Fundamental mechanical behaviors of dental restorative materials resin composites due to compressive and flexural loading and internal damage evaluation

2015 ◽  
Vol 26 (6) ◽  
pp. 826-839 ◽  
Author(s):  
Mamoru Mizuno
Keyword(s):  
Stress State ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Resin Composites ◽  
Compression Tests ◽  
Mechanical Behaviors ◽  
Stress Strain ◽  
Internal Damage ◽  
Bending Tests ◽  
Three Point Bending

Development of internal damage within resin composites was evaluated under compressive loading in order to predict crack initiation and fracture. Moreover, three-point bending tests were also carried out in order to clarify mechanical behavior and fracture under tensile stress state in comparison with those under compressive stress state. Both of them were conducted for the purpose of obtaining data to formulate constitutive equations for resin composites and to implement precise numerical simulation. Columnar specimens for compression tests and square pole specimens for three-point bending tests were prepared by using clinical resin composites. In compression tests, loading–unloading (or –reloading) was given to columnar specimens and Young’s modulus was evaluated by the gradient of stress–strain curves under unloading. Internal damage was evaluated from the variation of Young’s modulus as a scalar damage variable based on the continuum damage mechanics. The variation of apparent density and residual strain at vanished stress were also discussed in association with the development of internal damage. Accumulation of internal damage was found on the stress–strain curve under loading–unloading–reloading in comparison with the curve under monotonic loading. On the other hand, in three-point bending tests, dependence of stress–strain curves on light curing time and strain rate was clarified. Since compression tests have been carried out under similar experimental conditions by authors so far, mechanical behaviors of resin composites under tensile stress state were discussed in comparison with those under compressive stress state. Brittleness under tensile stress state was indicated in comparison with compressive stress state.

scholarly journals Stress–strain relationship model of glulam bamboo under axial loading

2020 ◽  
Vol 29 ◽  
pp. 2633366X2095872
Author(s):  
Yang Wei ◽  
Mengqian Zhou ◽  
Kunpeng Zhao ◽  
Kang Zhao ◽  
Guofen Li
Keyword(s):  
Tensile Stress ◽  
Compressive Stress ◽  
Failure Modes ◽  
Axial Loading ◽  
Tensile Failure ◽  
Stress Strain ◽  
Laminated Bamboo ◽  
Bamboo Scrimber ◽  
Strain Relationship ◽  
Strain Model

Glulam bamboo has been preliminarily explored for use as a structural building material, and its stress–strain model under axial loading has a fundamental role in the analysis of bamboo components. To study the tension and compression behaviour of glulam bamboo, the bamboo scrimber and laminated bamboo as two kinds of typical glulam bamboo materials were tested under axial loading. Their mechanical behaviour and failure modes were investigated. The results showed that the bamboo scrimber and laminated bamboo have similar failure modes. For tensile failure, bamboo fibres were ruptured with sawtooth failure surfaces shown as brittle failure; for compression failure, the two modes of compression are buckling and compression shear failure. The stress–strain relationship curves of the bamboo scrimber and laminated bamboo are also similar. The tensile stress–strain curves showed a linear relationship, and the compressive stress–strain curves can be divided into three stages: elastic, elastoplastic and post-yield. Based on the test results, the stress–strain model was proposed for glulam bamboo, in which a linear equation was used to describe the tensile stress–strain relationship and the Richard–Abbott model was employed to model the compressive stress–strain relationship. A comparison with the experimental results shows that the predicted results are in good agreement with the experimental curves.

Strain Capacity of X80 High-Strain Line Pipes

2007 ◽  
Author(s):  
Nobuhisa Suzuki ◽  
Joe Kondo ◽  
Nobuyuki Ishikawa ◽  
Mitsuru Okatsu ◽  
Junji Shimamura
Keyword(s):  
Compressive Stress ◽  
Axial Compression ◽  
Analytical Solutions ◽  
High Strain ◽  
Stress And Strain ◽  
Compression Tests ◽  
Geometric Imperfections ◽  
Bending Tests ◽  
Bending Capacity ◽  
Outside Diameter

