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Search results for: failure
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Dynamics of mechanical model of implant-tissue system in ventral hernia repair
PublicationThe paper deals with a finite element modelling of implants in the problem of ventral hernia repair. The synthetic mesh implanted in the abdomen during surgery is here modelled as a membrane structure. Thesystem undergoes the internal abdominal pressure that occurs during the postoperative cough, the load identified in the literature as the main cause of the connection failure and hernia recurrence. The model can be used to estimate...
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Project Management Cycle in the Construction Industry Augmented by Collaborative Innovation Network Software
PublicationProject management is a very broad concept that has in recent times is growing rapidly. Management is especially complex in the construction sector, among the other sectors, due to the high uncertainty of workmanship and complexity of construction projects. Proper project management skills are an important factor in the success of projects, leading to reduced costs and shorten the time of investment. Nevertheless, most of the projects...
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Akaike's final prediction error criterion revisited
PublicationWhen local identification of a nonstationary ARX system is carried out, two important decisions must be taken. First, one should decide upon the number of estimated parameters, i.e., on the model order. Second, one should choose the appropriate estimation bandwidth, related to the (effective) number of input-output data samples that will be used for identification/ tracking purposes. Failure to make the right decisions results...
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The values of Permutation Entropy for individuals with Normal Sinus Rhythm
Open Research DataThe dataset consists of calculated values of entropy of 75 000 intervals between consecutive heartbeats (RR intervals) for 54 patients with normal sinus rhythm (NSR). The original data were taken from PhysioNet Normal Sinus Rhythm RR Interval Database (cf. Goldberger A., Amaral L., Glass L., Hausdorff J., Ivanov P.C., Mark R., Mietus J.E., Moody G.B.,...
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Automatic Correction of Non-Anechoic Antenna Measurements using Low-Pass Filters
PublicationPrototype measurements belong to key steps in the development of antenna structures. They are normally performed in expensive facilities, such as anechoic chambers (ACs). Alternatively, antenna performance can be extracted (at a low cost) in non-anechoic conditions upon appropriate post-processing. Unfortunately, existing correction algorithms are difficult to set up and prone to failure, which limits their practical usefulness....
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Flexural behaviour of concrete slabs reinforced with FRP bars in experiments and according to aci ACI 440.1R guide
PublicationThe paper presents research conducted on two concrete slabs reinforced with the carbon composite bars and two other concrete slabs reinforced with basalt composite bars. The carbon bars were plain, while the basalt ones were ribbed. The slabs were experimentally investigated in the flexural state of effort with the concentrated forces applied. The results are compared with the analytical solution proposed in the guide ACI 440.1R-06...
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Application of spectroscopy to the measurement of blood parameters
PublicationSpectroscopy is the study of formation and interpretation of the spectra arising from the interactions of all types of radiation on matter, understood as a collection of atoms and molecules. This is a very important department of optics which gives us many opportunities to measure various parameters such as material blood parameters. Among the diseases that are associated significantly with changes in rheological properties of...
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Effect of Thermal Shock During Legionella Bacteria Removal on the Corrosion Properties of Zinc-Coated Steel Pipes
PublicationThe purpose of this investigation was to conduct the failure analysis of a water-supply system made from zinc-coated steel. The observed corrosion process had an intense and complex character. The brownish deposits and perforations were present after 2-3 years of exploitation. The electrochemical study based on the Tafel polarization, corrosion potential monitoring, and electrochemical impedance spectroscopy together with microscopic...
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Markov Model of Disease Development and Recovery
PublicationMarkov models are commonly used to simulate diseases and allow modeling of multiple health states and outcomes. Starting with the well known Le Bras multistate model (cascading failure model) with time-independent transitions we will see how simple Markov mortality models may be pressed into the service of survival and event history analysis. We will focus on more complex models which will be able to take into account remission,...
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Modeling, simulation, and validation of a TB41 crash test of the H2/W5/B concrete vehicle restraint system
PublicationThe paper addresses numerical simulations of a concrete vehicle restraint system. The model is described in detail. The advanced material law of the continuous surface cap model was used to analyze the damage locations in concrete barrier segments. The results were validated against the TB41 full-scale crash test. The test was conducted in compliance with European standard EN 1317, and the validation was performed in accordance...
