scholarly journals Mechanical Properties of Apple Skin Are Determined by Epidermis and Hypodermis

2014 ◽  
Vol 139 (2) ◽  
pp. 139-147 ◽  
Author(s):  
Bishnu P. Khanal ◽  
Moritz Knoche
Keyword(s):  
Mechanical Properties ◽  
Cold Storage ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Early Event ◽  
Unit Surface Area ◽  
Fruit Skin ◽  
Unit Surface ◽  
Cell Layers ◽  
Apple Cultivars

Mechanical failure of the fruit skin is an early event in the etiology of the disorders russeting and skin spots in a number of apple cultivars including ‘Elstar’ (Malus ×domestica Borkh.). The objective was to quantify the mechanical properties of excised epidermal segments (ES) of fruit skin and of enzymatically isolated cuticular membranes (CM) using uniaxial tensile tests. ES thickness ranged from 0.25 to 1.8 mm because thin ES samples of more uniform thickness are difficult to prepare. Sample values for stiffness (S), maximum force () and strain at () were recorded. Measured values were adjusted by regression to refer to a hypothetical standard ES of 0.5 mm thickness. Generally, S and values were positively related to ES thickness during the preharvest period from 51 to 141 days after full bloom (DAFB) and during the postharvest period from 141 to 259 DAFB in cold storage (1.7 °C, 92% relative humidity). The recorded were independent of ES thickness. The S of a standardized ES decreased slightly from 51 to 90 DAFB, then increased up to 161 DAFB, and then declined. There were essentially no differences in S recorded for isolated CM and ES. The and were highest in young fruit at 51 DAFB but decreased steadily toward harvest and continued to decrease in cold storage after harvest but at a lower rate. The and were markedly lower for CM samples than for ES ones. Monitoring the increased incidence of CM microcracking during a tensile test performed on an ES revealed that CM failure preceded ES failure. The decrease in the for ES during fruit development was accounted for in part by a decrease in the mass of cell wall per unit surface area. Our results show that the epidermal and hypodermal cell layers represent the structural backbone of an apple skin during pre- and postharvest development. Furthermore, CM microcracking has limited relevance to the overall mechanical properties of the skin.

scholarly journals Russeting in Apple Seems Unrelated to the Mechanical Properties of the Cuticle at Maturity

HortScience ◽  
2013 ◽  
Vol 48 (9) ◽  
pp. 1135-1138 ◽  
Author(s):  
Bishnu P. Khanal ◽  
Rejina Shrestha ◽  
Leonie Hückstädt ◽  
Moritz Knoche
Keyword(s):  
Mechanical Properties ◽  
Unit Area ◽  
Tensile Tests ◽  
Maximum Force ◽  
Uniaxial Tensile ◽  
Biaxial Strain ◽  
Subsequent Formation ◽  
Cuticular Membrane ◽  
Fruit Skin ◽  
Commercially Important

Russeting is a commercially important disorder of the fruit skin of apples (Malus ×domestica Borkh.). It is thought to result from microscopic cracking of the cuticle on the fruit surface and the subsequent formation of a periderm just below. The study investigates 22 apples cultivars having widely different russeting susceptibilities to determine if susceptibility could be related to the mechanical characteristics of the cuticles at maturity. The mass per unit area of the cuticular membrane (CM), the dewaxed cuticular membrane (DCM), and the cuticle’s wax content all varied significantly among the cultivars examined but no simple correlative relationships with russeting susceptibility could be found. Across all cultivars, the mass of wax per unit area was linearly related to CM mass per unit area (R = 0.77, P < 0.0001). The cuticle of all cultivars was markedly strained as indexed by the release of biaxial strain in the CM on extraction of the wax. The release of biaxial strain was linearly and positively related to wax mass per unit area. Maximum force () in uniaxial tensile tests, strain at maximum force (), and the stiffness (S) differed widely among the cultivars tested, but, again, there were no relationships between these mechanical properties and russeting susceptibility. Wax extraction from the CM decreased the in uniaxial tensile tests, increased , and decreased the S. Our results show that none of the cuticle variables measured at maturity nor any of the isolated-cuticle mechanical properties contributes significantly to russeting susceptibility.

