Effect Of Mechanical Damage Research Articles

Constitutive and insect-induced transcriptomes of weevil-resistant and susceptible Sitka spruce.

Spruce weevil (Pissodes strobi) is a significant pest of regenerating spruce (Picea) and pine (Pinus) forests in North America. Weevil larvae feed in the bark, phloem, cambium, and outer xylem of apical shoots, causing stunted growth or mortality of young trees. We identified and characterized constitutive and weevil-induced patterns of Sitka spruce (Picea sitchensis) transcriptomes in weevil-resistant (R) and susceptible (S) trees using RNA sequencing (RNA-seq) and differential expression (DE) analyses. We developed a statistical model for the analysis of RNA-seq data from treatment experiments with a 2×3 factorial design to differentiate insect-induced responses from the effects of mechanical damage. Across the different comparisons, we identified two major transcriptome contrasts: A large set of genes that was constitutively DE between R and S trees, and another set of genes that was DE in weevil-induced S-trees. The constitutive transcriptome unique to R trees appeared to be attuned to defense, while the constitutive transcriptome unique to S trees was enriched for growth-related transcripts. Notably, a set of transcripts annotated as "fungal" was detected consistently in the transcriptomes. Fungal transcripts were identified as DE in the comparison of R and S trees and in the weevil-affected DE transcriptome of S trees, suggesting a potential microbiome role in this conifer-insect interaction.

Effects of Mechanical Damage of Fruit Falling on Passion Fruit Quality and Postharvest Physiological Responses

Effects of Mechanical Damage of Fruit Falling on Passion Fruit Quality and Postharvest Physiological Responses

Micro-structural Damage to Coal Induced by Liquid CO2 Phase Change Fracturing

The technology of liquid carbon dioxide phase change fracturing (LCPCF) was used to enhance the permeability of coal seams. The combination of mechanical tests, scanning electron microscopy (SEM) and high-pressure mercury intrusion porosimetry was adopted to study the damage characteristics of coal micro-structures. LCPCF had mechanical damage effects on coal micro-structures to varying degrees, and the maximum reduction in compressive strength reached approximately 25%. SEM results confirmed that surface morphology of coal was remarkably altered after conducting LCPCF. The fractal dimension (D) of coal subjected to LCPCF ranged from 1.5186 to 1.8794, demonstrating the three-stage changing trends. HP-MIP results showed that LCPCF mainly affected pores of > 100 nm within coal, and pores 1.5 m, the obvious reduction in macro-pore and micro-fracture volumes implied that the fracturing effect was attenuated with the increase in distance. Once distance was > 6.0 m, pore and fracture structures within coal tended to be stable. Thus, in this study, the influence scope of LCPCF was around 6.0 m for a single fracturing borehole.

Fatigue crack growth mechanisms in powder metallurgy Ni-based superalloys—A review

Powder metallurgy (PM) Ni-based superalloys are widely used for aeroengine turbine disc applications due to their excellent mechanical properties and good corrosion resistance at elevated temperatures. Understanding the fatigue crack growth (FCG) mechanisms of PM Ni-based superalloys is important for both disc alloy development and life prediction of disc components in these advanced aeroengines where damage tolerance design prevails. FCG in PM Ni-based superalloys is a complicated function of microstructure, temperature, loading conditions and environment and is usually a consequence of the synergistic effects of fatigue, creep and environmental damage. In this review, the mechanisms controlled by microstructural features including grain size, grain misorientation, γ′ size and distribution on short and long FCG behaviour in PM Ni-based superalloys are discussed. The contribution of creep and environmental damage to FCG has been critically assessed. The competing effects of mechanical damage (i.e. fatigue and creep) and environmental damage at the crack tip are microstructure-sensitive, and usually results in transition between transgranular, mixed-trans-intergranular and intergranular FCG depending on the contribution of environmental damage to FCG processes.