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Pedestrian and bicycle bridges as examples of safe collision-free road crossings
PublicationPedestrians are most at risk when they are crossing the road. This represents a significant proportion of all fatalities among pedestrians, amounting respectively to 50% in non-built-up areas and 75% in built-up areas. The most frequent reason for this accident is failure to give way. What is most terrible is that 30% of pedestrian accidents occurred at marked pedestrian crossings. Therefore, an important part of pedestrian safety...
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Numerical analysis of lumbar spine injury during road safety barrier collision
PublicationPurpose: Enhancing road safety is a critical goal worldwide, necessitating the development of clear standards for road safety systems. This study focuses on lumbar spine (L-spine) compression injuries during collisions with concrete road safety barriers (RSBs). It aims to analyze internal forces during impact to understand L-spine injury biomechanics in such accidents. Methods: The research included a literature review, analyzing...
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Microcracking monitoring and damage detection of graphene nanoplatelets-cement composites based on acoustic emission technology
PublicationThis study aims to identify the micro-cracking pattern and structural applications of cement composites replaced with 0 wt%, 0.04 wt%, and 0.08 wt% contents of graphene nanoplatelets (GNPs) over cement weight through acoustic emission (AE) monitoring under mechanical degradation. The ultraviolet-visible spectroscopy (UV–vis) results showed that at 60 min sonication period, GNP-4 showed maximum absorbance rate of 16.15% compared...
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Micro-cracking pattern recognition of hybrid CNTs/GNPs cement pastes under three-point bending loading using acoustic emission technique
PublicationThe generation of microcracks has an important influence on the behaviour of concrete structures. In this study, the acoustic emission (AE) technique was used to investigate the fracture phenomena and micro-cracking behavior of hybrid carbon nanotubes (CNTs, the 1-D allotrope of carbon atoms) and graphene nanoplatelets (GNPs, 2D monolayer of sp2-hybridized carbon atoms), cement composites under three-point bending loading. In...
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Why do Open Government Data initiatives fail in developing countries? A root cause analysis of the most prevalent barriers and problems
PublicationOpen government data (OGD) include the provision of government data, which have so far been reserved for the provision of public utilities and services, wherein different stakeholders may create value out of the same source. Recently, OGD initiatives around the world have dampened or were found to be inadequate for one or other reasons. The present study seeks to underline the root causes behind these inadequate or stalled initiatives...
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Activated Tungsten Inert Gas Weld Characteristics of P91 Joint for Advanced Ultra Supercritical Power Plant Applications
PublicationActivated Tungsten Inert Gas (A-TIG) welding, a variant of tungsten inert gas (TIG) welding, was used for welding P91. In Generation IV power plants, P91 welds are prone to premature failure due to the presence and formation of brittle phases and creep at high temperatures. When performing A-TIG welding, the flux composition plays a role in the reversal of the Marangoni flow in the weld pool, which ultimately determines the level...
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Upoważnienie do zaciągania zobowiązań na rzecz jednostek samorządu terytorialnego jako naruszenie dyscypliny finansów publicznych
PublicationArtykuł poświęcony jest zagadnieniu upoważnienia do zaciągania zobowiązań na rzecz jednostek samorządu terytorialnego. W teoretycznej części zdefiniowano dwa pojęcia: zobowiązań oraz zaciągania zobowiązań. Następnie scharakteryzowano zagadnienie podmiotowego i przedmiotowego zaciągania zobowiązań. Nieprzestrzeganie przepisów dotyczących zaciągania zobowiązań, które zawarte są głównie w ustawie o finansach publicznych, prowadzi...
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Numerical Model of the Aortic Valve Implanted Within Real Human Aorta
PublicationCardiovascular system diseases are the main cause of deaths in developed and developing countries. The main reasons are myocardial infarction, heart failure, stroke and valvular diseases. These are caused mainly by arteriosclerosis. The valvular diseases involve a significant burden for the health care system and their frequency is rising with the patient age. This work describes the tools and numerical models appropriate for modeling...
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Experimental Investigation of the Performance of an Innovative Implantable Left Ventricular Assist Device—Proof of Concept
PublicationThis paper presents the results of experimental performance of an innovative left ventricular assist device working on a specially designed test stand. The introduced invention is mainly applied for supporting the heart in patients with end-stage heart failure accompanied by mitral valve regurgitation and pulmonary hypertension. Moreover, the developed device has the form of a flexible balloon forming an intracardiac inert gas-filled...
