Selection of optimum specimen shape for compression tests on brittle materials. II

1979 ◽  
Vol 11 (4) ◽  
pp. 438-443
Author(s):  
A. L. Kvitka ◽  
I. I. D'yachkov
Keyword(s):  
Brittle Materials ◽  
Compression Tests ◽  
Optimum Specimen ◽  
Specimen Shape ◽  
Selection Of

Tensile Testing at Low Temperatures

2004 ◽  
pp. 239-249
Keyword(s):  
Low Temperatures ◽  
Tensile Testing ◽  
Fiber Reinforced Polymer ◽  
Compression Tests ◽  
Test Procedures ◽  
Safety Issues ◽  
Reinforced Polymer ◽  
Engineering Materials ◽  
Temperature Test ◽  
Selection Of

Abstract This chapter details low-temperature test procedures and equipment. It discusses the role temperature plays in the properties of typical engineering materials. The effect that lowering the temperature of a solid has on the mechanical properties of a material is summarized for three principal groups of engineering materials: metals, ceramics, and polymers (including fiber-reinforced polymer). The chapter describes the factors that influence the selection of tensile testing, along with a comparison of tensile and compression tests. It covers the parameters and standards related to tensile testing. The chapter discusses the factors involved in controlling test temperature. Finally, the chapter discusses the safety issues concerning the use of cooled methanol, liquid-nitrogen, and liquid helium.

scholarly journals Fracture Property of Y-Shaped Cracks of Brittle Materials under Compression

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoyan Zhang ◽  
Zheming Zhu ◽  
Hongjie Liu
Keyword(s):  
Numerical Models ◽  
Brittle Materials ◽  
Test Results ◽  
Compression Tests ◽  
True Triaxial ◽  
Absolute Value ◽  
Branch Angle ◽  
Shaped Crack ◽  
Abaqus Code ◽  
Branch Crack

In order to investigate the properties of Y-shaped cracks of brittle materials under compression, compression tests by using square cement mortar specimens with Y-shaped crack were conducted. A true triaxial loading device was applied in the tests, and the major principle stresses or the critical stresses were measured. The results show that as the branch angleθbetween the branch crack and the stem crack is 75°, the cracked specimen has the lowest strength. In order to explain the test results, numerical models of Y-shaped cracks by using ABAQUS code were established, and the J-integral method was applied in calculating crack tip stress intensity factor (SIF). The results show that when the branch angleθincreases, the SIFKIof the branch crack increases from negative to positive and the absolute valueKIIof the branch crack first increases, and asθis 50°, it is the maximum, and then it decreases. Finally, in order to further investigate the stress distribution around Y-shaped cracks, photoelastic tests were conducted, and the test results generally agree with the compressive test results.

Acoustic Emissions at High and Low Frequencies During Compression Tests in Brittle Materials

Strain ◽  
2010 ◽  
Vol 47 ◽  
pp. 105-110 ◽  
Author(s):  
A. Schiavi ◽  
G. Niccolini ◽  
P. Tarizzo ◽  
A. Carpinteri ◽  
G. Lacidogna ◽  
...  
Keyword(s):  
Brittle Materials ◽  
Acoustic Emissions ◽  
Compression Tests ◽  
Low Frequencies

Minimization of Friction Influence on the Evaluation of Rheological Parameters From Compression Test: Application to a Forging Steel Behavior Identification

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
S. Diot ◽  
D. Guines ◽  
A. Gavrus ◽  
E. Ragneau
Keyword(s):  
Compression Test ◽  
Dynamic Compression ◽  
Element Model ◽  
Constitutive Law ◽  
Rheological Parameters ◽  
Mathematical Form ◽  
Compression Tests ◽  
Compressive Test ◽  
Test Application ◽  
Specimen Shape

In order to characterize the metal behavior at strain, strain rate, and temperature range encountered in metal forming processes, the rheological compressive test is well adapted and has been often used. Nevertheless, this experimental test is more complicated to realize than the extension one and requires some particular considerations owing to the friction condition occurring between the specimen and the dies. This paper deals with a new specimen shape proposed to realize both static and dynamic compression tests. The independence of the material parameters to die friction is highlighted by means of a pseudo-experimental validation. The proposed specimen shape is validated by compression tests carried out on a 50CD4 steel (norm EN 10 083). The choice of the mathematical form of the constitutive law allowing to characterize its behavior at strains, strain rates, and temperatures corresponding to an extrusion application is then discussed. To replicate more accurately the nonuniformity of the different fields in the specimen, a classical inverse procedure consisting in coupling a finite element model of the compression test with an optimization module is used to determined the rheological parameters.