Effect of moisture and freeze-thaw damage on microwave healing of asphalt mixes

Microwave heating/healing is a kind of maintenance technique to repair micro-cracks in asphalt mixes. This method was conducted mostly on unaged materials, and the effects of moisture and freeze-thaw damages have not completely been studied. The fluidity of the asphalt binder, accomplished by heating, increases the ability of binder to fill micro-cracks and heal the asphalt mixes. Moisture and freeze-thaw damage increase the modulus of asphalt binder resulting decrease of fluidity of material. In contrast, moisture and freeze-thaw damages could reduce the ability of mixes to heal. In this research, mixes were prepared using neat and activated carbon modified asphalt binders. In order to assess the microwave heating properties, mixes were subjected to different levels of moisture and freeze-thaw conditions. The microwave heating performance was investigated under electromagnetic radiation. It was found that activated carbon is a proper binder-based additive that increases electromagnetic absorption of asphalt mixes. Indirect Tensile (IDT) and Semi-Circular Bending (SCB) specimens were fabricated, and different levels of moisture and freeze-thaw cycles were applied. For quantification of microwave healing capability of damaged asphalt concrete mixes, the cyclic fracture-healing tests were conducted on IDT and SCB specimens. Individual and combined effects of mechanical damage, fracture temperature, notch length, moisture, and freeze-thaw cycles on microwave healing performance of asphalt concrete mixes were investigated. Results showed that moisture and freeze-thaw damages have adverse effects on microwave healing performance of asphalt concrete mixes. Increased critical factors caused further detrimental effects on microwave healing performance of mixes.

Comparison of rock outcrop permeability with increasing distance from the Rokko fault zone

Fault zones, which have relatively high permeability compared to country rock, can act as hydraulic conduits between subsurface and deep groundwaters, and their outcrop areas can be recharge or discharge areas for deep groundwater systems. Therefore, the characterization of fault zone permeability is essential to investigate deep groundwater systems, which are necessary for the assessment of geological waste disposal. Fault zone media is not merely damaged by fault activity but is altered by the other processes, such as weathering and hydrothermal alteration, whose influences vary with the distance from the fault core and the depth from the ground surface. Consequently, the permeability of fault zone media varies by location even within a fault zone. However, the quantitative evaluation of the fault zone permeability has been rarely attempted because it not only requires surface surveys and experiments but also information on both hydrothermal-alteration and weathering processes. Herein, we present a quantitative investigation of the effects of weathering and hydrothermal alteration on the outcrop permeability of the Rokko active fault zone with Arima hot spring upwelling in southwestern Japan. The changes in the permeabilities of granite outcrops around the Rokko active fault zone were captured by on-site and laboratory experiments. The results show that the outcrop permeability increases on approaching the fault zone; however, this increase cannot be characterized by a conventional empirical model describing the effects of mechanical damage on permeability near the fault zone. Mineralogical analyses and inspections of outcrops and rock samples reveal that minerals altered or formed by hydrothermal alteration and/or weathering change the connectivity of conductive fractures attributed to mechanical damage and thus, affect outcrop permeabilities in this area. This suggests that the permeability variation in surface granite subjected to both fault activity and weathering can be indexed by determining the alteration mineral assemblage, which serves as information on the areal, hydraulic influences on the fault zone.

机械损伤对茶用杜仲光合作用以及酚类物质影响的研究

机械损伤对茶用杜仲光合作用以及酚类物质影响的研究

Resistance of Geosynthetics against the Isolated and Combined Effect of Mechanical Damage under Repeated Loading and Abrasion.

The behaviour of materials used for developing engineering structures should be properly foreseen during the design phase. Regarding geosynthetics, which are construction materials used in a wide range of engineering structures, the installation on site and the action of many degradation agents during service life may promote changes in their properties, endangering the structures in which they are applied. The evaluation of the damage suffered by geosynthetics, like installation damage or abrasion, is often carried out through laboratory tests. This work studied the behaviour of five geosynthetics (three geotextiles and two geogrids) after being individually and successively exposed to two degradation tests: mechanical damage under repeated loading and abrasion. The short-term mechanical and hydraulic behaviours of the geosynthetics were analysed by performing tensile tests and water permeability normal to the plane tests. Reduction factors were determined based on the changes occurred in the tensile strength of the geosynthetics. Findings showed that mechanical damage under repeated loading and abrasion tended to affect the mechanical and hydraulic properties of the geosynthetics and that the reduction factors calculated according to the traditional method may not be able to represent accurately the damage suffered by the materials when exposed successively to the degradation mechanisms.

