scholarly journals STUDY ON TENSILE MECHANICAL PROPERTY AND MICROSTRUCTURE OF FRUIT AND VEGETABLE PEELS

2019 ◽  
Vol 59 (3) ◽  
pp. 227-236 ◽  
Author(s):  
Juxia Wang ◽  
Decong Zheng ◽  
Qingliang Cui ◽  
Shuanghua Xu ◽  
Bingyao Jiang
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Fruits And Vegetables ◽  
Fracture Strain ◽  
Testing Machine ◽  
Strain Curve ◽  
Mechanical Equipment ◽  
Fruit And Vegetable ◽  
Stress Strain ◽  
Mean Values

Fruit and vegetable peels exert a protective effect on fruits as constituent parts of the outermost tissue and their properties are of great importance to reducing fruit and vegetable mechanical injury. Four kinds of fruit and vegetable peels such as Nagafu apple, Crisp pear, Tainong mango and long eggplant were chosen to perform longitudinal and transverse tests of tensile property by means of electronic universal testing machine. Stress-strain curve, tensile strength, elastic modulus and fracture strain of peels were obtained; and the microstructures of four kinds of peels were scanned using an electron microscope (SEM). The results indicated that cubic polynomials proved superior for quantifying the stress-strain non-linear relationship of peels and the fitting error of tensile strength is less than 10 parts per thousand. Tensile strength, elastic modulus and fracture strain of peels were different in the case of different fruits and vegetables cultivated and different parts of the same peel; fruit and vegetable peels belong to anisotropic heterogeneous materials and have certain strength. The mean values of tensile strength and fracture strain of the long eggplant peel are the biggest in four kinds of peels and that of elastic modulus of Nagafu apple peel is the largest; long eggplant and Nagafu apple peels had better resistance to damage sensibility than Crisp pear peel. The bearing capacity of the peels depends on the number, width and distribution of microcracks on the surface, and the shape of the epidermal cells and fruit dot on peels; the number of microcracks is bigger and the width of microcracks is wider, the tensile strength is smaller and the elastic modulus of peel is bigger with the slippage increase of epidermis cells. This study provides basic technical parameters for mechanical equipment design for fruit and vegetable during harvesting, processing, packaging, storing and transporting and builds the correlations between macro-mechanics properties and microstructures of fruit and vegetable peels.

The Stress-Strain Relationship in Ebonite

1934 ◽  
Vol 7 (1) ◽  
pp. 197-211
Author(s):  
B. L. Davies
Keyword(s):  
Tensile Strength ◽  
Plastic Flow ◽  
Testing Machine ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Tensile Testing Machine ◽  
Hooke’S Law ◽  
Hooke's Law ◽  
Soft Rubber

Abstract 1. A simple “extensometer” has been devised for the more accurate measurement of small elongations in hard rubber samples, thus enabling stress-strain curves to be obtained on a standard tensile testing machine. 2. The form of the curve has been described more fully than heretofore. It shows that hard rubber does not deform exactly in accordance with Hooke's Law, but exhibits plastic flow. 3. Deviations from Hooke's Law shown by the experimental curves depend upon the speed of stretching. Increased speed of elongation has been found to give higher readings of tensile strength. 4. Prolonged mastication of the rubber gives a weaker product, similar effects being obtainable by the use of a neutral softener. 5. The effects of increasing time of vulcanization have been described. The range of curves showing transition from over-cured soft rubber to ebonite indicates that the hard rubber curve is possibly related to the initial portion of the soft rubber curve. The plasticity of the overvulcanized rubber, as indicated by the deviation from Hooke's Law, increased with time of vulcanization until the “semi-ebonite” stage was reached. 6. The leather-like “semi-ebonites” differed from soft and hard rubber inasmuch as they were extremely sensitive to small changes in time of vulcanization, and inasmuch as their plasticity was such that the velocity of plastic flow was comparable with the rate of pulling (1 in. per minute), at a particular point in the test they experienced a large elongation at constant load, i. e., the velocity of flow was equal to the speed of pulling. Their plasticity decreased with further vulcanization. 7. The longest cures in the above-mentioned group gave products which were rigid at room temperature. Since these must be more resistant to shock than vulcanizates in a higher state of cure, it seems that the best technical cure of ebonite for mechanical purposes is that which gives maximum tensile strength combined with the property of undergoing considerable plastic flow (of the order of 5 per cent) at the constant maximum load, and at an arbitrarily fixed rate of stretching, the temperature being commensurate with the thermal conditions of service. Such a cure is clearly indicated by the stress-strain curve. 8. Accelerated ebonite mixings are more sensitive to time of cure than rubber-sulfur stocks without accelerators. An accelerator may produce very little effect on the tensile strength and breaking elongation, but may yield a stock which “scorches” readily. This prevulcanization was detrimental to the mechanical properties of the vulcanizate, even though it was so slight that its presence was not detected during normal processing. 9. Mineral rubber in ebonite stocks has been shown to accelerate the cure as indicated by the stress-strain curve. 10. Stocks containing high loadings of gas black gave vulcanizates which were weak and brittle. The effect of the black on the stiffness was similar to that produced by further cure. 11. The stress-strain curve provides a reliable means whereby stocks containing different accelerators and other compounding ingredients may be compared at equivalent states of vulcanization.

Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1

1970 ◽  
Vol 185 (1) ◽  
pp. 1149-1158 ◽  
Author(s):  
K. Bitans ◽  
P. W. Whitton
Keyword(s):  
Shear Strain ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Strain Rates ◽  
Adiabatic Shear Bands ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
The Given ◽  
Tubular Specimens

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.

Effects of AP and AP-ethyl on the properties of PA6

2017 ◽  
Vol 31 (12) ◽  
pp. 1609-1618
Author(s):  
Long Lijuan ◽  
He Wentao ◽  
Li Juan ◽  
Xiang Yushu ◽  
Qin Shuhao ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fracture Surface ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Cone Calorimeter Test ◽  
Mean Size ◽  
The Mean

In this work, the effects of inorganic phosphinate flame retardant of aluminum hypophosphite (AP) and organic phosphinate flame retardant of ethyl substituted phosphinates (AP-ethyl) on the thermal degradation, flame performance, and mechanical properties of polyamide 6 (PA6) were investigated. Scanning electron micrograph showed AP with the shape of bulk and the mean size of 8 μm while AP-ethyl with irregular shape and the mean size of 30 μm. Thermal analysis indicated that the thermal degradation behavior of flame-retardant PA6 was different from pure PA6. Moreover, the cone calorimeter test results revealed that peak heat release rate (PHRR) of PA6/AP (85/15) and PA6/AP-ethyl (85/15) decreased by 51% and 64%, respectively, compared with pure PA6. Furthermore, pure PA6 showed ductile stress–strain curve with the tensile strength of 54.8 MPa. However, PA6/AP and PA6/AP-ethyl displayed brittle stress–strain curve and their tensile strength decreased to 52.3 and 47.1 MPa, respectively. In addition, pure PA6 showed a glossy and tough fracture surface morphology. The rough fracture surface morphologies for PA6/AP and PA6/AP-ethyl were observed, and the interface of PA6/AP was more obscure than that of PA6/AP-ethyl. Consequently, the small particle size of AP had a more uniform dispersion in PA6 matrix.

Study on the Performances and Interfacial Structure of Magnesium Hydroxide Whiskers/ABS Composites

2011 ◽  
Vol 109 ◽  
pp. 46-50
Author(s):  
Yu Zhi Jiang ◽  
Li Li Zhang ◽  
Yan Bo Li
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Magnesium Hydroxide ◽  
Testing Machine ◽  
Surface Modifications ◽  
Interfacial Structure ◽  
Melt Extrusion ◽  
Elongation At Break ◽  
Universal Testing ◽  
Mechanical Performances

The magnesium hydroxide (MH) whiskers / ABS composites were prepared by melt-extrusion with modified whiskers as filler. The mechanical performances, including the tensile strength, elongation at break and elastic modulus, were tested by electronic universal testing machine. The results showed that with the increasing of the whisker dosage, the tensile strength and elongation at break reduced gradually, and the elastic modulus get maximum when it is 25%.The morphology on fracture of composites was analyzed by SEM. The conclusions are the whiskers of surface modifications can be evenly distributed in the composites and bond partly with ABS. that it is necessary to enhance the combine strength of interface on excellence performances of composites.

Experimental Research on Mechanical Properties of Recycled Aggregate Concrete under Uniaxial Loading

2013 ◽  
Vol 671-674 ◽  
pp. 1736-1740
Author(s):  
Xue Yong Zhao ◽  
Mei Ling Duan
Keyword(s):  
Elastic Modulus ◽  
Coarse Aggregate ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Peak Strain ◽  
Stress Strain ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate

The complete stress-strain curves of recycled aggregate concrete with different recycled coarse aggregate replacement percentages were tested and investigated. An analysis was made of the influence of varying recycled coarse aggregate contents on the complete stress-strain curve, peak stress, peak strain and elastic modulus etc. The elastic modulus of RC is lower than natural concrete (NC), and with the recycled coarse aggregate contents increase, it reduces. While with the increase of water-cement ratio (W/C), recycled concrete compressive strength and elastic modulus improve significantly. In addition, put forward a new equation on the relationship between Ec and fcu of the RC.