Two compression tests and two bending tests of X80 high-strain line pipes were conducted to investigate the compression capacity and the bending capacity. The high-strain line pipes had the outside diameter of 762 mm (30”) and the D/t ratio of 49. The compression tests revealed that the pipes had the critical compressive strains of 0.90 and 0.78%. The bending tests of the pipes clarified that the 2D average critical compressive strains were 2.40 and 2.15% and the 1D average were 2.67 and 2.28%. The analytical solutions gave very fine predictions about the critical compressive stress and strain of the pipes subjected to axial compression. Based on the FEA results, while almost no effects of the geometric imperfections on the compression capacity were recognized, the effects of the geometric imperfections on the bending capacity were significant.

scholarly journals Report on laboratory tests of sandstone and porphyry for rock fracture analysis

2020 ◽  
Vol 19 (2) ◽  
pp. 087-100
Author(s):  
Jakub Gontarz ◽  
Jacek Szulej
Keyword(s):  
Tensile Strength ◽  
Rock Fracture ◽  
Strain Energy Release ◽  
Mechanical Tests ◽  
Bending Test ◽  
Compression Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Bending Of Beams ◽  
Brazilian Method

The paper presents the results of mechanical tests of three types of rocks from stone mines in Poland. Compression tests of cubic samples, three-point bending tests of beams, bending of beams with notch and testing of tensile strength using the quasi-Brazilian method were performed. Based on the tests, the compressive strength, tensile strength, Young's modulus, and Poisson's ratios were determined. The stress intensity factor and critical strain energy release rate in mode I were determined from the bending test of the notched beams. The determined values were used as parameters of computer models which are used to verify the authors’ method of predicting the crack propagation in the Abaqus FEA system.

Determination of Tensile and Compressive Stress Strain Curves from Bend Tests

2004 ◽  
Vol 1-2 ◽  
pp. 133-138 ◽  
Author(s):  
G. Urriolagoitia-Sosa ◽  
J.F. Durodola ◽  
N.A. Fellows
Keyword(s):  
Compressive Stress ◽  
Inverse Method ◽  
Bauschinger Effect ◽  
Stress Strain ◽  
Bending Tests ◽  
Strain Behaviour ◽  
Strain Data ◽  
Tension And Compression ◽  
Bend Tests

A new inverse method has been developed for the simultaneous derivation of tensile and compressive stress strain behaviour from bending tests only. This new procedure can be applied to materials having asymmetric tensile and compressive stress strain behaviour and also materials that have been previously strain hardened (Bauschinger Effect). This paper presents results obtained using the new method and compares them with experimentally obtained tensile and compressive stress strain curves. The agreement of the derived stress strain data in tension and compression is encouraging.

Effects of initial stress state on the subsurface stress distribution after ultrasonic impact treatment on thick specimens

2020 ◽  
pp. 030932472097683
Author(s):  
Chuan Liu ◽  
Jiabin Shen ◽  
Changhua Lin ◽  
Jianfei Wang ◽  
Jianxin Wang
Keyword(s):  
Stress State ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Compressive Stress ◽  
Initial Stress ◽  
Correction Method ◽  
Welding Residual Stress ◽  
Initial Stress State ◽  
Ultrasonic Impact Treatment ◽  
Before And After

Thick welded specimens with different initial stress states were prepared and treated with the ultrasonic impact treatment (UIT). The subsurface stresses before and after UIT were measured by the X-ray diffraction (XRD) method combined with layer removal. The measured results were corrected based on the finite element correction method. The effects of initial high tensile stress and low compressive stress on the in-depth after-UIT stress distributions were investigated. The results show that initial stress has no effects on the stresses induced by the UIT within 1 mm depth and within that depth, UIT can induce almost the same longitudinal and transverse stress curves beneath the surface with a peak compressive stress close to the material yield strength at the depth of near 0.6 mm and 0.8 mm. UIT induces almost the same longitudinal and transverse stresses along with the measured depth under initial low compressive stress state. While under the initial high tensile stress state, the initial stress dominates the final stress distribution over 1 mm depth. Initial high tensile stress (welding residual stress) can reduce the depth of the after-UIT compressive stresses to 62.5% to 75% of that under the initial low-compressive stress state.