Effect of Mechanical Damage on the Thermal Conductivity of Granite

In this work, the effect of mechanical damage on the thermal conductivity of granite was experimentally investigated. Granite samples were artificially damaged through cyclic loading and unloading tests, with the strain evolution and acoustic emission activity monitored simultaneously. P-Wave velocity of the damaged samples was tested to evaluate the damage effect. Thermal conductivity of the undamaged and damaged granite samples was tested using optical scanning method. The influence of mechanical damage on thermal conductivity was analyzed. Thermal conductivity difference in different testing directions was analyzed based on the experiment results in six scanning lines on the two surfaces of each disk sample. The results indicate that thermal conductivity of damaged samples reduced compared with that of the undamaged samples, while the thermal inhomogeneity factor increased. Thermal conductivity increased in water-saturated condition for both undamaged and damaged samples. The increased rate of damaged samples was bigger than that of the undamaged samples. The mechanical damage treatment caused the increase in the thermal conductivity difference in different testing directions. The difference decreased when samples were water saturated. Research results in this work can provide better knowledge to the evolution mechanism of thermal conductivity of engineering rock masses.

Effects of Mechanical Damage and Temperature on the Electrical Performance of CIGS Thin-Film Solar Cells

In this paper, we investigate the effect of mechanical damage and temperature on copper indium gallium diselenide (CIGS) thin-film solar cells through experiments and modeling. After generating mechanical damage on CIGS solar cell with 20% increments, the electrical performance was measured (current–voltage curve) while temperature was varying from 10 to 70 °C at 20° increments. Other measured values are open-circuit voltage ( V oc), fill factor (ff), maximum power ( P max). Those electrical values ( V oc, ff, P max) are found as a function of temperature and percent damage. Moreover, the parameters of the single diode solar cell model were obtained as a function of temperature and percentage damage: light generation current ( IL ), saturation current ( I0 ), shunt resistance ( R sh), and series resistance ( R s ). Our paper contributes to the deeper understanding of the concurrent effect of temperature and mechanical damage to solar cells.

Sweet lemon mechanical damage detection using image processing technique and UV radiation

Non-destructive measurement of qualitative parameters of agricultural produce is quite beneficial in the postharvest operations. The consequential effect of mechanical damage in citrus fruits is rarely visible in their appearance compared to other commodities. The purpose of this study was to propose a fast, non-destructive method for sweet lemon mechanical damage detection using image processing technique and UV radiation. For this purpose, 135 sweet lemons were tested based on a completely randomized factorial design. In order to examine mechanical damage, the independent variables included drop height, fruit diameter and tempering period (holding time at room temperature after treatment). Fruits were dropped from heights of 2, 2.5 and 3 m onto the ground. Then images were captured under UV light having a wavelength of 365 nm, 1, 3 and 6 days after treatment. The images were sent to a PC and analyzed using MATLAB software. “Green Spot Index” or GSI was defined to show the extent of mechanical damage. Results of the analysis of variance showed that the percentage of green spots on fruit skin is significant at the 1% level considering the main and double interaction effects of drop height and fruit diameter. Green spot index significantly increases with the level of mechanical damage. Accuracy of the developed method in differentiating the bruised and undamaged fruits was found to be 100%.

Effect of mechanical damage and wound healing on the viscoelastic properties of stems of flax cultivars (Linum usitatissimum L. cv. Eden and cv. Drakkar).

As plant fibres are increasingly used in technical textiles and their composites, underlying principles of wound healing in living plant fibres are relevant to product quality, and provide inspiration for biomimetic healing in synthetic materials. In this work, two Linum usitatissimum cultivars differing in their stem mechanical properties, cv. Eden (stems resistant to lodging) and cv. Drakkar (with more flexible stems), were grown without wound or with stems previously wounded with a cut parallel or transversal to the stem. To investigate wound healing efficiency, growth traits, stem biomechanics with Dynamic Mechanical Analysis and anatomy were analysed after 25-day recovery.Longitudinal incisions formed open wounds while transversal incisions generated stem growth restoring the whole cross-section but not the original stem organisation. In the case of transversal wound healing, all the bast fibre bundles in the perturbed area became lignified and pulled apart by parenchyma cells growth. Both Linum cultivars showed a healing efficiency from 79% to 95% with higher scores for transversal healing. Morphological and anatomical modifications of Linum were related to mechanical properties and healing ability. Alongside with an increased understanding of wound healing in plants, our results highlight their possible impact on textile quality and fibre yield.

