Degree Of Mechanical Damage Research Articles

Compressive strength and microscopic mechanism of nanosilica modified recycled aggregate mortar

Due to low density, large pores, and numerous cracks, recycled aggregate mortar has defects of lower fluidity and lower strength compared to natural aggregate mortar. In order to modify inherent defects of recycled aggregates, nanosilica (NS) with different dosages (0%, 0.6%, 1.2%, 1.8%, 2.4% and 3%) was added to recycled aggregate mortar (RNC), and 40% natural sand in RNC was replaced by recycled aggregates. Then consistency test, compressive strength test and microscopic tests (SEM, EDS and XRD) were conducted to investigate working performance and microscopic mechanism. It was found that the addition of NS can improve the flowability of RNC, and the consistency value reaches the maximum (53 mm) while NS content is 2.4%, which increases by 14% comparing to the specimen without NS. The compressive strength of RNC increases and decreases with increasing NS content in the ranges of 0–1.8% and 1.8–3% respectively, and compressive strength is 3.3 and 5.9 MPa at curing ages of 7 d and 28 d respectively while NS content is 1.8%, which increase 50% and 14% comparing to the specimen without NS. Meanwhile, the consistency value of the specimen with NS content of 1.8% is 51 mm, which is close the maximum value corresponding to NS content of 2.4%. For that, 1.8% is suggested as the optimal content of NS. Moreover, the addition of NS can reduce the brittleness index and mechanical damage degree, and enhance the energy absorption effect. Microscopic analysis reveals that NS can not only fill the inherent cracks and pores of recycled aggregates, but also promote cement hydration reaction, and more hydration products (C-S-H) can efficiently reduce the cracks and pores of recycled aggregates. It is believed that the finds of this paper can provide theoretical support for the application of recycled aggregates in practical engineering.

Research on damage optimization of copper-carbon gradient composite materials for current-carrying friction

To meet the demand for damage optimization of current-carrying friction materials and based on the uneven distribution characteristics of damage, copper-graphite gradient composite materials were prepared using spark plasma sintering technology. These materials were paired with H62 brass, conducting damage optimization studies on copper-graphite gradient composite materials using a self-made current-carrying friction test machine. The results indicate that the copper-graphite gradient composite materials possess excellent current-carrying performance. With an increase of graphite content, the degree of mechanical damage and arc damage on the worn surface is optimized. The friction coefficient and wear rate of the material significantly decrease. When the content of graphite in the material is 5 wt% − 10 wt%, The material's damage optimization reaches the best and the wear rate is 9.7 × 10−4 mg·m−1. At this point, the predominant form of damage to the material is plastic deformation.

Effects of different vibration spectrum shapes on mechanical damage of postharvest Huangguan pear during transportation

Mechanical damage of the horticultural produce during postharvest transportation is an important criteria for fruit sorting and grading. The vibration during transportation has a significant effect on the mechanical damage of the fruit. In this study, the effect of different vibration spectrum shapes on mechanical damage of Huangguan pear (Pyrus bretschneideri Rehd, cv. Huangguan) was investigated. Four acceleration spectrums (spectrum Ⅰ, spectrum Ⅱ, spectrum Ⅲ, and spectrum Ⅳ) with same vibration level and different shapes were evaluated. The power spectral density (PSD) amplitude in the resonant region was in the order of spectrum Ⅰ > spectrum Ⅱ> spectrum Ⅲ > spectrum Ⅳ. The change in appearance, physiological properties (respiratory rate and weight loss), and mechanical properties (firmness and elastic modulus) of the pears were evaluated after vibration. Results showed that vibration resulted in quality deterioration of pear. Compared to the control group, respiratory rate and weight loss of the pears increased while the flesh firmness and elastic modulus of the pears decreased after vibration. The mechanical damage became more serious as stacked position increased. The effect of spectrum shape on the mechanical damage of pear was also obvious. Different degree of mechanical damage was observed under spectrum Ⅰ, spectrum Ⅱ, spectrum Ⅲ, and spectrum Ⅳ vibration. The higher the acceleration PSD in resonant region, the more serious the mechanical damage of pear. In comparison with the control group, pear under spectrum Ⅰ effect showed the most mechanical damage and the pear under spectrum Ⅳ effect had the minimum mechanical damage. Furthermore, S−Grms curves (damage area - vibration level) showed a clockwise rotation from spectrum Ⅰ to Ⅲ vibration. This study reveals the mechanical damage mechanism of pears based on acceleration spectrum shape and provides guidance for postharvest loss reduction using simulated test.