Comprehensive study on mechanical properties of coated biaxial warp-knitted fabrics

2021 ◽  
pp. 073168442110204
Author(s):  
Bin Yang ◽  
Yingying Shang ◽  
Zeliang Yu ◽  
Minger Wu ◽  
Youji Tao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Least Squares Method ◽  
Tensile Tests ◽  
Tensile Creep ◽  
Base Layer ◽  
Sustained Load ◽  
Uniaxial Tensile ◽  
Membrane Structures ◽  
Knitted Fabrics

In recent years, coated fabrics have become the major material used in membrane structures. Due to the special structure of base layer and mechanical properties, coated biaxial warp-knitted fabrics are increasingly applied in pneumatic structures. In this article, the mechanical properties of coated biaxial warp-knitted fabrics are investigated comprehensively. First, off-axial tensile tests are carried out in seven in-plane directions: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. Based on the stress–strain relationship, tensile strengths are obtained and failure modes are studied. The adaptability of Tsai–Hill criterion is analyzed. Then, the uniaxial tensile creep test is performed under 24-h sustained load and the creep elongation is calculated. Besides, tearing strengths in warp and weft directions are obtained by tearing tests. Finally, the biaxial tensile tests under five different load ratios of 1:1, 2:1, 1:2, 1:0, and 0:1 are carried out, and the elastic constants and Poisson’s ratio are calculated using the least squares method based on linear orthotropic assumption. Moreover, biaxial specimens under four load ratios of 3:1, 1:3, 5:1, and 1:5 are further tensile tested to verify the adaptability of linear orthotropic model. These experimental data offer a deeper and comprehensive understanding of mechanical properties of coated biaxial warp-knitted fabrics and could be conveniently adopted in structural design.

Effect of Polyvinyl Alcohol Concentration on the Mechanical Properties of Collagen/Polyvinyl Alcohol Blends

2015 ◽  
Vol 732 ◽  
pp. 161-164 ◽  
Author(s):  
Jan Vesely ◽  
Lukas Horny ◽  
Hynek Chlup ◽  
Milos Beran ◽  
Milan Krajicek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Stress ◽  
Polyvinyl Alcohol ◽  
Modulus Of Elasticity ◽  
Tensile Tests ◽  
Ultimate Tensile Stress ◽  
Alcohol Concentration ◽  
Uniaxial Tensile ◽  
Initial Modulus ◽  
Water Saturated

The effects of the polyvinyl alcohol (PVA) concentration on mechanical properties of hydrogels based on blends of native or denatured collagen / PVA were examined. Blends of PVA with collagen were obtained by mixing the solutions in different ratios, using glycerol as a plasticizer. The solutions were cast on polystyrene plates and the solvent was allowed to evaporate at room temperature. Uniaxial tensile tests were performed in order to obtain the initial modulus of elasticity (up to deformation 0.1), the ultimate tensile stress and the deformation at failure of the material in the water-saturated hydrogel form. It was found that the material was elastic and the addition of PVA helped to enhance both the ultimate tensile stress and modulus of elasticity of the films. Samples prepared from denaturated collagen showed the higher ultimate tensile stress and the deformation at failure in comparison with those prepared from native collagen. The results suggest that we could expect successful application of the collagen/PVA biomaterial for tissue engineering.

Mechanical properties of PVDF-coated fabric under tensile tests

2015 ◽  
Vol 35 (4) ◽  
pp. 377-390 ◽  
Author(s):  
Andrzej Ambroziak
Keyword(s):  
Mechanical Properties ◽  
Polyvinylidene Fluoride ◽  
Cyclic Load ◽  
Tensile Tests ◽  
Woven Fabrics ◽  
Uniaxial Tensile ◽  
Cyclic Tests ◽  
Comprehensive Investigation ◽  
Coated Fabric ◽  
Coated Fabrics

Abstract This article describes the laboratory tests necessary to identify the mechanical properties of the polyvinylidene fluoride (PVDF)-coated fabrics named Precontraint 1202S and Precontraint 1302S. First, a short survey of the literature concerning the description of coated woven fabrics is presented. Second, the material parameters for PVDF-coated fabrics are specified on the basis of biaxial tensile tests. A comparison of the 1:1 biaxial and the uniaxial tensile tests results is also given. Additionally, biaxial cyclic tests were performed to observe the change of immediate mechanical properties under cyclic load. The article is aimed as an introduction to a comprehensive investigation of the mechanical properties of coated fabrics.

Correlation among Microstructure, Texture, and Properties along the Thickness Direction in As-Hot-Rolled and As-Solution-Quenched Al7055 Thick Plates

2021 ◽  
Vol 1026 ◽  
pp. 65-73
Author(s):  
Kai Zhu ◽  
Hong Wei Yan
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Tensile Tests ◽  
Rolled Plate ◽  
Uniaxial Tensile ◽  
Thickness Direction ◽  
Electron Backscattered Diffraction ◽  
Thick Plates ◽  
Aluminum Plates ◽  
Hot Rolled