Comparison between traditional and alternative biocompatible welding techniques used in orthodontic devices

2020 ◽  
pp. 146531252097240
Author(s):  
Fernanda de Souza Henkin ◽  
Luciane Macedo de Menezes ◽  
Berenice Anina Dedavid ◽  
Cátia Abdo Quintão
Keyword(s):  
Tensile Strength ◽  
Laser Welding ◽  
Mechanical Performance ◽  
Steel Wire ◽  
Testing Machine ◽  
Mean Values ◽  
Welding Spot ◽  
Microstructural Morphology ◽  
Orthodontic Devices

Objective: To compare the mechanical strength of joints made by conventional soldering with those made by alternative, more biocompatible, methods (spot, tungsten inert gas [TIG] and laser welding), and to compare the microstructural morphology of wires welded with these techniques. Design: In vitro, laboratory study. Methods: Forty stainless-steel wire segments with 0.8-mm diameter were joined by silver soldering, spot, laser and TIG welding. Ten specimens were produced for each one. Tensile strength test was performed 24 h after welding on the Emic DL2000™ universal testing machine, using a load cell of 1000 N with a crosshead speed of 10 mm/min. Results: The highest tensile strength mean values were obtained with silver soldering (532 N), next were laser (420 N), spot (301 N) and TIG (296 N) welding. Statistically significant differences were observed between the groups; the Dunn post-hoc test revealed differences between laser and spot welding ( p=0.046), laser and TIG ( p = 0.016), spot and silver ( p <0.001), and silver and TIG ( p <0.001). Conclusion: Laser welding strength is high, and comparable to silver welding. Spot and TIG techniques present comparable and significantly lower strengths. The four methods presented resistance values compatible with orthodontic use. The microstructural morphology is different for each technique. The association between the mechanical performance and the microstructure evaluation shows that laser presented the highest quality joint.

The Development of a Machine for High-Speed Testing of Materials

1937 ◽  
Vol 135 (1) ◽  
pp. 467-483
Author(s):  
R. J. Lean ◽  
H. Quinney
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
High Speed ◽  
Testing Machine ◽  
Strain Curve ◽  
Maximum Point ◽  
Variable Speed ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
High Speed Machine

The paper contains an account of a research into the effect on metals of different speeds of fracture, using a specially designed high-speed testing machine which is described in detail. The experiments were conducted both in this machine and in a 5-ton variable-speed autographic tensile machine, on five steels, the rate of loading being varied for each. With the high-speed machine toughness, ductility, time to produce fracture, and the stress-strain curve were obtained. The results of these combined tests, given in tables and graphs, show that there is a marked increase in stress due to higher speed of testing; and also that the work required to cause fracture increases with the speed. For mild steel the stress at the initial yield point was found to be in excess of that at the maximum point, when the speed of testing was increased the ductility did not appear to suffer.

Stress-Strain Behavior of an Aluminum Alloy Under Transient Strain-Rates

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Y. W. Kwon ◽  
Y. Esmaeili ◽  
C. M. Park
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Fracture Strain ◽  
Strain Curve ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Single Strain ◽  
Transient Strain ◽  
Strain Rate Loading

Because most structures are subjected to transient strain-rate loading, an experimental study was conducted to investigate the stress-strain behaviors of an aluminum alloy undergoing varying strain-rate loading. To this end, uniaxial tensile loading was applied to coupons of dog-bone shape such that each coupon underwent two or three different strain-rates, i.e., one rate after another. As a basis, a series of single-strain-rate tests was also conducted with strain-rates of 0.1–10.0 s−1. When the material experienced multistrain-rate loading, the stress-strain curves were significantly different from any single-strain-rate stress-strain curve. The strain-rate history affected the stress-strain curves under multistrain-rate loading. As a result, some simple averaging of single-strain-rate curves did not predict the actual multistrain-rate stress-strain curve properly. Furthermore, the fracture strain under multistrain-rate loading was significantly different from that under any single-strain-rate case. Depending on the applied strain-rates and their sequences, the former was much greater or less than the latter. A technique was proposed based on the residual plastic strain and plastic energy density in order to predict the fracture strain under multistrain-rate loading. The predicted fracture strains generally agreed well with the experimental data. Another observation that was made was that the unloading stress-strain curve was not affected by the previous strain-rate history.

