Influence Of Mechanical Damage Research Articles

Mechanistic insights into single crystal cadmium whisker growth on Ti2Cd intermetallic

Metal whisker growth poses a significant reliability threat to electronic devices. Previous investigations have predominantly focused on metal platings and alloy solder samples, yet the intricate factors involved have yielded inconsistent comprehension of the phenomenon. To achieve a comprehensive understanding, exploring intermetallic compounds (IMCs) may offer a novel standpoint. Herein, we present the first report on the growth of single crystal cadmium (Cd) whiskers on Ti2Cd IMC, accompanied by the characterization of their composition, crystal structure, and morphological features. Furthermore, the influence of mechanical damage and temperature on the whisker growth is examined. Ball milling induces the decomposition of Ti2Cd, liberating active Cd atoms with elevated chemical potentials that consequently feed the whisker growth. These findings augment the existing knowledge on the topic of the metal whisker growth and provide fresh perspectives and references for further investigations in this field.

Modeling damage to the solid electrolyte matrix in composite electrodes: role of ionic conductivity

Solid composite electrodes play a critical role in all-solid-sate-batteries, but intercalation-induced expansion of the active materials will cause damage in the matrix and affect the performance of battery. In this work, damage evolution in the solid electrolyte (SE) matrix related to migration of ions/electrons in SE matrix, transport of species in electrode particles, local current densities at the SE/active materials interface, and mechanical deformation of the structure is investigated based on the non-local damage approach. The influence of mechanical damage on the electrochemical performance is modeled by coupling the damage variable and ionic conductivity of the SE. The results indicate that for low ionic conductivity, the damage of the SE matrix is inhomogeneous across the composite electrodes, while for high ionic conductivity, the damage of the SE matrix is uniform. We also investigate the effect of damage on the electrochemical performance of battery and it is shown that capacity loss is significant for low ionic conductivity, but shows little variation under high ionic conductivity.

A numerical simulation method of nonlinear magnetic flux leakage testing signals for nondestructive evaluation of plastic deformation in a ferromagnetic material

Nonlinear Magnetic Flux Leakage Testing (MFLT) method is a relative new non-destructive testing (NDT) technique for inspection defect or micro damage in structure of ferromagnetic material by measuring the leakage magnetic field during an alternative magnetization process. To enhance the nonlinear MFLT technique, a numerical tool for simulating the inspection signal is very important in views to clarify the detection mechanism and to improve the detection efficiency. However, most of the simulation methods on magnetic NDT problems solve problem without considering the hysteresis effects of ferromagnetic materials and is difficult to deal with the influence of mechanical damage. In this paper, a numerical scheme is proposed at first to simulate the nonlinear MFLT signals considering the nonlinearity and hysteresis characteristics of ferromagnetic materials based on the equivalent magnetic polarization approach and FEM-BEM hybrid method. The validities of the proposed method and the corresponding numerical code are proved by comparing the simulation results of a typical nonlinear MFLT problem with the experimental measured signals. Secondly, in order to cope with the influence of plastic deformation in material on the nonlinear MFLT signals, a magneto-mechanical coupling constitutive relation is proposed and applied to the developed numerical simulation code. Finally, the nonlinear MFLT signals of specimen with different plastic deformation are simulated with the developed numerical code and the influence mechanism of plastic deformation on nonlinear MFLT signals is discussed based on the numerical results. The results reveal that the distortion of nonlinear MFLT signals mainly due to the magnetic remanence coefficient of material which can be significantly influenced by micro damage such as the plastic deformation.

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.

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.