Design Of Environmental Conditions Of Transportation Simulation Instruments On Tomato (Solanum Lycopersicum)

Based on data from Badan Pusat Statistik (BPS) in 2017-2018, the tomato productivity in Indonesia has seen a year-on-year increase of 10% and 19%. However, during the transportation process of agricultural commodities, excessive vibration can lead to damage of tomato commodities. Therefore, the purpose of this study is to develop an environmental data recording device using Arduino technology, and to assess its performance by simulating vibration during transport. The aim is to ensure proper handling and storage of tomato commodities in the distribution process. The designs used are programming designs, functional designs, and structural designs. The results showed that the design of an arduino-based environmental data recording instrument, calibration results between the DHT22 sensor (temperature) and a digital hygrometer yielded a correlation equation value of y = 1.0475x – 1.5575, R2 for the DHT22 sensor was 0.9885, and for the calibration results between the vibration sensor and the vibrating table as a calibrator obtained a correlation equation value of y = 1.9471x-101.24, the calibration R2 value was 0.8088, the instrument accuracy performance test results were obtained by 80%. The stability test results of reading past the setting point, the control speed is 4.04 minutes, the result of the reliability coefficient value (r11) is 0.90. The reliability coefficient value from the stability test results is included in the very high reliability category, the system response at a setting point of 150 RPM takes 63 seconds and the system response at a setting point of 200 RPM takes 71 seconds. characteristics that occur in tomatoes during the transportation simulation process where at 100 RPM the test was carried out, the tomatoes experienced a collision and only a few were bruised due to the shock from the transportation simulation the tomatoes were damaged and collided between the tomatoes in the box, the greater the vibration received by the tomatoes on during the transportation simulation, the more tomatoes will experience physical damage.Test results on tomatoes with a degree of mechanical damage (bruises) due to vibration during transportation. In stack 1 100 RPM there was no damage to the fruit while the biggest bruising occurred in stack 3 with 200 RPM.

Parameter Analysis and Field Tests of a Double Crank Multi-Rod under Plastic-Film Hill-Drop Mechanism Potato Planter

The new technology of filming in autumn and planting directly through the plastic film in spring is an effective water-saving method and drought-resistance commercial potato production. However, filming first and then planting is not compatible with the working of known potato mulching planters. In order to realize the hill-drop under plastic-film in potato seeding, a double crank multi-rod mechanism has been designed and a prototype built. Using computer-aided design software, the effect of several kinematic parameters upon the motion of the planter dibber has been systematically investigated. A mechanism with optimized parameters has then been built and tested in a dry farming area of the Loessal Plateau of Northwest China. Results showed that the qualified rate of sowing depth under plastic-film was 92%, the rate of hole dislocation was 5%, the qualified rate of hole distance was 88% and the mechanical-damage degree of plastic-film lighting surface was 52.1 mm/m2. The proposed planter meets all the agronomic requirements of hill-drop on plastic-film potato planting, and has the potential to perform well in other geographic areas, where comparable farming conditions exist.

The effect of cardiopulmonary bypass on the morphological characteristics of red blood cells and the gas transmission function of blood

Investigate the effect of extracorporeal circulation on the erythrocyte morphology, the intensity of gas exchange in the body tissues of the patient was determined before the operation, during the operation and during the postoperative treatment using morphometric analysis of the form of erythrocytes. It was established that during the operation with artificial blood circulation, the ratio of the voltage of oxygen and carbon dioxide in arterial and venous blood changes, indicating a shift in the oxygen capacity of the blood. Since the oxygen concentration in the oxygenator is known and under constant control, a decrease in the oxygen capacity of the blood reflects the intensity of tissue respiration on the one hand, and the degree of mechanical damage to red blood cells on the other. The intensity of tissue respiration was judged on the basis of a previously unknown fact that the form of erythrocytes depends on the degree of their saturation with oxygen. It is noted that blood, saturated with oxygen (arterial) under normal conditions of gas exchange in the lungs, is 90-95% composed of small red blood cells (villous length 0,3-0,4 μm), venous blood is represented mainly by large vorous forms of red blood cells (villous length 0,4-1 μm). The form of red blood cells is reversible and changes both after passing through the lungs (oxygenator), and after gas exchange in the tissues. The inhibition of oxygen consumption by red blood during perfusion indicates a change in the metabolic processes, shape and resistance of red blood cells, which allows a more complete assessment of the pathophysiological changes that occur in the body in response to perfusion. The proposed methods of morphometric analysis of erythrocytes, as well as determining their osmotic resistance, can serve as express methods for analyzing red blood during heart operations using extracorporeal circulation, in order to correct it in time and replenish it.

