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Search results for: MUSCLE FATIGUE
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Three-Dimensional Fractography for Conventional and Additive Manufactured Steels After Bending-Torsion Fatigue
PublicationIn this study, fracture surface topography parameters were measured to investigate the effects of multiaxial loading. In order to assess the metrological aspects of fracture for notched specimens made of high-strength steels processed by both conventional and additively manufacturing (AM) techniques, an optical surface profilometer was used. Three bending moment to torsion moment ratios (B/T) were studied, i.e. 2, 1 and 2/3. The...
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Laser Beam as a Precision Tool to Increase Fatigue Resistance in an Eyelet of Undercarriage Drag Strut
PublicationThe article contains the results of tests on a laser-processed eyelet of undercarriage drag strut to increase its fatigue strength. Laser processing concentrated on both sides around the hole of eye for connecting the undercarriage drag strut caused that the material in this area withstood more than twice the number of load cycles established for this material. In order to determine the reasons for the increase in fatigue strength,...
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Fracture surface topography investigation and fatigue life assessment of notched austenitic steel specimens
PublicationThe objectives of this study were to investigate the fracture surface topography of X8CrNiS18-9 austenitic stainless-steel specimens for different loadings and notch radii and to supplement the knowledge about the fracture mechanisms for fatigue performance. Cases with three different values of the notch radius ρ and the stress amplitude σa were analysed. The fracture topographies were quantified by the areas over their entire...
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Laboratory fatigue assessment of large geocomposite-reinforced double-layered asphalt concrete beams
PublicationGeosynthetic reinforcement of asphalt layers has been used for several decades. Evaluation of the influence of these materials on pavement fatigue life is still ongoing, especially for new types of geocomposites. This paper presents the evaluation of fatigue performance of large asphalt concrete beams reinforced with a new type of composite in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions...
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Quasistatic and fatigue behavior of an AISI H13 steel obtained by additive manufacturing and conventional method
PublicationThis work aims to compare the mechanical behavior of an AISI H13 steel obtained by additive manufacturing with that obtained by conventional manufacturing methods. The average values of the ultimate tensile strength (UTS) and ductility obtained for the specimens produced by the conventional method were equal to 658 MPa and 18%, respectively, which compares with 503 MPa and 0.75% registered for the selective laser melting (SLM)...
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Fracture surface formation of notched 2017A-T4 aluminium alloy under bending fatigue
PublicationThe effect of cyclic loading on facture surface topology in notched components made by aluminium alloys is not completely clear. Fractogra-phy and fracture mechanics can help to understand this interdependency. This paper aims to study the distribution of the fracture surface roughness of notched 2017A-T4 aluminium alloy after bending fatigue using an optical focus-variation surface measurement technique by applying the fracture...
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Effect of bending-torsion on fracture and fatigue life for 18Ni300 steel specimens produced by SLM
PublicationIn this study, different fracture surfaces caused by fatigue failure were generated from 18Ni300 steel produced by selective laser melting (SLM). Hollow round bars with a transverse hole were tested under bending-torsion to investigate the crack initiation mechanisms and fatigue life. Next, the post-failure fracture surfaces were examined by optical profilometer and scanning electron microscope. The focus is placed on the relationship...
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The energy approach to fatigue crack growth of S355 steel welded specimens subjected to bending
PublicationThe study presents the results of the research on the rate of fatigue crack growth subjected to bending in the ferritic-pearlitic structure. The studies were carried out at a constant amplitude of the moment and at various values of the load ratios R and at the operating frequency of the machine of 28.4 Hz. Flat specimens made of S355 steel and with fillet welds and with double-sided blunt external notches as well as concave...
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Laboratory fatigue assessment of large geocomposite-reinforced double-layered asphalt concrete beams
PublicationGeosynthetic reinforcement of asphalt layers has been used for several decades. Evaluation of the influence of these materials on pavement fatigue life is still ongoing, especially for new types of geocomposites. This paper presents the evaluation of fatigue performance of large asphalt concrete beams reinforced with a new type of composite in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions...