THE MAIN GAS PIPELINES MECHANICAL DAMAGE INFLUENCE ON SAFE OPERATION / MAGISTRALINIO DUJOTIEKIO MECHANINIŲ PAŽEIDIMŲ ĮTAKA SAUGIAM EKSPLOATAVIMUI

The influence of mechanical damage of the gas transmission pipelines on safe pipelines operation was researched in the article. The paper presents the main pipelines damage types with actual parameters and influence on operational parameters. The main pipeline Kaunas – Kaliningrad part, which was removed as no longer usable, was analysed. This damaged part was removed and changed to a new part by a responsible company. The hardness measurement and micro hardness measurement, chemical analysis, impact strength test, metallography analysis with an optical microscope were used in experiments. The analysed pipeline part was also regenerated by the computer software ANSYS, which works by the finite elements method. Straipsnyje nagrinėjama magistralinių dujotiekių mechaninių pažeidimų įtaka saugiam jų eksploatavimui. Darbe pateikti pagrindiniai vamzdynų pažeidimo tipai su jiems būdingais bruožais ir įtaka eksploataciniams parametrams. Ištirta magistralinio dujotiekio Kaunas – Kaliningradas dalis, kuri buvo pašalinta, kaip nebetinkama naudojimui. Tyrimams pasitelktas kietumo ir mikrokietumo matavimas, cheminės analizės tyrimas, smūginio tąsumo bandymas. Mikrostruktūros tyrimams naudotas optinis mikroskopas. Tiriamasis objektas buvo atkurtas kompiuterinės programos, veikiančios baigtinių elementų metodu, ANSYS erdvėje.

Corrosion in Aluminium Cans with Grape Juice – Influence of Mechanical Damage

The consumption of canned food products from dented cans is not recommended by surveillance and consumer protection agencies due to the possibility of aluminium pick up, which may migrate from package to food/beverage. However, it is necessary to raise scientific data that will support any decision concerning the consumption of this kind of food, especially when the percentage of undernourished persons all over the world is considerable. Drawn and wall ironing–type aluminium cans with 330 ml of ready‐to‐drink grape juice, under three different controlled conditions of can damage as well as without damage, were evaluated for 1 year at 35°C. Aluminium migration, internal pressure and can internal surface appearance were periodically evaluated in order to monitor the package/beverage interaction. The results showed very small variation on the can internal surface appearance and pressure. Even after storage for 365 days, no can presented perforation, although the aluminium migration was increased. The highlight of this work is that after 1 year, for all the evaluated damage conditions, the ready‐to‐drink grape juice in aluminium cans could be considered adequate for human consumption in terms of metal migration from packaging. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Experimental Investigation of Mechanical Damage in Geogrids

This paper presents the results of a comprehensive experimental program for investigating the influence of mechanical damage on the load-displacement behavior of geogrids. Unconfined tension tests, pullout and direct shear tests were carried out on intact and damaged specimens. Natural or artificial damages were produced either by imposing heavy compaction procedures in the laboratory or by simply cutting one or more geogrid elements. It is concluded that natural damage in the geogrid may be more pronounced when aggressive compaction methods are used with coarse grained soils. Fine grained soils did not show a significant strength reduction even when subjected to heavy compaction in the laboratory. Under pullout loading, artificial damage was also noted to be of little significance for fine soil (silty clay). Rupture of the geogrid’s transverse elements led to a significant pullout strength reduction. These transverse elements are responsible for anchoring the geogrid within the soil mass. However, under unconfined tensile load, these transverse elements are responsible only for the grid’s geometrical configuration and their rupture did not induce a significant strength loss. In direct shear, the position of the geogrid relative to the potential failure surface was shown to be an important factor.

Influence of mechanical damage on fluid flow patterns investigated using CT scanning imaging and acoustic emissions techniques

[1] In order to get some insight into the influence of mechanical deformation on fluid flow patterns, we performed series of X-ray CT scanning runs during capillary imbibition experiments to image the water front displacement in Bentheim sandstone samples. A three steps procedure was followed: 1) intact rock samples were tested, 2) the samples were deformed in creep experiments under triaxial conditions with recording of acoustic emissions, 3) the deformed samples experienced a second capillary imbibition test with CT scanning imaging. Using image analysis tools, relevant flow parameters like the height, velocity and curvature of the water front were measured. Stress-induced damage had a significant impact on the flow patterns. However contrasted results were obtained: localized damage evidenced by acoustic emissions clustering resulted in one experiment in local disturbance of the flow patterns, whereas in the second one a fracture detected by CT scan did not modify the local flow geometry.