Both microstructure inhomogeneity and mechanical property diversity along the thickness direction in rolled thick aluminum plates have been considered to have a remarkable impact on the performance and properties of the products made from the plates. In this study, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) characterizations of microstructure and texture types along the thickness directions of Al7055 thick plate specimens prepared using two conditions, hot-rolling and solution-quenching, were performed. To examine the mechanical properties, uniaxial tensile tests were also carried out on specimens machined from both types of thick plates, using a layered strategy along the thickness direction. The results indicate that both the microstructure and mechanical properties are inhomogeneous under the two conditions. Furthermore, it is evident that there is a hereditary relationship between the mechanical properties of the two plates—areas with higher yield strength in the as-hot-rolled plate correspond to areas with the higher yield strength in the as-solution-quenched plate

The tensile behaviour of biaxial and triaxial braided fabrics

2016 ◽  
Vol 47 (8) ◽  
pp. 2184-2204 ◽  
Author(s):  
Duchamp Boris ◽  
Legrand Xavier ◽  
Soulat Damien
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Mechanical Behaviour ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Tensile Behaviour ◽  
Linear Mass ◽  
Double Peak ◽  
Specific Behaviour ◽  
Braiding Angle

The tensile behaviour of braid reinforcement is classically described by the behaviour of composite elaborated from these reinforcements. Few studies concern the tensile behaviour of braided fabrics. In this paper biaxial and triaxial braids are manufactured on a braiding loom. The evolution of key parameters as linear mass and braiding angle in function of process parameters is presented. Braid reinforcements are characterized in uniaxial tensile. The mechanical behaviour is analysed and compared in function of the braiding angle, but also different kinds of braid are considered. A specific behaviour called “double-peak” is identified for triaxial braids which have a higher braiding angle. The evolution of the braiding angle measured during tensile tests gives a comprehension on the mechanical behaviour of dry braids. Associated with this experimental study, an analytical model is also proposed, to predict mechanical properties of braid reinforcements.

Cellulose Whiskers Micro-Fibers Effect in the Mechanical Proprieties of PP and PLA Composites Fibers Obtained by Spinning Process

2011 ◽  
Vol 146 ◽  
pp. 12-26 ◽  
Author(s):  
A. Gherissi ◽  
R.Ben Cheikh ◽  
E. Dévaux ◽  
Fethi Abbassi
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Failure Resistance ◽  
Cellulose Whiskers ◽  
Limit Strength

In this study, we present the manufacturing process of two new composites materials in the form of long fibers of polylactic-acid (PLA) or polypropylene (PP), reinforced by cellulose whiskers micro-fibers loads. In order to evaluate the mechanical properties of these advanced materials, a several uniaxial tensile tests were carried out. The PP and the PLA have initially been spinning without the addition of cellulose whiskers micro-fibers. In order to study the effects of cellulose whiskers micro-fibers reinforcements in the Mechanical behavior of the PLA and PP filaments, we determinate the proprieties of these advanced material from the tensile results. For the PP composite filaments material case, the whiskers reinforcement increases Young's modulus and failure resistance, but it reduces the limit strength failure. For the PLA composites the addition of 1% wt of cellulose whiskers from the total volume fraction of the material, increase the Young’s modulus more than 50% and a decrease of the failure resistance and the limit strength of composite. The obtained composites fibers are very rigid and brittle. What follows, that the addition of cellulose whiskers micro fibers in PP matrix, provides mechanical properties more convenient compared to the PLA matrix.

Tensile properties of the FFF-processed thermoplastic polyurethane (TPU) elastomer

2021 ◽  
Author(s):  
Budi Arifvianto ◽  
Teguh Nur Iman ◽  
Benidiktus Tulung Prayoga ◽  
Rini Dharmastiti ◽  
Urip Agus Salim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Low Cost ◽  
Thermoplastic Polyurethane ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Fused Filament Fabrication ◽  
Raster Angle ◽  
Manufacturing Techniques

Abstract Fused filament fabrication (FFF) has become one of the most popular, practical, and low-cost additive manufacturing techniques for fabricating geometrically-complex thermoplastic polyurethane (TPU) elastomer. However, there are still some uncertainties concerning the relationship between several operating parameters applied in this technique and the mechanical properties of the processed material. In this research, the influences of extruder temperature and raster orientation on the mechanical properties of the FFF-processed TPU elastomer were studied. A series of uniaxial tensile tests was carried out to determine tensile strength, strain, and elastic modulus of TPU elastomer that had been printed with various extruder temperatures, i.e., 190–230 °C, and raster angles, i.e., 0–90°. Thermal and chemical characterizations were also conducted to support the analysis in this research. The results obviously showed the ductile and elastic characteristics of the FFF-processed TPU, with specific tensile strength and strain that could reach up to 39 MPa and 600%, respectively. The failure mechanisms operating on the FFF-processed TPU and the result of stress analysis by using the developed Mohr’s circle are also discussed in this paper. In conclusion, the extrusion temperature of 200 °C and raster angle of 0° could be preferred to be applied in the FFF process to achieve high strength and ductile TPU elastomer.

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