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Influence of Heat Treatment Temperature on Fatigue Toughness in Medium-Carbon High-Strength Steels
PublicationCurrent research has demonstrated that the tempering temperature affects the martensitic transformation of medium-carbon high-strength steels. This temperature plays an important role in the final microstructure, percentage ratios of martensite to ferrite phases and, consequently, in the mechanical properties and the fatigue response. So far, the relationship between the martensitic tempering temperature and the cyclic deformation...
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Fatigue tests of steel Sandwich panel. Fifth International Conference on Marine Technology and Transportation.
PublicationW referacie przedstawiono wyniki badań laboratoryjnych paneli SANDWICH prowadzonych w Katedrze Technologii Okrętów, Systemów Jakości i Materiałoznawstwa Wydziału OiO na konstrukcjach w skali rzeczywistej. Dokonano porównania uzyskanych rezultatów w wynikami prezentowanymi w literaturze.
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Hydrogen-enhanced stress corrosion cracking and corrosion fatigue of HSLA steels in sea-water
PublicationPrzedstawiono ocenę podatności stali o wysokiej wytrzymałości na naprężeniowe pękanie korozyjne i zmęczenie korozyjne wspomagane przez wodór. Wykonano próby powolnego rozciągania i zmęczenia niskoczęstotliwościowego na stalach 17HMBVA i 14HNMBCu oraz ich złączach spawanych, w środowisku wody morskiej, przy polaryzacji katodowej. Zamieszczono wyniki badań elektrochemicznych oraz przełomów na skaningowym mikroskopie elektronowym.
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Fatigue ''safe-life'' criterion for metal elements under multiaxial constant and periodic loads.
PublicationRozpatrywane jest okresowe naprężenie którego kartezjańskie składowe są zadane w postaci szeregów Fouriera. Dla uwzględnienia naprężenia średniego wykorzystano uogólnioną formułę Soderberga dla materiałów ciągliwych. Zdefiniowano naprężenie równoważne o synchronicznych składowych i sformułowano kryterium zmęczenia, które obejmuje warunki zarówno wytrzymałości statycznej jak i bezpieczeństwa zmęczeniowego. Kryterium to zawiera stałe...
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Spectral criterion for high-cycle fatigue of metals under multiaxial static and stochastic loading.
PublicationPraca dotyczy oceny zmęczenia metali ciągliwych w złożonych stanach wieloosiowych obciążeń statycznych i dynamicznych, przy założeniu, że składowe naprężenia są stacjonarnymi procesami stochastycznymi, które są stacjonarnie skorelowane i różniczkowalne w sensie średniokwadratowym. Przyjmując, że wartości średnie i gęstości widmowe mocy tych procesów są znane, sformułowano kryterium ograniczonej trwałości zmęczeniowej w dziedzinie...
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Fatigue Performance of Double-Layered Asphalt Concrete Beams Reinforced with New Type of Geocomposites
PublicationThe reinforcement of asphalt layers with geosynthetics has been used for several decades, but proper evaluation of the influence of these materials on pavement fatigue life is still a challenging task. The presented study investigates a novel approach to the reinforcement of asphalt layers using a new type of geogrid composite, in which square or hexagonal polypropylene stiff monolithic paving grid with integral junctions is bonded...
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Consideration of Pseudo Strain Energy in Determination of Fatigue Life and Microdamage Healing of Asphalt Mastics
PublicationRest periods between cyclic loads can lead to recovery of damage and extension of fatigue life. This phenomenon is referred to as healing. Healing is clearly observed in bituminous materials, such as asphalt mastics, which belong to the components of asphalt mixtures. Due to the nature of road pavement traffic loading, which is characterized by series of intermittent pulses with rest periods, consideration of healing is necessary...
