to be describable with reasonable accuracy by the equation ε=ε0′sinhσ/σε+m′tnsinhσ/σm where ε0′, m′, n, σε, and σm are material constants. The results for polyethylene show that the creep in tension and compression were virtually the same. However, the creep in tension was similar but larger than in compression for polyvinyl chloride. These observations are interpreted in terms of the material structure and the influence of the normal stress on active shear planes.

scholarly journals High Temperature Behavior of Al-7Si-0.4Mg Alloy with Er and Zr Additions

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 879
Author(s):  
Elisabetta Gariboldi ◽  
Chiara Confalonieri ◽  
Marco Colombo
Keyword(s):  
High Temperature ◽  
Eutectic Silicon ◽  
A356 Alloy ◽  
Minor Element ◽  
High Temperature Strength ◽  
Creep Tests ◽  
Casting Alloys ◽  
Compression Creep ◽  
Tension And Compression

In recent years, many efforts have been devoted to the development of innovative Al-based casting alloys with improved high temperature strength. Research is often oriented to the investigation of the effects of minor element additions to widely diffused casting alloys. The present study focuses on Al-7Si-0.4Mg (A356) alloy with small additions of Er and Zr. Following previous scientific works on the optimization of heat treatment and on tensile strength, creep tests were carried out at 300 °C under applied stress of 30 MPa, a reference condition for creep characterization of innovative high-temperature Al alloys. The alloys containing both Er and Zr displayed a lower minimum creep strain rate and a longer time to rupture. Fractographic and microstructural analyses on crept and aged specimens were performed to understand the role played by eutectic silicon, by the coarse intermetallics and by α-Al matrix ductility. The creep behavior in tension of the three alloys has been discussed by comparing them to tension and compression creep curves available in the literature for Al-7Si-0.4Mg improved by minor elemental additions.

scholarly journals Experimental Investigation of the Tension and Compression Creep Behavior of Alumina-Spinel Refractories at High Temperatures

Ceramics ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 372-383
Author(s):  
Lucas Teixeira ◽  
Soheil Samadi ◽  
Jean Gillibert ◽  
Shengli Jin ◽  
Thomas Sayet ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Working Life ◽  
Refractory Materials ◽  
Secondary Creep ◽  
Inverse Identification ◽  
Creep Tests ◽  
Identification Procedure ◽  
Compression Creep ◽  
Experimental Creep ◽  
Tension And Compression

Refractory materials are subjected to thermomechanical loads during their working life, and consequent creep strain and stress relaxation are often observed. In this work, the asymmetric high temperature primary and secondary creep behavior of a material used in the working lining of steel ladles is characterized, using uniaxial tension and compression creep tests and an inverse identification procedure to calculate the parameters of a Norton-Bailey based law. The experimental creep curves are presented, as well as the curves resulting from the identified parameters, and a statistical analysis is made to evaluate the confidence of the results.

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 2904-2909 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Petr Král ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Room Temperature ◽  
Creep Behaviour ◽  
Coarse Grained ◽  
Pure Aluminium ◽  
Creep Tests ◽  
Angular Pressing ◽  
Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models

2018 ◽  
Vol 89 (8) ◽  
pp. 1472-1487
Author(s):  
Krzysztof Zerdzicki ◽  
Pawel Klosowski ◽  
Krzysztof Woznica
Keyword(s):  
Polyvinyl Chloride ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Material Models ◽  
Material Parameters ◽  
Coated Fabric ◽  
Coated Fabrics ◽  
Term Creep

In this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have been conducted: uniaxial tensile, biaxial tensile and long-term creep tests. The obtained results have been used for the parameter identification of the piecewise non-linear, Burgers and Bodner–Partom models. Next, the analysis of the influence of environmental conditions on the parameters of these models has been made. It has been concluded that some parameters are more and the others are less sensitive to the exposure to environmental and mechanical conditions. The change of material parameters for fill threads (due to larger deformation) is higher. The obtained results may be useful in the durability evaluation of the textile membranes reinforced with polyester threads and PVC coated. All the constitutive models with the identified parameters may be used for the numerical analysis of structures made of fabrics at the service beginning and after long-term usage.

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