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Littérature scientifique sur le sujet « Equivalent fatigue load method »

Auteur : Grafiati

Publié le 27 avril 2023

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Articles de revues sur le sujet "Equivalent fatigue load method"

Gao, Ruofan, et Jie Li. « Equivalent constant-amplitude fatigue load method based on the energy equivalence principle ». Advances in Structural Engineering 22, n^o 13 (5 juin 2019) : 2892–906. http://dx.doi.org/10.1177/1369433219852705.

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An equivalent constant-amplitude cyclic loading method for random vehicle load is proposed based on the concept of energy equivalence. The filtered compound Poisson process is adopted to describe random vehicle load, through which the vehicle load spectrum is gained. The total dissipated energy due to fatigue loads subjected to concrete structures is deduced by introducing a multi-scale model, in which the energy dissipation induced by the nano-cracks level is presented, and the energy transition from nano to macro scales is derived. By assuming that the total energy dissipation under random loading equals that under equivalent constant-amplitude loading, the equivalent load ratio and amplitude as well as the number of equivalent cycles for random vehicle load are obtained. To validate the effectiveness of the proposed method, a set of numerical simulations is presented. The fatigue damage accumulations for concrete structures under both the random load and the equivalent loads converted by the proposed method and the classic root mean square method are calculated. By comparing with the root mean square method, the accuracy and advantage of the proposed equivalent load model are verified.

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Zuo, Huang, Yue Chun Zhang, Ping Liu, Wen Wang et Shun Xiong. « Study on Loads of Accelerated Contact Fatigue Testing and its Application ». Applied Mechanics and Materials 86 (août 2011) : 680–83. http://dx.doi.org/10.4028/www.scientific.net/amm.86.680.

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For reducing the development time and cost, determining the load of accelerated contact fatigue testing of a multi-case and multi-stage drive train, multilevel design load method was used to calculate the pitting equivalent loads of gears according to the load spectrum. A reasonable load of pitting fatigue testing was determined after analyzing and studying the pitting equivalent loads of gears. Based on a reducer used for a cement mixer, the pitting equivalent loads of gears were calculated, and the load of pitting fatigue testing was determined. The damage ratios of gears were calculated by the pitting equivalent loads of gears and the testing load, separately, using software MASTA. The results from the load of pitting fatigue testing and the testing load were coincident.

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Ligaj, Bogdan, et Robert Sołtysiak. « Problems of Equivalent Load Amplitude in Fatigue Life Calculations ». Polish Maritime Research 23, n^o 1 (1 janvier 2016) : 85–92. http://dx.doi.org/10.1515/pomr-2016-0012.

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Abstract This paper presents issues of fatigue life calculations in operational load conditions. The assumed runs were so processed as to get a set of sinusoidal cycles by using the following methods: full cycles counting method and rainflow counting method. On the basis of such sets of cycles of the varying parameters Sm i and Sa i were prepared block load spectra of equivalent amplitudes Saz , obtained with the use of an original method of these authors, in which two-parameter fatigue characteristics were applied. The work resulted in comparison of fatigue life results for load spectra determined by using the assumed cycles counting methods and the assumed two-parameter fatigue characteristics: the model IM, model II, model III and model IV, respectively.

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Xu, Ge Ning, Xiao Ning Fan, Feng Yi Lu et Rui Gang Yang. « The ANN Method of Obtaining Fatigue Load Spectrum of Overhead Traveling Crane ». Applied Mechanics and Materials 20-23 (janvier 2010) : 525–31. http://dx.doi.org/10.4028/www.scientific.net/amm.20-23.525.

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For the realization of remaining fatigue life estimation, prevention of catastrophic accidents and safety of the cranes in service, it is necessary to obtain the actual load spectrum of overhead traveling crane. Due to the limitation of condition in field experiment, it is difficult to implement a large number of actual Load Spectrum experiments. So, the present paper will focus on overhead traveling cranes for general purpose and conduct data investigation. In a certain period，the numbers of work cycles corresponding to different lifting loads for different rated lifting capacity are collected. Based on Levenberg-Marquardt Back Propagation(LMBP) Artificial Neural Network(ANN), the equivalent load spectrum, which is equivalent to the actual load spectrum, is acquired. The example demonstrates: It is feasible to establish the equivalent load spectrum for some types of crane using ANN. Meanwhile, the equivalent load spectrums of the typical cranes in this type could be obtained and predicted through the trained network. It has provided the reliable data for the reliability analysis and fatigue life estimation of the crane. In the approach to establish the crane load spectrum, an exploring and initiating study work have been done.