Analysis of wirebonding techniques for contacting high concentrator solar cells

The results of the wirebonding technique application to make connections on high concentrator solar cells are presented in this paper. The most usual wirebonding techniques in current microelectronic industry have been analyzed (i.e., aluminum wedge bonding and thermosonic gold ball bonding). In the first part of the paper the influence of wirebonding processes on solar cell performance is discussed theoretically. The theoretical approach is followed by a comprehensive experimental analysis, which focuses on: a) the influence of mechanical damage on the device I-V curve; b) bondability analysis; c) the influence of wirebonding damage on device lifetime; d) analysis of the electrical resistance of the connection. Finally some conclusions of practical interest are drawn and the main results of the work are summarized.

A study of the coupling between the phenomena of water absorption and damage in glass/epoxy composite pipes

An analysis of the influence of moisture on the mechanical properties and kinetics of damage is presented. The material studied is a glass/epoxy laminate pipe for fluid circuit applications. The tubular specimens have been obtained by the filament-winding technique. In the first part of the paper, the diffusion law and the influence of mechanical damage on absorption are presented, while in the second part, the change in the kinetics of the damage is studied for various levels of water content. Mechanical tests, under tension and internal pressure with fixed ends, demonstrate an increase in the rate of damage as a function of water content. The damage rate acceleration is taken into account in a multiaxial behaviour model. The effect of water content in the material is introduced into this model by using a damage-associated variable depending on the moisture level.

The Influence of Mechanical Damage to the Seed Coat on the Dormancy of Groundnut Seeds

The Influence of Mechanical Damage to the Seed Coat on the Dormancy of Groundnut Seeds

Influence of mechanical damage and repeated infestation of sorghum on its resistance to Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Abrading the pericarp rendered resistant sorghum cultivars as susceptible as abraded susceptible cultivars to attack by Sitophilus oryzae (L.). A previous exposure of selected sorghum cultivars to S. oryzae broke down pericarp resistance factor(s). Damage to sorghum kernels during harvesting and handling could therefore destroy resistance to rice weevil attack.

Influence of Mechanical Damage and Fungicide Seed Treatments on Germination and Stand with Cottonseed1

Mechanical damage to the seed coat of cotton (Gossypium hirsutum L.) seeds may occur during harvesting, ginning, and processing. The extent of damage vanes considerably among seed lots and it is impossible to remove all damaged seed while processing seed for planting. Fungicide‐treated and non‐treated seed with damaged seed coats germinate slower and produce poorer stands than seed with nondamaged seed coats. The percentage germination at standard temperatures in the laboratory and the stands and seedling growth in the greenhouse were inversely related to the extent of damage to the seed coat of acid‐delinted cottonseed. Scratches or cracks in the seed coats that did not expose the embryonic tissues adversely affected germination and stand less than did damage that exposed the embryonic tissues. Coating cottonseed with fungicides improved the performance of all seed classes, but the most improvement was obtained from seed with a damaged seed coat. However, no fungicide treatment completely compensated for the damage to the seed coat.

Influence of mechanical damage on avalanche breadown in silicon pn junctions : A. Goetzberger and R. H. Finch. Solid State Electron.7, 543 (1964)

Influence of mechanical damage on avalanche breadown in silicon pn junctions : A. Goetzberger and R. H. Finch. Solid State Electron.7, 543 (1964)

Influence of mechanical damage on avalanche breakdown in silicon pn junctions

Diodes exhibiting uniform avalanche effect were mechanically damaged by scratching with a silicon carbide tool. The breakdown voltage in the damaged regions was found to be increased in n + p junctions and decreased in p + n junctions. Annealing at temperatures of 600°C and above resulted in gradual restoration of the original diode properties. It is concluded that about 2·5 × 10 17 donors are introduced into the space charge layer by the mechanical damage.