Assessment of the tissue respiration intensity after cardiopulmonary bypass by studying erythrocytes morphology

Introduction.It was previously unknown that the form of erythrocytes depends on their interaction with oxygen. The form of red blood cells is reversible and changes both after passing through the lungs (oxygenator), and after gas exchanges in the tissues.Purpose of the study. In order to study the effect of cardiopulmonary bypass (CPB) on the erythrocyte morphology, the intensity of gas exchanges in the body tissues of the patient was determined using morphometric analysis of the form of erythrocytes.Material and methods.To achieve this goal, we developed a method for the morphometric analysis of erythrocytes «in vitro». Blood test was performed before surgery, on the 10th and every 30thminute of CPB, 12 hours after surgery.Results.Using this fact, we studied tissue respiration intensity. We found that normal arterial blood contains 85 % [80–95 %] red blood cells covered with small «villi» (0.3–0.4 μm), whereas venous blood consists mostly of «large-villous» erythrocytes (length of the «villi» 0.4–1.0 μm, 70 % [6–80 %]). During pairwise comparison we found the significant difference in the proportion of «large-villous» red blood cells in arterial blood before (15 % [5–20 %]) and after (35 % [20–50 %]) CPB. Partial pressure of oxygen and carbon dioxide changes throughout CPB and it shows changes in oxygen carrying capacity of blood. Decrease in the oxygen capacity of the blood reflects the intensity of tissue respiration on the one hand, and the degree of mechanical damage to red blood cells on the other.Conclusion.Heart surgery in infrared conditions lead to pronounced shifts in the ratio of discocytes and pathological forms of red blood cells in the blood. Inhibition of the red blood oxygen consumption during CPB indicates changes in the metabolic reactions, erythrocytes morphology and functionality. These data give us more complete understanding of the pathophysiological changes throughout CPB. The proposed method of erythrocytes morphometric analysis can be used as an express blood test in heart surgery with CPB, enabling better understanding of red blood state.

Mechanism Damage to Mode-I Fractured Sandstone from Chemical Solutions and Its Correlation with Strength Characteristics

The fracture toughness of rock is very important in rock cutting, blasting, and hydraulic fracturing for tunnel excavation. To evaluate factors that reduce rock fracture toughness, we emulated the environment of joint rock in the hydro-fluctuation belt of a typical bank slope in the Shanxi Tong Chuan reservoir region. We tested long-term immersion of sandstone samples in different chemical solutions to determine the resulting mechanical characteristics and damage degradation. Variations in the physical and mechanical properties of the samples were analyzed under the effects of the chemical solutions. Experimental results show that the sandstone was significantly damaged by the chemical solutions, but its peak strain increased, and different chemical solutions had distinct influences on the degree of mechanical damage. These differences varied with the acid–base properties of the solutions. Also, there were clear consistencies among the solutions in the degree of their damage to mechanical parameters, physical parameters, and ion concentrations. Therefore, we were able to obtain correlations among the physical and mechanical parameters of the sandstone samples, damage variables, and the ion concentrations of calcium and magnesium. The surfaces of the samples were seriously degraded after being subjected to the corrosive effect of various chemicals; for example, there were different amounts of holes and pitting corrosion. The sizes of the holes and the degree of surface pitting gradually increased with an increase in corrosion time.