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Zhu, Hong Bing. « Calculation Methods for Equivalent Fatigue Stress Amplitude Based on Corten-Dolan Accumulative Damage Rule ». Advanced Materials Research 156-157 (octobre 2010) : 1271–74. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.1271.

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Structures often enduring random amplitude load or multilevel amplitude load. However, the test researches on fatigue often using equivalent amplitude load. It is very important for fatigue research that how to accurately evaluate structure’s fatigue properties of random amplitude load or multilevel amplitude load when only using equivalent amplitude load fatigue test results. According to damaging degree equivalent principle of multilevel amplitude load or random amplitude load, deduced equivalent stress amplitude calculation formula using linearity Miner accumulative damage rule and Corten-Dolan accumulative damage rule. Introduced the formula’s using method on fatigue detail or fatigue life evaluation. Utilizing the S-N curve and S-N equation from RC beams fatigue experiment, verified the formula aiming at 3 RC beams’ random amplitude fatigue experiment results, and it is indicated that the formula’s results had quite high precision and approached the experimentation result though it is partial security. The formula operated convenience and it had higher precision compared to similar formula, so the formula suit for engineering application.

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Miao, Yizhi, Mohsen N. Soltani et Amin Hajizadeh. « A Machine Learning Method for Modeling Wind Farm Fatigue Load ». Applied Sciences 12, n^o 15 (22 juillet 2022) : 7392. http://dx.doi.org/10.3390/app12157392.

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Wake steering control can significantly improve the overall power production of wind farms. However, it also increases fatigue damage on downstream wind turbines. Therefore, optimizing fatigue loads in wake steering control has become a hot research topic. Accurately predicting farm fatigue loads has always been challenging. The current interpolation method for farm-level fatigue loads estimation is also known as the look-up table (LUT) method. However, the LUT method is less accurate because it is challenging to map the highly nonlinear characteristics of fatigue load. This paper proposes a machine-learning algorithm based on the Gaussian process (GP) to predict the farmlevel fatigue load under yaw misalignment. Firstly, a series of simulations with yaw misalignment were designed to obtain the original load data, which considered the wake interaction between turbines. Secondly, the rainflow counting and Palmgren miner rules were introduced to transfer the original load to damage equivalent load. Finally, the GP model trained by inputs and outputs predicts the fatigue load. GP has more accurate predictions because it is suitable for mapping the nonlinear between fatigue load and yaw misalignment. The case study shows that compared to LUT, the accuracy of GP improves by 17% (RMSE) and 0.6% (MAE) at the blade root edgewise moment and 51.87% (RMSE) and 1.78% (MAE) at the blade root flapwise moment.

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Natarajan, Anand. « Damage equivalent load synthesis and stochastic extrapolation for fatigue life validation ». Wind Energy Science 7, n^o 3 (2 juin 2022) : 1171–81. http://dx.doi.org/10.5194/wes-7-1171-2022.

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Abstract. Present verification of the fatigue life margins on wind turbine structures utilizes damage equivalent load (DEL) computations over a limited time duration. In this article, a procedure to determine long-term fatigue damage and remaining life is presented as a combination of stochastic extrapolation of the 10 min DEL to determine its probability of exceedance and computationally fast synthesis of DELs using level crossings of a Gaussian process. Both the synthesis of DELs and long-term stochastic extrapolation are validated using measured loads from a wind farm. The extrapolation for the blade root flap and tower base fore–aft damage equivalent moment is presented using a three-parameter Weibull distribution, whereby the long-term damage equivalent load levels are forecast for both simulated and measured values. The damage equivalent load magnitude at a selected target probability of exceedance provides an indicator of the integrity of the structure for the next year. The extrapolated damage equivalent load over a year is validated using measured multi-year damage equivalent loads from a turbine in the Lillgrund wind farm, which is subject to wakes. The simulation of damage equivalent loads using the method of level crossings of a Gaussian process is shown to be able to reconstruct the damage equivalent load for both blade root and tower base moments. The prediction of the tower base fore–aft DEL is demonstrated to be feasible when using the Vanmarcke correction for very narrow band processes. The combined method of fast damage equivalent load computations and stochastic extrapolation to the next year allows a quick and accurate forecasting of structural integrity of operational wind turbines.

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Jung, Dong Soo, Hyoung Eui Kim, Sung Hun Kim et E. Sok Kang. « Development of Accelerated Life Test Method of Hydraulic Pump ». Key Engineering Materials 326-328 (décembre 2006) : 1861–64. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1861.