scholarly journals On the Selection of an Appropriate Consolidation Coefficient for Offshore Geotechnical Design

2019 ◽  
Author(s):  
David White ◽  
Jinbo Chen ◽  
Susan Gourvenec ◽  
Conleth O’Loughlin
Keyword(s):  
Design Parameters ◽  
Compression Tests ◽  
Operating Life ◽  
Order Of Magnitude ◽  
Consolidation Coefficient ◽  
Consolidation Rate ◽  
Geotechnical Design ◽  
Strength And Stiffness ◽  
Selection Of ◽  
Changes In Soil Properties

Abstract This paper addresses the selection of an appropriate consolidation coefficient for the analysis of drainage beneath foundations and pipelines in offshore geotechnical design. An emerging trend in the design of subsea infrastructure is the consideration of ‘whole life’ effects — namely the changes in soil properties and geotechnical capacity over the operating life. Seabed pipelines that undergo repeated thermal expansion and contraction cause shearing and consolidation in the underlying soil, leading to significant changes in the available seabed friction. Also, foundations that are either fixed or designed to slide on the seabed, are subjected to intermittent loads interspersed with periods of consolidation. These also cause a change in seabed strength and geotechnical capacity. To assess the time over which these effects occur, and therefore their influence on the response and the reliability of the system, it is necessary to perform consolidation calculations, using an appropriate consolidation coefficient. This paper presents observed operative consolidation coefficients drawn from recent model testing measurements and numerical analyses. It is shown that the consolidation rate can vary by more than an order of magnitude for the same soil profile under different loading conditions, due to the differences in stiffness and permeability. Meanwhile, design parameters are commonly drawn from one-dimensional oedometer compression tests. This compendium of data highlights the potential variation in consolidation coefficient for different loading types and through the ‘whole life’ of infrastructure. A key conclusion is that consolidation effects generally occur faster than is commonly assumed, meaning that changes in strength and stiffness — that are commonly beneficial in design — may be more readily relied on than is done so in current practice.

A Methodology for the Evaluation of Mechanical Properties of Sausage Based on Tensile and Compression Tests

2005 ◽  
Vol 1 (3) ◽  
Author(s):  
Fabiane Guerra Daros ◽  
Sandro Campos Amico ◽  
Maria Lucia Masson
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Testing Machine ◽  
Food Product ◽  
Travel Speed ◽  
Compression Tests ◽  
Strain Behavior ◽  
Universal Testing ◽  
Section Shape ◽  
Specimen Shape

The food product called sausage is a meat emulsion in which the fat drops are dispersed in an aqueous matrix containing soluble proteins, other muscle components and conjunctive tissue. The rheological behavior of sausage needs to be known in order to monitor the quality and acceptance of this product and the evaluation of its response, for instance, to different packaging situations, which is a result of their stress-strain behavior when subjected to a particular static or dynamic stress. A methodology for the assessment of mechanical properties of sausage has been developed. A universal testing machine was used and tests were carried out in sausage available in the market to validate the methodology. Tensile and compression tests were carried out and test conditions were varied, including strain rate and specimen shape and temperature. The influence of the skin on the determinations was also assessed. The need to control cross-section shape was identified, and a dumb-bell and a cylinder specimen shape were proposed for tensile and compression tests, respectively. Temperature is critical and higher temperatures decrease tensile and compressive strengths. Sausage resistance is also sensitive to the strain rate, especially at low values. A travel speed of 50 mm/min seems to be appropriate since variations around this value did not affect tensile or compressive strength determinations. The presented methodology was found adequate to the intended objectives, producing reliable and reproductive results.

Cognitive gadgets and cognitive priors

2019 ◽  
Vol 42 ◽  
Author(s):  
Gian Domenico Iannetti ◽  
Giorgio Vallortigara
Keyword(s):  
Cognitive Neuroscience ◽  
Selection Of

Abstract Some of the foundations of Heyes’ radical reasoning seem to be based on a fractional selection of available evidence. Using an ethological perspective, we argue against Heyes’ rapid dismissal of innate cognitive instincts. Heyes’ use of fMRI studies of literacy to claim that culture assembles pieces of mental technology seems an example of incorrect reverse inferences and overlap theories pervasive in cognitive neuroscience.

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