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Prediction of the fatigue lifetime of PUR structural elements using a combined experimental-numerical approach
PublicationThis paper presents a method for estimating the fatigue life of polyurethane elastomeric components. A rubber replacement - polyurethane of hardness 80ShA commonly used in vibration damping systems, for example, in motor vehicle suspensions, was used for the study. A metal-rubber bushing component was selected for analysis, and numerical analysis was carried out along with a fatigue model proposal based on a modification of the...
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Spectral criterion for high-cycle fatigue of anisotropic metals under multiaxial random loads
PublicationPraca dotyczy oceny ograniczonej trwałości zmęczeniowej metali ciągliwych, poddanych wieloosiowym obciążeniom statycznym i dynamicznym. Zakłada się, że kartezjańskie składowe tensora naprężenia są sumą losowych wartości średnich o znanych drugich momentach statystycznych i stacjonarnych procesów stochastycznych o znanych gęstościach widmowych mocy. Przyjmując, że procesy te są stacjonarnie skorelowane, różniczkowalne w sensie średnio-kwadratowym...
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Prediction of corrosion fatigue crack propagation life for welded joints under cathodic potentials
PublicationPrzy ochronie katodowej poniżej potencjału optymalnego obserwuje się przyspieszenie propagacji pęknięcia korozyjno-zmęczeniowego w porównaniu do konstrukcji nie chronionej. Zaproponowano własną formułę empiryczną na wpływ potencjału ochronnego na prędkość propagacji pęknięcia oraz własny wzór na [delta]K w złączu pachwinowym. Wyprowadzono wzór na krzywą ''S-Np'' (naprężenie - długość okresu propagacji pęknięcia). Zaprezentowana...
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Arm EMG Wavelet-Based Denoising System
PublicationThese paper presents research results of muscle EMG signal denoising. In the same time two muscles were examined - an adductor muscle (biceps brachii) and an abductor muscle (tricpeps brachii). The EMG signal was filtered using the wavelet transform technique, having selected the crucial parameters as: wavelet basis function (Daubechies 4), 10 th decomposition level, threshold selection algorithm (Heurestic) and a sln rescaling...
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Self-Organising map neural network in the analysis of electromyography data of muscles acting at temporomandibular joint.
PublicationThe temporomandibular joint (TMJ) is the joint that via muscle action and jaw motion allows for necessary physiological performances such as mastication. Whereas mandible translates and rotates [1]. Estimation of activity of muscles acting at the TMJ provides a knowledge of activation pattern solely of a specific patient that an electromyography (EMG) examination was carried out [2]. In this work, a Self-Organising Maps (SOMs)...
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Rapid method for the determination of organochlorine pesticides and PCBs in fish muscle samples by microwave-assisted extraction and analysis of extracts by GC-ECD
PublicationA procedure for the multiresidue determination of organochlorine pesticides and polychlorinated biphenyls in fish muscle samples has been developed. The method is based on the microwave-assisted extraction (MAE) of food samples from an acetonitrile-water (95 + 5, v/v) mixture followed by SPE cleanup of the extracts and analysis by GC with an electron capture detector. MAE operational parameters, such as the extraction solvent,...
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Muscle Cell Morphogenesis, Structure, Development and Differentiation Processes Are Significantly Regulated during Human Ovarian Granulosa Cells In Vitro Cultivation
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Influence of a Six-Week Swimming Training with Added Respiratory Dead Space on Respiratory Muscle Strength and Pulmonary Function in Recreational Swimmers
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Effect of exercise training on insulin sensitivity, mitochondria and computed tomography muscle attenuation in overweight women with and without polycystic ovary syndrome
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Post mortem development of meat quality as related to changes in cytoskeletal proteins of chicken muscles
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Mussel‐inspired biomaterials: From chemistry to clinic
PublicationAfter several billions of years, nature still makes decisions on its own to identify, develop, and direct the most effective material for phenomena/challenges faced. Likewise, and inspired by the nature, we learned how to take steps in developing new technologies and materials innovations. Wet and strong adhesion by Mytilidae mussels (among which Mytilus edulis—blue mussel and Mytilus californianus—California mussel are the most...