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This paper proposes a new accelerated life test method of hydraulic pump used in vehicles, which have multiple alternating loads. For determination of life time of hydraulic pump for given field conditions with respect to duty cycle, the equivalent load and speed of this unit has to be determined. Equivalent load and speed can be calculated from the given duty cycle using the predominant theory for cumulative fatigue damage. Finally, we can perform accelerated life test on hydraulic pump by determination of test pressure and speed from calculated equivalent cumulative damage per working cycle and weighted average speed.

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Zhao, Min, et Jin Di. « Fatigue Load for Cable-Girder Anchorage Structure of Highway and Light-Railway Cable Stayed Bridge ». Advanced Materials Research 838-841 (novembre 2013) : 1028–33. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.1028.

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Because fatigue load of bridge structure under the highway and light-railway loads has not been specified in current design codes, it is necessary to study the fatigue load of cable-girder anchorage structure of the highway and light-railway cable stayed bridge. Take Chongqin Hongyan Jialing River bridge as the subject of investigation, the fatigue load of cable-girder anchorage structure is computed through MatLab program developed by Monte Carlo method and the rain flow method. According to the traffic flow surveys on the load spectrum, the fatigue load of cable-girder anchorage structure was calculated accurately by the MatLab program. Through comparison with the calculation results of the MatLab program, a fatigue load calculation method used equivalent fatigue vehicle based on the Palmgren-Miner linear cumulative damage theory is reliable and accurate.

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Wang, Lei, Fa Ming Wu, Xing Mei Lv et Dian Wang. « A Fatigue Analysis Method Research for Main Frame of the Large-Scale Wind Turbine ». Applied Mechanics and Materials 226-228 (novembre 2012) : 995–99. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.995.

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This paper presents a method to calculate the main frame damage of fatigue directly by the equivalent fatigue load of the wind turbine. This method can take advantage of the equivalent fatigue load to check the damage of the main frame fast. This paper also analyses the weight of each components of the fatigue load, which is convenient for the optimization design of the structure for main frame. Comparing this method with traditional fatigue calculation method, we can find this method is reasonable and veracious. Using this method can greatly improve the efficiency of the damage estimate for the main frame. It can be analogized to other mechanical components, and this method is very valuable in practical engineering applications.

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Thèses sur le sujet "Equivalent fatigue load method"

Prinsloo, Etienne Pieter Willem. « Fatigue equivalent static load : Methodology for the design of vehicle structures ». Diss., University of Pretoria, 2003. http://hdl.handle.net/2263/25966.

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This study is concerned with the design of vehicle structures through the use of Fatigue Equivalent Static Loads (FESL). A large percentage of failures of mechanical structures can be attributed to fatigue. Furthermore, it is also generally accepted that defective structural design is mostly caused by insufficient knowledge of the input loading. The fatigue loads experienced by vehicle structures are especially difficult to quantify. In the current competitive markets, it is essential to use a pro-active, timely and cost effective process to solve fatigue related problems. The heart of the FESL methodology is the ability to condense a large amount of input load data into a single fatigue load. This is achieved by calculating the damage of the measurements and converting it to an equivalent stress, through the use of a calibration matrix obtained from a unit-load finite element analysis. A Fatigue Equivalent Static Load can now be determined, and the vehicle structure can be evaluated for durability.
Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2003.
Mechanical and Aeronautical Engineering
unrestricted

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Warneboldt, Iona. « Multiaxial fatigue design of elastomeric parts using Equivalent Fatigue Loads ». Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0002.