Inženjerskogeološke odlike terena opštine Gadžin Han

Engineering geological features of the terrain are one of the important factors for land use. Hence, engineering geological maps are the basis for good spatial and urban planning. Knowing location of unstable zones we can avoid major damage. Research carried out on the part of the municipality of Gadžin Han shows that it is endangered by landslides. The causes of landslides are numerous, mostly the lithology, degree of mechanical damage (cracking and weathering), morphology, hydrology and hydrogeology, vegetation etc. The most vulnerable part is Zaplanje area where the largest number of landslides is registered. This paper is overview of engineering geological features of municipality Gadžin Han with special review of landslides and falls.

Brief adult respiratory system health status scale-community version (BARSHSS-CV): developing and evaluating the reliability and validity

BackgroundThe evaluation of respiratory system health status in hospitalized patients is usually based on many laboratory examinations and imaging examinations. Medical examinations require a lot of manpower, material resources, financial resources, and may cause a certain degree of mechanical damage and radiation damage. It is not easily used widely and economically to assess the respiratory health status of community adults. Therefore, researchers developed a brief adult respiratory system health status scale-community version (BARSHSS-CV) and tested its reliability and validity.MethodsUsing clinical characteristics and pathogenic factors of respiratory system diseases as a theoretical basis and through reference to relevant literature, researchers developed an initial scale. A randomized cluster sampling strategy was used to recruit adults in the communities of Baoding City, Shijiazhuang City, Cangzhou city and Chifeng City in China. Researchers randomly selected 1 district from each city. Subsequently, 4 communities were respectively randomly selected from 4 districts. Then, researchers conducted the questionnaire survey in 4 communities. Finally, researchers investigated 615 community adults. 584 valid questionnaires were recovered. By applying exploratory factor analysis, confirmatory factor analysis, content validity index, Cronbach’s α coefficient, mean inter-item correlation coefficient and test-retest reliability, researchers tested the reliability and validity of scale and created the final BARSHSS-CV.ResultsBARSHSS-CV Cronbach’s α=0.951, content validity = 0.933, test-retest reliability = 0.963 and factor cumulative contribution rate = 67.168% by exploratory factor analysis. By confirmatory factor analysis, Chi square value (χ2) was 442.117, degrees of freedom (df) was 161, Chi square value/degrees of freedom (χ2 /df) was 2.746, root-mean-square error of approximation (RMSEA) was 0.065, goodness of fit index (GFI) was 0.902, incremental fit index (IFI) was 0.955, comparative fit index (CFI) was 0.955, normed fit index (NFI) was 0.931, Tueker-Lewis index (TLI) was 0.947. BARSHSS-CV consisted of 20 items and 3 dimensions.ConclusionsBARSHSS-CV with good test-retest reliability and content/construct validity is a brief and economical tool for assessing the state of respiratory system amongst adult communities. BARSHSS-CV may help medical staff in community primary medical institutions quickly, conveniently and economically assess the status of respiratory system and the main problems of respiratory system in community adults.

Analysis of Relationships Between Three-Dimensional Magnetic Memory Signals and Artificial Defects Under Tensile Load

Abstract This paper mainly discusses the relationships between three-dimensional magnetic memory signals and artificial defects under different load levels. The correlations between the defect signal characteristic parameters and applied stress were analyzed. The magnetic signals at the surface of FV520B steels were measured by a 3D magnetic sensor. It has been concluded that three-dimensional magnetic signals had different detection sensitivity to the defects in different directions, and the defects can be accurately recognized based on the distinctive signal features. Additionally, the peak value of the tangential component and the peak-to-peak value of the normal component (i.e., Bxp and Bzp-p) presented different characteristics in elastic and plastic deformation stages with the increase of applied stress. The amplitude changes of the tangential component and maximum gradient value of the normal component (i.e., ΔBx and KG) were capable of estimating the mechanical damage degree of ferromagnetic materials.