Influence of mechanical damage and storage on various quality aspects of potatoes

The aim of this study was to determine the effects of mechanical damage on both the contents of dry matter and chlorogenic acid and the degree of blackspot for five cultivars of potatoes of various earliness groups. The study was conducted immediately after the harvest as well as after two, four and six months of storage under constant conditions (air temperature +4 °C and RH 95%). Mechanical damage leads to a greater accumulation of chlorogenic acid and increases the tubers’ susceptibility to blackening, irrespective of the earliness group. The duration of storage significantly determines the dry matter content of chlorogenic acid and the susceptibility to blackening of raw tuber flesh to the greatest extent for cultivars of the medium-early group. A significant (P < 0.01) correlation was demonstrated between the dry matter and chlorogenic acid contents and the degree of blackspot, which was higher on damaged tubers.

Composite pressure vessels for hydrogen storage in fire conditions: Fire tests and burst simulation

A type IV composite pressure vessel subjected to fire may burst because of the degradation of the outer layers, but when the inner pressure is less than a critical value, leak is observed instead of burst. This phenomenon is due to the heat transfer through the composite shell which leads to liner melting. In order to characterize this failure mechanisms, engulfing fire tests have been performed in the framework of the FireComp project whose objective is to understand and simulate the fire performance of hydrogen storage. An experimental set-up has been implemented to expose the cylinders to fire by the means of gas injectors. A simple FE model has been developed to simulate the coupled effects of mechanical damage and of temperature. This approach is found to accurately predict the time to burst of the composite tank, as well as the transition between burst and leak.

Resistance of a nonwoven geotextile against mechanical damage and abrasion

The installation procedures (which induce mechanical damage) and abrasion can cause unwanted changes on the properties of the geotextiles. In this work, a nonwoven polypropylene geotextile was subjected to three degradation tests: (1) mechanical damage, (2) abrasion and (3) mechanical damage followed by abrasion (successive exposure). The damage caused by the degradation tests was evaluated by tensile, tearing and static puncture tests. Based on the changes occurred in the mechanical properties, reduction factors were determined. Results showed that the degradation tests provoked relevant reductions in the mechanical strength of the geotextile (higher reductions in the successive exposure to both degradation tests). The reduction factors for the combined effect of mechanical damage and abrasion obtained in the successive exposure to both degradation tests were different (slightly higher) than those obtained by the traditional methodology (determination of reduction factors separately for each degradation test and further multiplication).

Tillage Reduces Survival of Grape Berry Moth (Lepidoptera: Tortricidae), via Burial Rather Than Mechanical Injury.

The grape berry moth, Paralobesia viteana (Clemens), is a key pest of vineyards in eastern North America that overwinters as pupae in leaf litter on the vineyard floor. This presents an opportunity for tillage to disturb and bury the pupae, providing a potential nonchemical approach to control of this pest. Using a Lilleston-style rotary cultivator, we determined the distribution of pupae within the soil profile after single tillage passes, measured the type and severity of damage inflicted on pupae, and investigated how these effects on pupae influenced their survival. Survivorship of pupae recovered from the vineyard immediately after tillage and held until emergence was not significantly different from those recovered from an untilled control area, indicating little effect of mechanical damage on this pest. However, a single pass of the tillage implement buried three-quarters of pupae under at least 1 cm of soil. A laboratory experiment to recreate these conditions resulted in significant increase in mortality when pupae were buried in more than 1 cm of sand. We conclude that 1) interference with adult emergence of diapausing pupae via burial is the primary mechanism by which tillage controls grape berry moth, and 2) efforts to optimize the impact of tillage on grape berry moth populations should focus on maximizing the number of pupae buried. We discuss the potential integration of tillage into different vineyard management systems to enhance pest management.

Bean grain hysteresis with induced mechanical damage

ABSTRACT This study aimed to evaluate the effect of mechanical damage on the hysteresis of beans with induced mechanical damage under different conditions of temperature and relative humidity. Beans (Phaseolus vulgaris L.) harvested manually with 35% water content (w.b.) were used. Part of this product was subjected to induced mechanical damage by Stein Breakage Tester and controlled drying (damaged and control sample), for sorption processes. The sorption isotherms of water were analyzed for different temperature conditions: 20, 30, 40 and 50 oC; and relative humidity: 0.3; 0.4; 0.5; 0.7 and 0.9 (decimal). Equilibrium moisture content data were correlated with six mathematical models, and the Modified Oswin model was the one that best fitted to the experimental data. According to the above mentioned isotherms, it was possible to observe the phenomenon of hysteresis of damaged and control samples, and this phenomenon was more pronounced in control ones.