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Trois étapes sont mises en oeuvre ici : la méthode de localisation, la fonction de dommage matériau et le processus de détermination des chargements équivalents en fatigue (CEF). De nombreux essais de fatigue ont été réalisés (415 au total) pour étudier le comportement en fatigue sous chargement multiaxial relaxant et non relaxant sur des éprouvettes de caoutchouc naturel. La durée de vie et les caractéristiques des fissures sont analysées pour finalement introduire un critère de fatigue approprié basé sur le plan critique et permettant de rendre compte de l'effet de déformation moyenne. Ce critère est généralisé à travers une méthode originale de recherche du plan critique. Pour estimer la réponse mécanique locale (méthode de localisation), une méthode de couplage des axes adaptée à la nature non linéaire des structures élastomères est proposée. Elle est basée sur la décomposition multiplicative des tenseurs du gradient de la déformation. Ces deux étapes sont ensuite mises en oeuvre dans le cadre du processus de détermination du CEF. Pour cela, une méthode d'optimisation globale est ajoutée pour déterminer les chargements simplifiés, induisant partout localement le même endommagement en fatigue dans la structure étudiée que le RLD. Le temps de calcul de cette optimisation est réduit en ne considérant qu'un sous-ensemble de points matériels, les plus endommagés, pour la détermination du CEF. Enfin, la méthode a été testée sur une éprouvette afin de souligner ses capacités et de valider l'approche
This thesis introduces an Equivalent Fatigue Load (EFL) approach for the multiaxial fatigue design of elastomeric parts. As direct Finite Element Analysis (FEA) calculations of automotive in-service loads (Road Load Data (RLD)) are too expensive, the objective is to derive simplified load blocks as a realistic input for numerical damage calculations. Three streps are applied for this method: the localization method, the material damage function and the EFL determination process. Various fatigue tests have been conducted (415 samples) to study the fatigue behavior of this complex type of relaxing and non-relaxing multiaxial loading on natural rubber specimens. Lifetime and crack features are analyzed to eventually introduce an appropriate critical planebased fatigue measure and to establish a novel mean strain effect model. This criterion is generalized throughout an original critical plane search method. To estimate the local mechanical response (localization method), this thesis identifies an axes-coupling method that is fitted for the nonlinear nature of elastomeric structures. It is based on the multiplicative decomposition of the deformation gradient tensors. These two steps are then implemented in the framework of the EFLdetermination process. For this, a global optimization method is added to determine the simplified load blocks, causing locally the same fatigue behavior in the given structure. The computational costs of this optimization are reduced by only considering a subset of the most damaged material points for EFLdetermination. Finally, the method has been challenged on a specimen to outline its capabilities and to validate the approach

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Rinehart, Adam James. « Effects of localized geometric imperfections on the stress behavior of pressurized cylindrical shells ». Texas A&M University, 2003. http://hdl.handle.net/1969/37.

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SANTOS, RODRIGO BIANCHI. « PARAMETRIC OPTIMIZATION OF TRUSS STRUCTURES UNDER DYNAMIC LOADING USING THE EQUIVALENT STATIC LOAD METHOD ». PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35802@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Otimização estrutural sujeita a carregamentos dinâmicos é um problema desafiador em vários aspectos, a começar pelo grande número de restrições que devem ser atendidas em todos os instantes de tempo. Além disso, o custo computacional para avaliar os gradientes destas restrições é bastante elevado e requer um grande espaço de armazenamento. Na literatura, alguns métodos reduzem o número de restrições avaliando em instantes de tempo selecionados, como o pior caso por exemplo, ou ainda constroem um funcional equivalente, integrando as restrições violadas ao longo do tempo, assim eliminando essa dependência. Nesta dissertação, o método do Carregamento Estático Equivalente (ESL) é utilizado, no qual o problema dinâmico original é transformado em uma sequência de subproblemas de otimização linear estática com múltiplos casos de carga. Um atrativo deste método é a possibilidade da solução de problemas não lineares, evitando o alto custo devido às repetidas análises estruturais e cálculos das restrições. Problemas clássicos de treliças planas submetidas a carregamentos dinâmicos são resolvidos utilizando o método ESL. A função a ser minimizada é a massa da treliça, que está sob restrições de tensão e deslocamento, onde as variáveis de projeto são as áreas da seção transversal dos membros. Além disso, uma interface utilizando ANSYS e MATLAB é desenvolvida para uma abordagem modular, na qual a análise via elementos finitos e a otimização possam ser realizadas separadamente. Este processo viabiliza a otimização de estruturas que apresentam comportamentos não lineares a partir da utilização de diversos softwares comerciais disponíveis no mercado.
Structural optimization subject to dynamic loading is a challenging problem in many aspects, starting with the large number of constraints that must be respected at all instants of time. Furthermore, the computational cost to evaluate the gradients of these constraints is significantly high and requires a large storage space. In the literature, some methods reduce the number of constraints evaluating at selected instants of time, such as the worst case. Alternatively, a single equivalent functional is constructed to eliminate the time dependence by integrating the violated constraints over time. In this work, the Equivalent Static Load (ESL) method is used, in which the original dynamic problem is reduced into a number of static linear optimization problems with multiple load cases. An attractive feature of this method is the possibility of solving non-linear problems, avoiding the high cost due to repeated structural analyzes and constraint calculations. Classical problems of plane trusses subjected to dynamic loads are solved using the ESL method. The function to be minimized is the truss mass, which is subjected to stress and displacement constraints, where the design variables are the cross-sectional areas of the members. In addition, an interface using ANSYS and MATLAB was developed for a modular approach, in which finite element analysis and optimization can be performed separately. This process makes possible the optimization of structures that present non-linear behavior from the use of most structural analysis software packages available on the market.