Dynamic Tensile Characteristics of Nuclear-Grade Graphite IG-11

2014 ◽  
Vol 566 ◽  
pp. 61-66
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
Tensile Stress ◽  
Strain Rate ◽  
Fracture Strain ◽  
Testing Machine ◽  
Nuclear Grade ◽  
Dynamic Tests ◽  
Stress Strain ◽  
Fine Grained ◽  
Split Hopkinson ◽  
Static And Dynamic Tests

The effect of strain rate up to nearly = 102/s on the tensile stress-strain properties of isotropic fine-grained nuclear-grade graphite IG-11 was investigated. Cylindrical tensile specimens machined out of graphite bars were used in both static and dynamic tests. The dynamic tensile stress-strain curves up to fracture were determined using the split Hopkinson bar (SHB). The low and intermediate strain-rate tensile stress-strain relations up to fracture were measured on an Instron 5500R testing machine. It was demonstrated that the ultimate tensile strength increases slightly, while the fracture strain and absorbed energy up to fracture decrease dramatically with increasing strain rate. Macro and microscopic examinations revealed a slight difference in the fracture surfaces between the static and dynamic tension specimens.

scholarly journals Repair Adhesive Strength of Conventional and Bulk Fill Resins Using Different Bonding Techniques

2021 ◽  
Vol 22 (3) ◽  
pp. 185-190
Author(s):  
Wilian Segatto Zanelli ◽  
Mariana Dias Flor-Ribeiro ◽  
Rodrigo Barros Esteves ◽  
Luís Roberto Marcondes Martins ◽  
Flávio Henrique Baggio Aguiar ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
Adhesive System ◽  
Composite Resins ◽  
The Other ◽  
Adhesive Systems ◽  
Mean Values ◽  
Normality Test ◽  
Point Test

AbstractThis research aimed to evaluate the bond strength by micro tensile strength (µTBS), elastic modulus (EM) and flexural strength (FS) by the three-point test using three types of composite resins: Charisma Diamond, Filtek Z350 and Tetric N-Ceram Bulk Fill; and three adhesion techniques: adhesive, silane, silane and adhesive. The combinations of each resin with the adhesive technique resulted in nine groups (n = 12). Initially, with the composites, EM and FS tests were performed. Sequentially, each fragment was repaired with the different adhesive systems. All samples were subjected to µTBS testing on a universal assay machine. Data were subjected to the normality test and the parametric ANOVA test. Charisma resin showed the highest values in EM and RF compared to the other composite resins (p <0.05). The highest µTBS value was for silane + adhesive repaired Charisma resin. The lowest µTBS values were in Bulk Fill resin, regardless of adhesive system. The EM and FS results showed that Filtek Z350 resins had the best results, while bulk fill resins had lower results. It was concluded that Charisma and Filtek Z350 resins presented better results. However, in the bulk fill group, the lowest mean values of µTBS, FS and EM were obtained, as well as the lowest value in EM.Keywords: Composite Resins. Adhesives. Flexural Strength.ResumoEsta pesquisa teve como objetivo avaliar a resistência de união (RU) por resistência à microtração, módulo de elasticidade (ME) e resistência à flexão (RF) pelo teste de três pontos, utilizando três tipos de resinas compostas: Charisma Diamond, Filtek Z350 e Tetric N-Ceram Bulk Fill; e três técnicas de adesão: adesivo, silano, silano e adesivo. As combinações de cada resina com a técnica adesiva resultaram nove grupos (n= 12). Inicialmente, com os compósitos foram realizados testes de ME e RF. Sequencialmente, cada fragmento foi reparado com os diferentes sistemas adesivos. Todas as amostras foram submetidas ao teste de RU por microtração em uma máquina de ensaio universal. Os dados foram submetidos ao teste de normalidade e ao teste paramétrico ANOVA. A resina Charisma apresentou os maiores valores no ME e RF em relação às demais resinas compostas (p <0,05). O maior valor de RU foi para a resina Charisma reparada com silano + adesivo. Os menores valores de RU foram na resina Bulk Fill, independentemente do sistema adesivo. Os resultados no ME e RF mostraram que as resinas Filtek Z350 obtiveram os melhores resultados, enquanto as resinas bulk fill obtiveram resultados inferiores. Conclui-se que as resinas Charisma e Filtek Z350 apresentaram melhores resultados. Entretanto, no grupo de bulk fill obteve se as menores médias de RU, RF e ME, bem como o menor valor no ME.Palavras-chave: Resinas Compostas. Adesivos. Resistência à Flexão.

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