English

Seed quality control is becoming increasingly important, since the market is increasingly competitive. The planting operation process should occur in order to avoid mechanical damage, which may affect the seed quality. This study aimed to evaluate the effect of mechanical damage caused by meter mechanisms (mechanical and pneumatic) on physical and physiological quality of corn seeds. The experiment was carried out in a Rhodic Hapludox, Southeast Brazil. A randomized block design with 2 &times; 3 factorial scheme (metering mechanism x seed shape) was used. The corn variety used was a corn hybrid SYN5R27. The seed samples were collected before and after the planter run, and the seed performance was evaluated by germination, accelerated aging, cold test, emergency in the soil and determination of mechanical damages with iodine. The metering mechanisms (mechanical and pneumatic) did not affect the seed quality, except for the saturated cold test that estimates the germination potential of the seeds under adverse conditions. Due to a better adaptation of the disks, the flat seeds presented less damage. &nbsp; Key words: Mechanical meter, pneumatic planter, physiological quality, planting performance.

Susceptibility and Interactions of Drosophila suzukii and Zaprionus indianus (Diptera: Drosophilidae) in Damaging Strawberry.

Drosophila suzukii (Matsumura) has been recently detected causing damage to strawberries in Brazil. Infestation in strawberry culture has often been observed jointly with the presence of Zaprionus indianus Gupta. This study investigated the susceptibility of strawberries at three ripening stages to infestation of D. suzukii and Z. indianus and their interaction. In the laboratory, strawberries cv. Albion at different ripening stages (green, semi-ripe and ripe) were exposed to D. suzukii and Z. indianus for 24 h in choice and no-choice bioassays. Additionally, we evaluated the effects of mechanical damage incurred artificially or by D. suzukii oviposition on Z. indianus infestation. In no-choice bioassay, there were no significant differences in fruit susceptibility to D. suzukii infestation at different ripening stages. However, in choice bioassay, D. suzukii adults preferred to oviposit on R fruit. The presence of mechanical damage did not increase susceptibility of fruit to D. suzukii oviposition. For Z. indianus, there was greater susceptibility of R fruit in relation to SR and G fruit in both the choice and no-choice bioassays. There was a significant and positive interaction of mechanical damage and damage caused by D. suzukii to R fruit and infestation by Z. indianus, which was not observed in SR and G fruit. Although infestation of Z. indianus is related to attack damaged or decaying fruit, this work shows that this species has the ability to oviposit and develop in healthy strawberry fruit with and increased infestation level when the fruit has damage to its epidermis.

Combined meso-scale modeling and experimental investigation of the effect of mechanical damage on the transport properties of cementitious composites

The transport properties of cementitious composites such as concrete are important indicators of their durability, and are known to be heavily influenced by mechanical loading. In the current work, we use meso-scale hygro-mechanical modeling with a morphological 3D two phase mortar-aggregate model, in conjunction with experimentally obtained properties, to investigate the coupling between mechanical loading and damage and the permeability of the composite. The increase in permeability of a cylindrical test specimen at 28% aggregate fraction during a uniaxial displacement-controlled compression test at 85% of the peak load was measured using a gas permeameter. The mortar's mechanical behavior is assumed to follow the well-known compression damaged plasticity (CDP) model with isotropic damage, at varying thresholds, and obtained from different envelope curves. The damaged intrinsic permeability of the mortar evolves according to a logarithmic matching law with progressive loading. We fit the matching law parameters to the experimental result for the test specimen by inverse identification using our meso-scale model. We then subject a series of virtual composite specimens to quasi-static uniaxial compressive loading with varying boundary conditions to obtain the simulated damage and strain evolutions, and use the damage data and the previously identified parameters to determine the evolution of the macroscopic permeability tensor for the specimens, using a network model. We conduct a full parameter study by varying aggregate volume fraction, granulometric distribution, loading/boundary conditions and “matching law” parameters, as well as for different strain–damage thresholds and uniaxial loading envelope curves. Based on this study, we propose Avrami equation-based upper and lower bounds for the evolution of the damaged permeability of the composite.