scholarly journals Mechanical properties of solid glass bricks

2019 ◽  
Author(s):  
Jiří Fíla ◽  
Martina Eliášová ◽  
Zdeněk Sokol
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Building Materials ◽  
Flat Glass ◽  
Structural Elements ◽  
Compression Tests ◽  
Bending Tests ◽  
Load Bearing ◽  
Three Point Bending ◽  
Solid Glass

Glass as one of the oldest building materials has been used for centuries to fill window openings. In recent years is it increasingly used also for load-bearing structural elements such as beams, columns, ribs, railings, etc. In addition to flat glass and hollow glass blocks, which have been used historically for non-load-bearing partitions and facades, new load bearing structures from solid glass bricks are arising. Their greater use is hampered by a lack of knowledge of their material properties. Also, their joining is difficult, as can be seen from the realized structures and published works focused on the glass bricks masonry. Most often, transparent adhesives or special mortars are used on the joint between glass bricks. In addition to some examples of completed glass brick structures, the paper is aimed at determining the material properties of glass bricks, which are a prerequisite for the design of safe structures. Two sets of experiments were performed. There were made three-point bending tests and compression tests to determine the bending tensile strength, modulus of elasticity and compressive strength of glass bricks.

scholarly journals Mycocomposites: looking for a viable alternative to EPS

2021 ◽  
Author(s):  
Vithoria Réggia Gomes Pessanha ◽  
Maria das Graças Machado Freire ◽  
Michel Picanço Oliveira ◽  
Bárbara Ferreira de Oliveira
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Compression Tests ◽  
Bending Tests ◽  
Three Point Bending ◽  
Synthetic Materials ◽  
Significant Difference ◽  
The Mean ◽  
Compressive Resistance ◽  
Base Substrate

Mycocomposites have received special attention from both academic and commercial environments. These materials give a new purpose to agricultural residues, bringing benefits to companies, society and the environment. Currently, they have been studied to replace synthetic materials such as polyester. However, its field of application is still very limited, making it necessary for more research to be carried out. In this work, mycocomposites were produced in two configurations: without jute and with two jute arranged at 1/3 of the thickness in relation to the surfaces perpendicular to loading plains during bending and compression tests. The base substrate used consisted of coconut mesocarp, white wood sawdust and wheat grain pre-myceliated by the fungus Pycnopurus sanguineus. Analysis by confocal microscopy showed that the fungus produced a network of mycelial hyphae capable of uniting substrate components and incorporated jute. Composites’ mechanical properties were evaluated from three-point bending tests and compression tests. The Shapiro-Wilk tests showed that all determined mechanical properties are normally distributed. The highest compressive resistance (10% deformation) was found in the mycocomposite without jute. The analysis of variance showed that the mean flexural strength of the two configurations analyzed did not present any statistically significant difference; despite this, the composite without jute proved to be more rigid. It was verified that the flexural strength of the produced mycocomposites is located between the values found for the expanded polystyrenes EPS 100 and EPS 150, but that their compressive strength was lower. At first, the materials produced in this work exhibited the necessary properties to be applied in simple pieces such as lampshades, packaging, and plant vases. However, it is still necessary that new studies are carried out to verify the feasibility of its application in the field of engineering, such as in civil construction panels, where EPS are used.

Mechanical Behaviors of High Performance Recycled Aggregate Concrete

2011 ◽  
Vol 80-81 ◽  
pp. 190-194
Author(s):  
Shu Hua Liu ◽  
Zhi Yang Gao ◽  
Li Hua Li
Keyword(s):  
Compressive Stress ◽  
High Performance ◽  
Constitutive Relations ◽  
Strain Curve ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mechanical Behaviors ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Uniaxial Compressive Stress

In this testing research, a series of High Performance Recycled Aggregate Concrete (HPRAC) with recycled aggregate were prepared and their mechanical behaviors were tested, especially uniaxial compressive stress-strain behavior. The influence of the recycled aggregate replacement on mechanical behaviors of HPRAC was studied by changing replacement ratio of recycled aggregate. Testing results show that the strength of HPRAC decrease a little with the increase of the content of recycled aggregate; the uniaxial compressive stress-strain curve of HPRAC is similar to that of ordinary concrete, and the ductibility of HPRAC improve with the increase of the content of recycled aggregate; the fitted regression curves (especially numerical model) approach to measured curves and can be used in constitutive relations analysis for concrete structure.

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