PALYNOLOGY OF MARINE BLACK SANDS FROM THE YAROSHIVKA QUARRY, UKRAINE – A CONTRIBUTION TO MIDDLE EOCENE PALAEOGEOGRAPHY OF NORTHERN UKRAINE

Black sads of the Yaroshivka Beds (Middle Eocene, Lutetian) that directly overlie granitoids exploited in the Yaroshivka Quarry (northeastern peripheries of the Ukrainian Shield) have been studied for palynology. This study was conducted with an aim of palaeoenvironment reconstruction that could contribute to the palaeogeography of Ukraine in the Palaeogene. Deposits studied yielded both marine and continental palynomorphs. The former consist mainly of dinoflagellate cysts, Prasinophyceae algae, and acritarchs. Terrestrial palynomorphs are mainly bisaccate pollen grains. Representatives of both palynomorph groups are immature but they show high degree of mechanical damage. Particularly large specimens of chorate dinoflagellate cysts are almost exclusively preserved as torn-off fragments. Small proximate dinoflagellate cysts and tiny acritarchs are usually complete. Palynomorph assemblages described were interpreted as typical for marine, high energetic sedimentary setting located within a proximal zone of terrestrial influences. Subsequent progression of the Eocene transgression led to a complete inundation of the Ukrainian Shield in the area of our study. As a result, different palaeoenvironmental conditions appeared. They caused pronounced changes in palynofacies and palynomorphs assemblages found in the strata transitional to the overlying Kyiv Fm.

Addressing fouling build-up through advanced coatings

The industrial need for anti-fouling coatings is significant and continues to grow. Whilst applications are enormously diverse; ranging from blades on gas and wind turbines to ship hulls, and from aircraft wings to the inside of oil pipelines; one factor remains constant – the challenge of producing a coating which is both anti-fouling and durable. Many commercially available products offer anti-fouling characteristics or durability, but not both. Some of the best performing options are based on fluorine chemistry and with legislative pressure likely to constrain the application of fluorinated materials, a new breed of hybrid materials is now emerging. TWI has been developing class leading solutions in this area. This article compares commercially available products and introduces an approach to testing that enables anti-fouling characteristics to be examined against the degree of mechanical damage. Results indicate that products with high initial anti-fouling characteristics tend to degrade faster when exposed to abrasion. This emphasises the need to select the right coating for the right application.

Differentiation of Mechanical Damages of Rice Plants Using E-Nose

Abstract Plants change the emission of induced volatiles in response to damage and herbivore attack, and monitoring the change of such volatiles could provide a nondestructive means of plant health measurement. Current monitoring techniques for plant volatiles are time-consuming and costly. The main objective of this research is to figure out whether electronic nose (e-nose) technique can be used to differentiate rice plants with different degrees of mechanical damage. A portable e-nose (PEN2) is used to characterize and classify rice plants subjected to three degrees of mechanical damage compared with undamaged control plants. Principle component analysis (PCA), Linear discriminant analysis (LDA), Stepwise discriminant analysis (SDA), and Back-propagation neural network (BPNN) are applied to evaluate the data. Different degrees of damaged rice plants are better distinguished using LDA than using PCA. The average correction ratio of testing set of BPNN is 75%. The results obtained indicate that it is poss...

English

As different tomatoes have different locular cavities and a particular tomato materialis inhomogeneous, the effect of tomato internal structure on its mechanical properties and degree of mechanical damage may be significant during the gripping process with robot fingers. This was studied using the loading-unloading experiment as well as the observation of shelf life. The results showed that the plastic strain energy, Ep, peak force, Fmax and degree of elasticity, rc, were not significantly affected by the internal structure of three-locular tomato before its failure, but loading slope, rk, was. The degree of elasticity, rc and loading slope, rk, were significantly affected by the internal structure of four-locular tomato before its failure, but the plastic strain energy, Ep, and peak force, Fmax, were not. The compressibility e was the most important explanatory variable in the model of the degree of mechanical damage to tomato. The internal structure of four-locular tomato had a significant effect on its degree of mechanical damage, but the internal structure of three-locular tomato does not. Excluding the covariates, at the same compressibility, the degree of mechanical damage was greatest under the condition of F*CW and lowest for F*L their difference was 21.3%. The discrepancy of the medium degree of mechanical damage was slight under the condition of T*CW andT*L, respectively.   Key words: Tomato, internal structure, mechanical properties, degree of mechanical damage, analysis of covariance.

New data of typomorphic features of diamonds from placers in North Timan

The morphological and spectral-optical properties of diamond crystals from placers in North Timan rivers have been studied with IR-spectroscopy and cathode luminescence methods. As a result, correlation between external characteristics of diamonds (size and degree of mechanical damage) and number of optically active centers has been revealed. The habit and the type of distribution of structural defects in diamond crystals studied are comparable with those in diamonds from the Archangelsk Region and North Timan’s placers. Based on the obtained data, origin issues and possible primary sources of diamonds from North Timan’s placers are discussed.