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Polynomial Algorithm for Minimal (1,2)-Dominating Set in Networks
PublicationDominating sets find application in a variety of networks. A subset of nodes D is a (1,2)-dominating set in a graph G=(V,E) if every node not in D is adjacent to a node in D and is also at most a distance of 2 to another node from D. In networks, (1,2)-dominating sets have a higher fault tolerance and provide a higher reliability of services in case of failure. However, finding such the smallest set is NP-hard. In this paper, we...
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Probabilistic sensitivity of limit states of structures : The Monte Carlo simulation
PublicationThe main issue of the paper is the probabilistic sensitivity of the limit states of structures with respect to selected input design variables. Attempt to the problem is done by the dedicated Monte Carlo simulation procedure. Basic design variables are random variables of given probability distributions, presented in the form of random numbers. Uni-parametrical increment of the dominant basic variable (basic variables) is done,...
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Monitoring of CRT by means of impedance multiple measurements - simulation studies
PublicationCardiac resynchronization therapy (CRT) is a very promising treatment for patients with congestive heart failure. An Impedance Cardiography (ICG) is used for evaluation of heart mechanical activity. A simulation study with the use of a FEM model was performed. The developed realistic model of the thorax, based on CT data obtained from examination of a 68-year-old man, consisted of 212 000 tetrahedral elements. Different configurations...
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Response of a steel tank during earthquakes and mining tremors - experimental investigation
PublicationCylindrical steel tanks are very popular shell structures used to store the products of chemical and petroleum industries. Any failure might have disastrous consequences, therefore their safety and reliability is essential. Earthquakes are the most dangerous and also the most unpredictable dynamic loads acting on such structures. On the other hand, mining tremors are usually considered to be less severe due to lower acceleration...
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Traffic-induced vibrations. The impact on buildings and people
PublicationTraffic-induced vibrations have recently been of major concern to engineers as one of the aspects of so called physical environmental pollution. The interest is related to the observations of serious negative effects of such kind of vibrations on buildings and their inhabitants. Traffic-induced vibrations may cause plaster cracks, structural damage and even failure and collapse of the structure. They may also be the reason of serious...
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The impact of material degradation on the resistance and reliability of truss structures
PublicationThe paper analyses limit load-carrying capacity and buckling load of truss towers used to support high voltage power lines. The analysed typical structure was subjected to characteristic loads and their combinations. The results were applied to assess structural resistance with regard to steel corrosion in the long-term operation. The extent of structural deterioration was assessed due to Young's modulus decrement in the course...
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APPLICATION OF INFRARED THERMOGRAPHY TO NON-CONTACT TESTING OF AD/DC POWER SUPPLY
PublicationTesting of AC/DC power supplies using the thermography was carried out in order to assess their assembly and operation correctness before launching them on the market. The investigation was carried out for 17 AC/DC power supplies which passed the standard tests (measurements of their basic parameters and characteristics). The investigation consisted of two steps. In the first step the dispersion of temperature on power supply boards...
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Viscoplastic damage analysis of structures subjected to impact loading. Plate and shell structures. - Ł. Pyrzowski.
PublicationThe work presents the investigation in the response of plate-shell structures subjected to impact loading (gas mixture explosions). This phenomenon is studied in the context of its mechanical aspects, mainly the ductile fracture prediction. The work starts with the literature review and the description of theories, which are nowadays the most popular in the damage and failure modelling. After selecting the theoretical models and...
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Asynchronous WAM with Irregular Pulse Repetition
PublicationRadiolocation systems for aviation based on Multi-Lateration (MLAT) typically use a set of synchronised ground sensors to receive radio signals broadcast by onboard transmitters. In most cases, the sensor synchronisation in Wide Area Multi-Lateration Systems (WAM) is provided by Global Navigation Satellite System (GNSS) receivers. However, in the case of synchronisation failure, there is still a possibility to estimate the coordinates...
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Local and global response of sandwich beams made of GFRP facings and PET foam core in three point bending test
PublicationIn the paper behaviour of laminated sandwich beams (FRP face sheet – PET foam core – FRP face sheet) subjected to three point bending is studied. The paper aim is to find practical descriptions enabling effective and accurate estimation of the elastic response, damage and failure of the beams, basing on experiments and static calculations. Therefore a number of tests are described, that were done on laminated coupons and foam specimens...