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Determination of Equivalent Axle Load Factors on the Basis of Fatigue Criteria for Flexible and Semi-Rigid Pavements
PublicationArtykuł przedstawia analizę współczynników równoważności obciążenia osi na podstawie kryteriów zmęczeniowych stosowanych w mechanistyczno-empirycznych metodach projektowania nawierzchni. Określono wzory służące do obliczania współczynnika w oparciu o szereg kryteriów zmęczeniowych. Podano wartości liczbowe współczynników.
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Damage assessment during creep and fatigue of power plant steels using destructive and nondestructive techniques
PublicationOpisano wyniki badń mających na celu ocena uszkodzeń od pełzania i zmęczenia stali energetycznych z wykorzystaniem technik niszczących i nieniszczących
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Experimental research on over-laminated steel sandwich panel connection to determine the form of fatigue failure
PublicationThe novel means of transport need to meet rising both the economic and ecologic requirements. In recent years the International Maritime Organization (IMO) introduced new measure of ship energy efficiency (the EEDI index), as well as new regulations regarding higher quality of fuel (so called Tier limits). It resulted in much higher interest of the technological development of ships. One of the solution having great potential is...
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Effect of selective laser treatment on initiation of fatigue crack in the main part of an undercarriage drag strut
PublicationThis paper presents the results of material characterization and a fatigue test conducted for a laser-re-melted drag strut used in an aircraft landing gear. The drag strut was re-melted with a CO2 laser beam. Eight re-melted paths were made in the form of spiral lines along the axis of the drag strut. Next, the drag strut was subjected to variable loads on a testing machine simulating loads occurring when an aircraft lands. The...
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The determination of deformations and stresses of laser welds used for fatigue assessment of steel sandwich panel joints
PublicationPanele typu sandwich znajdują szerokie zastosowanie w wielu gałęziach przemysłu. W przypadku niektórych zastosowań wymagających ocenę ryzyka dużą rolę odgrywa ocena trwałości zmęczeniowej spoin laserowych paneli. W pracy prezentowane są metody wyznaczania lokalnych odkształceń i naprężeń w połączeniach spawanych w celu oceny trwałości zmęczeniowej według hipotez lokalnych naprężeń i odkształceń.
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Relationship between Fatigue Condition of Asphalt Pavements and Deflection Lag from Traffic Speed Deflectometer
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Post-failure fracture surface analysis of notched steel specimens after bending-torsion fatigue
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Shot peening intensity effect on bending fatigue strength of S235, S355 and P460 structural steels
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The influence of type of dispersed phase on rolling contact fatigue of lubricating greases on mineral base oil
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Analysis of loading history influence on fatigue and fracture surface parameters using the method of induction trees
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Strain sequence effect on fatigue life and fracture surface topography of 7075-T651 aluminium alloy
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Compression and Fatigue Testing of High-Strength Thin Metal Sheets by Using an Anti-Buckling Device
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Scuffing and rolling contact fatigue resistance of discrete laser spot hardened austempered ductile iron
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Influence of laser processing of the low alloy medium carbon structural steel on the development of the fatigue crack
PublicationThe paper contains the results of the structural analysis, hardness tests and fatigue tests conducted for the medium carbon structural steel with low content of Cr and Ni after its processing with CO2 laser beam. Pre-cracks were made in the round compact tension (RCT) specimen used for fatigue test. Next, four paths, parallel to each other, were melted on both sides of the samples using a laser beam. The paths were perpendicular...
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On the use of uniaxial one-parameter damage laws for estimating fatigue life under multiaxial loading
PublicationThe goal of this paper is to evaluate the capabilities of different one-parameter fatigue laws to estimate crack initiation in notched components under multiaxial loading. Fatigue damage is accounted for through stress-based, strain-based, and energy-based approaches while the cyclic plasticity at the notch-controlled process zone is estimated using linear-elastic simulations. The results show that energy-based formulations established...