Study on the collision-mechanical properties of tomatoes gripped by harvesting robot fingers.

The data of collision-mechanical property of tomatoes gripped by robot fingers are important for the gripping control of tomato harvesting robot. In the study, tests of controlling the fingers to grip tomatoes were conducted to ascertain the effects of input current, motor speed and impact positions on the impact force of fingers and maximum deformation of tomatoes. The input current of the motor ranged from 1200 to 2100 mA, the motor speed from 25 to 3000 rpm and the three impact positions as follows, 1 (radial arm), 2 (sloping at an angle of 22.5° to the radial arm) and 3 (sloping at an angle of 45° to the radial arm). The results shown that under the condition of the same motor speed and input current, the peak impact force on the radial arm, compared with other impact positions, was maximum, the deformation of tomato was the smallest and the degree of mechanical damage was the lowest too. Under different speed and input current conditions, when the fingers grip the tomato on the radial arm, the peak force of fingers and the maximum deformation of tomatoes were highly influenced by the motor speed and input current, especially the input current. The peak impact force and the maximum deformation of the tomato increased respectively with increase in the motor speed and input current and these followed cubic polynomial regression equations.

Efeito de diferentes graus de dano mecânico na qualidade fisiológica de sementes de sorgo

Diversas amostras de sementes de sorgo (Sorghum bicolor L. Moench.), cultivar BR 303, com diferentes níveis de danos mecânicos, foram analisadas com o objetivo de determinar o efeito imediato de danos mecânicos sobre a qualidade fisiológica. Os percentuais de dano mecânico foram determinados pelo teste de verde rápido, e a qualidade fisiológica das sementes pelos testes de germinação, envelhecimento acelerado, teste de frio, índice de velocidade de emergência e população inicial de plântulas. O experimento foi conduzido no Laboratório de Análises de Sementes da Embrapa-Centro Nacional de Pesquisa de Milho e Sorgo (CNPMS), em Sete Lagoas, MG. Através da análise de regressão, verificou-se que houve redução significativa da germinação e do vigor quando as sementes apresentaram até 5% de dano; de 5% a 15% de dano a redução na qualidade fisiológica não foi significativa. Acima de 15% até 23% de dano a germinação e o vigor sofreram um decréscimo de 22,5%, em comparação com o controle. O efeito prejudicial imediato dos danos mecânicos sobre a qualidade fisiológica das sementes de sorgo pôde ser detectada pelos testes aplicados.

Effect of freezing rate and programmed freezing on rheological parameters and tissue structure of potato (Cv. Monalisa)

Compression, shear and tension tests were carried out to determine the effect on potato tissues of different freezing rates (0.5, 1.25 and 2 °C/min down to −18 °C), thawing up to +20 °C at the same rates, and one, two, three or four successive freeze/thaw cycles. The effect of freezing rate on the zone of maximum crystallization was also examined, along with different combinations of programmed freezing, and the effect of prior cooling was assessed. Minimum alteration of the rheological behaviour of slowly thawed tissues was achieved by pre-freezing (3 °C for 30 min), slow cooling phases (0.5 °C/min) before and after the phase of maximum ice crystallization and quick freezing (2 °C/min) in the same phase. The shear test was found to be well suited to the study of these effects. Examination of the tissues by SEM revealed differing degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the samples. Coefficients of softening per freeze/thaw cycle were determined for the various rheological parameters, the highest value being given by the modulus of rigidity (17.75%).

Energy dissipation in highly compressed cylindrical bar specimens

Energy dissipated in a highly compressed 4340 steel cylinder is determined as a function of load time history. Analyzed in particular are the different material damage modes. Highly localized deformation can result in phase transformation of the metal in addition to other forms of failure such as yielding and fracture. Under large deformation, material response depends not only on strain rate but also the degree of mechanical damage. These effects are assessed quantitatively by an energy balance approach and the results compare favorably with available experimental data. The energy transfer associated with the change in material microstructure due to phase transformation is calculated. This can be identified with localized deformation bands which have also been observed in explosively fragmented bodies.