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A Survey Investigating the Influence of Business Analysis Techniques on Software Quality Characteristics
PublicationBusiness analysis is recognized as one of the most important areas determining the outcome (success or failure) of a software project. In this paper we explore this subject further by investigating the potential impact of techniques applied in business analysis on essential software quality characteristics. We conducted a literature search for software quality models, analyzed the existing models and selected a subset of commonly...
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The values of Block Entropy for individuals with Normal Sinus Rhythm
Open Research DataThe dataset consists of calculated values of entropy of 75 000 intervals between consecutive heartbeats (RR intervals) for 54 patients with normal sinus rhythm (NSR). The original data were taken from PhysioNet Normal Sinus Rhythm RR Interval Database (cf. Goldberger A., Amaral L., Glass L., Hausdorff J., Ivanov P.C., Mark R., Mietus J.E., Moody G.B.,...
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Tensile test results of fused filamend fabricated polylactyde and polylactyde with carbon fiber filler
Open Research DataThe Dataset contains the results of the mechanical behaviour of dog-bone shaped specimens. The specimens were additively manufactured with the fused filament fabrication (FFF) method. They used two different materials polylactide (PURE PLA) and polylactide with carbon fibre filler (PLA+CF). The specimens were segregated into three groups - unsterilized,...
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The Smith-Watson-Topper parameter and fracture surface topography relationship for additively manufactured 18Ni300 steel subjected to uniaxial variable-amplitude loading
PublicationIn this paper, the association between Smith-Watson-Topper (SWT) parameter and fracture surface topography is studied in additively manufactured maraging steel exposed to variable-amplitude fatigue loading. The post-failure fracture surfaces were examined using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focal point is on the correspondence between fatigue characteristics, articulate...
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Wavelet transform analysis reveals differences between patients with impaired LVEF and healthy individuals
PublicationHeart failure (HF) is a global pandemic. It af- fects 64 million people worldwide, with stead- ily increasing incidence, morbidity, mortality, and economic burden [1]. Forecasts indicate continued rising prevalence, especially among the elderly and in low-to-middle socio-de- mographic index regions [2]. Left ventricular ejection fraction (LVEF) significantly impacts HF treatment and prognosis [3]. The sequence of physiological...
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Technique for reducing erosion in large-scale circulating fluidized bed units
PublicationThis paper presents a methodology, implemented for a real industrial-scale circulating fluidized bed boiler, to mitigate the risk of heating surfaces exposed to an intensive particle erosion process. For this purpose, a machine learning algorithm was developed to support the boiler reliability management process. Having a tool that can help mitigate the risk of uncontrolled power unit failure without expensive and technically complex...
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Effect of austempering temperature on microstructure and cyclic deformation behaviour of multiphase low-carbon steel
PublicationThis paper examined the cyclic deformation behaviour of multiphase low-carbon steel that was subjected to austempering heat treatments at four temperatures (190 °C, 230 °C, 275 °C, and 315 °C) below the martensite start temperature (Ms = 353 °C). The tests were conducted at room temperature, under fully reversed strain-controlled conditions, with strain amplitudes in the range 0.5–1.0%. The microstructure was observed by transmission...
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The influence of pressure drop on the working volume of a hydraulic motor
PublicationReliability and maintenance analysis of hydraulic positive machines basicly focused on the processes of their wear and failure. But in order to correctly assess the mechanical and volumetric efficiency of a hydraulic motor, both at the stage of development research or at the stage of control tests during its exploitation, the working volume of this motor must be correctly determined. Therefore this paper proposes a new method of...
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Experiments and calibration of a bond-slip relation and efficiency factors for textile reinforcement in concrete
PublicationTextile reinforcement yarns consist of many filaments, which can slip relative each other. At modelling of the global structural behaviour, interfilament slip in the yarns, and slip between the yarns and the concrete can be considered by efficiency factors for the stiffness and strength of the yarns, and by applying a bond-slip relation between yarns and concrete. In this work, an effective and robust method for calibration of...
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Influence of operating pressure on the durability of a satellite hydraulic motor supplied by rapeseed oil
PublicationThis article describes the results of a durability test of a hydraulic satellite motor supplied by rapeseed oil. The tests were carried out on a test stand in a power recuperation system. The tests of the motor were carried out at a constant shaft speed for three fixed pressure drops in the motor. This made it possible to demonstrate the influence of the motor operating pressure on the durability of the satellite mechanism. The...