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Strain sequence effect on fatigue life and fracture surface topography of 7075-T651 aluminium alloy
PublicationThe paper studies the effect of strain-loading sequence on fatigue lifetime and fracture surface topographies in 7075-T651 aluminum alloy specimens. Fatigue tests were performed in two ways: (i) constant-amplitude loading and (ii) two series of variable amplitude loading with non-zero mean strain values. The topography of the fatigue fractures was measured over their entire surfaces with the help of an optical confocal measurement...
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Fatigue of titanium alloy Ti6Al4V with diamond structure obtained by Laser Power Bed Fusion method
PublicationThis paper presents the results of fatigue tests conducted on Ti6Al4V titanium alloy with diamond structure obtained by the Laser Power Bed Fusion method. Samples used in tests were printed with porosities: 81%, 73%, 50%, 34% and near-zero porosity. Samples were subjected to cyclic tests with a constant stress amplitude. The number of cycles until sample failure was registered. Obtained fatigue test results made it possible to...
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On the use of the cumulative strain energy density for fatigue life assessment in advanced high-strength steels
PublicationIn this paper, the applicability of the cumulative strain energy density is explored as a fatigue indicator parameter for advanced high-strength steels subjected to strain-controlled conditions. Firstly, the cyclic stress-strain responses of nine steels, selected from three multiphase families, encompassing different elemental compositions and different heat treatment routes, were studied. Then, the predictive capabilities of the...
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Fatigue life improvement using low transformation temperature weld material with measurement of residual stress
PublicationWelding processes often produce high levels of tensile residual stress. Low transformation temperature (LTT) welding wires utilise phase transformation strains to overcome the thermal contraction of a cooling weld. In this paper, the residual stress within each weld was quantified using the milling/strain gauge method, being the strain change measured as the weldment was milled away. The fatigue tests were conducted under uniaxial...
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Load path sensitivity and multiaxial fatigue life prediction of metals under non-proportional loadings
PublicationEngineering components often operate under complex loadings, in which the variable amplitude multiaxial stresses are raised by geometric discontinuities including holes, grooves, fillets and shoulders, etc. Besides, the non-proportional loading will lead to the rotation of maximum principal stress/strain and additional fatigue damage of structural elements in service. Consequently, the multiaxial and non-proportional loading have...
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Spectral criterion of infinite fatigue life of machinery parts under multi-axial random loading
PublicationPrzedstawiono kryterium nieograniczonej trwałości zmęczeniowej metalowych elementów poddanych wieloosiowym losowym drganiom. W celu jego wyznaczenia zastosowano hipotezę energii odkształcenia postaciowego i równanie Goodmana/Soderberga. Traktując gęstości widmowe mocy składowych naprężenia jako znane, kryterium to sformułowano w dziedzinie częstości. W przykładzie obliczeniowym rozpatrzono okresowy w sensie średniokwadratowym stan...
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Fatigue ''safe-life'' criterion for metal elements under multiaxial static and dynamic random loads.
PublicationRozpatrywane jest stacjonarne naprężenie, którego kartezjańskie składowe są zadane w postaci sumy losowej wartości średniej i procesu stochastycznego o znanych charakterystykach probabilistycznych. Dla uwzględnienia naprężenia średniego wykorzystano uogólnioną formułę Soderberga dla materiałów ciągliwych. Zdefiniowano naprężenie równoważne o okresowych (w sensie średniokwadratowym) składowych i sformułowano kryterium zmęczenia,...
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Roughness measurement results evaluation of 6082 aluminium alloy specimens after fatigue bending tests
PublicationIn this paper, the topography of 6082 aluminium alloy specimens after fatigue bending tests was studied with a comprehensive evaluation of measurement noise caused by vibration. Roughness results were acquired by contactless Focus Variation Microscopy (FVM). Studied data were pre-processed, removing the non-measured points and outliers with regular methods, respectively, and high-frequency noise was considered. The variations in...