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The efficiency of bankruptcy proceedings and the severity of insolvency regulations in view of the implementation of the New Opportunity Policy
PublicationThe article investigates the relationship between the efficiency of insolvency proceedings, as measured by their duration, and measures the severity of bankruptcy law toward debtors in 27 countries, of which 23 are EU. This objective was achieved using quantitative methods – Pearson’s correlation, pooled panel regression and Granger causality. Research shows no direct correlation between the two variables mentioned above. The increase...
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Experimental study on steel columns subjected to impact load under earthquake conditions
PublicationEarthquakes affecting urbanized regions cause exceptional loads to load bearing structural elements such as columns. Such a boost in the load conditions can lead to severe damages which, in a worst case scenario, can lead to a total collapse of a building. This boost is caused by the horizontal ground movement generating a rise in the internal forces due to considerable large displacement between the top and bottom support of columns....
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Protection in elastic optical networks
PublicationIn this article, we analyze gains resulting from the use of EON architectures with special focus on transportation of cloud-ready and content-oriented traffic in the context of network resilience. EONs are a promising approach for future optical transport networks and, apart from improving the network spectral efficiency, bring such new capabilities as squeezed protection, which reduces resource requirements in failure scenarios....
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Rural Landscape Planning for Sustainable Development. The Case of Poland
PublicationThis text results from theoretical study on the possibilities of rural landscape renovation in Poland. The introduction marks new spatial phenomena and the scope of their influence. It indicates social and cultural reasons of the changes, and states the need of their renewed interpretation. The second part of the article contains a description of the degrading cultural landscape of the country and presents its features. It then...
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Flexural behavior of composite structural insulated panels with magnesium oxide board facings
PublicationThe current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include...
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Design of dimensionally stable composites using efficient global optimization method
PublicationDimensionally stable material design is an important issue for space structures such as space laser communication systems, telescopes, and satellites. Suitably designed composite materials for this purpose can meet the functional and structural requirements. In this paper, it is aimed to design the dimensionally stable laminated composites by using efficient global optimization method. For this purpose, the composite plate optimization...
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On instabilities and post-buckling of piezomagnetic and flexomagnetic nanostructures
PublicationWe focus on the mechanical strength of piezomagnetic beam-like nanosize sensors during post-buckling. An effective flexomagnetic property is also taken into account. The modelled sensor is selected to be a Euler-Bernoulli type beam. Long-range interactions between atoms result in a mathematical model based on the nonlocal strain gradient elasticity approach (NSGT). Due to possible large deformations within a post-buckling phenomenon,...
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Natural Products Counteracting Cardiotoxicity during Cancer Chemotherapy: The Special Case of Doxorubicin, a Comprehensive Review
PublicationCardiotoxicity is a frequent undesirable phenomenon observed during oncological treatment that limits the therapeutic dose of antitumor drugs and thus may decrease the effec-‐‑ tiveness of cancer eradication. Almost all antitumor drugs exhibit toxic properties towards cardiac muscle. One of the underlying causes of cardiotoxicity is stimulation of oxidative...
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Fractal dimension for bending–torsion fatigue fracture characterisation
PublicationFracture surfaces after biaxial fatigue tests were compared using fractal dimension for three types of metallic materials in smooth and notched specimens made of S355J2 and 10HNAP steels and 2017-T4 aluminium alloy, considering both proportional and nonproportional cyclic loading. High-resolution optical 3D measurement studies were performed on the entire fracture surface. A direct correlation between fractal dimension and fatigue...
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Monitoring Steel Bolted Joints during a Monotonic Tensile Test Using Linear and Nonlinear Lamb Wave Methods: A Feasibility Study
PublicationThe structural integrity of steel bolted joints may be compromised due to excessive loading. Therefore, condition assessment and the detection of potential defects before they cause a failure have become a major issue. The paper is focused on the condition monitoring of a bolted lap joint subjected to progressive degradation in a tensile test. The inspection used Lamb waves propagated through the overlap area. Wave propagation...
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2-D constitutive equations for orthotropic Cosserat type laminated shells in finite element analysis
PublicationWe propose 2-D Cosserat type orthotropic constitutive equations for laminated shells for the purpose of initial failure estimation in a laminate layer. We use nonlinear 6-parameter shell theory with asymmetric membrane strain measures and Cosserat kinematics as the framework. This theory is specially dedicated to the analysis of irregular shells, inter alia, with orthogonal intersections, since it takes into account the drilling...