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Bahai, Hamid R. S. « A hybrid method for load, stress and fatigue analysis of drill string screw connectors ». Thesis, Queen Mary, University of London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284406.

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Campbell, Patrick George. « Critically examining the capacity of wellness measures as a method of monitoring training load and the athlete training response ». Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/134391/1/Patrick_Campbell_Thesis.pdf.

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Athlete load monitoring is standard in high-performance sports environments, and is principally utilised to maximise performance and physiological adaptations, while limiting the deleterious costs of training and competition. Modified wellness questionnaires are a popularly utilised method of load monitoring, and are commonly used to evaluate the athlete training response from a holistic viewpoint. However, there remains a lack of evidence to support their use. This thesis investigated the dosage effects of wellness measures on controlled acute and chronic modulations in training intensity and overall volume; and the associations between wellness and psychological states, load monitoring markers and common performance measures.

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Jonsson, Björn. « A digital image correlation method for detection of fatigue cracks in non-load carrying T-joints ». Thesis, KTH, Lättkonstruktioner, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234905.

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In dynamical loaded welded structures fatigue life is often a limiting factor. Common practise is to reduce nominal stress by increased material thickness which leads to oversized, heavy structures. Those practises are replaced by improvement of production and designingtechniques to utilize better properties of high strength steels.When improving for example quality of welds, issues can occur that standards today did not consider and new test methods can be valuable.In this thesis a method for crack detection in non-load carrying T-joints have been tested. Specimens are made from 6mm Strenx 960MC high strength steel. DIC-analyses is made on frames captured be a high-speed camera during fatigue testing. Hypothesis is that crackpropagation starts when relative strain is higher than 10% per 10 000 cycles.Validation of the method is done by beachmarks from variable stress range during the fatigue test. With the same occurrence as framesets for DIC-analyse. Number of beachmarks agree well with the segment when relative strain indicates crackpropagation in a point at the weld toe.
Svetsade konstruktioner under dynamisk belastning blir utmattningshållfastheten ofta en begränsande faktor. Praxis har varit att öka materialtjockleken för att minska nominella spänningen, vilket fungerar bra. Användning av höghållfasthetsstål som tillåter slankarekonstruktioner och viktminskningspotential är det tillvägagångssättet inte aktuellt.Ökad kontroll av svetskvalitet i kombination med kunskap om vilka defekter som påverkar utmattningslivslängden ger möjligheter till viktoptimering. I detta examensarbete har en metod för sprickdetektering under utmattningstest av ickelastöverförande T-förband testats. Provstavar tillverkade av 6mm Strenx 960MC stål. DIC analys genomfördes på bildrutor inspelade av en höghastighetskamera med hypotesen att sprickpropagering detekteras vid 10% relativ töjningsökning per 10 000 cykler.Validering utförs med hjälp av ”beachmarks” från varierande spänningsnivåer under utmattningstestet. Bildsekvensenerna som fångas med höghastighetskameran sammanfaller med slutet på ena spänningsnivån. Antalet ”Beachmarks” visar en sprickfront på ca 200  300μm vid 10% relativ töjning.

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Gilbert, Andy Michael. « Validation of a laboratory method for accelerated fatigue testing of bridge deck panels with a rolling wheel load ». Thesis, Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/gilbert/GilbertA0512.pdf.

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The Western Transportation Institute (WTI) was engaged by the California Department of Transportation (Caltrans) to investigate the performance of various bridge deck rehabilitation surface treatments. This study requires that full-scale reinforced bridge deck slabs be tested in a laboratory environment. The deck slabs are to be tested by applying repeated passes of a rolling wheel load to damage the slabs to certain levels of deterioration. The slabs will be mounted in a frame for testing to impose specific support constraints necessary to generate realistic box girder bridge behavior. The intent of the present study was to design the panel support frame and validate that it provides the required restraint conditions needed for testing as well as to determine if it will be possible to generate the damage required in future deck slabs in a realistic time frame. This validation was accomplished by performing an experimental study in which a sample test slab was loaded to failure in one of the bays of the support frame. The slab was loaded with a stationary hydraulic jack over a contact area resembling that of a standard dual tire footprint. In addition, the finite element modeling software, ANSYS, was used to model the laboratory test to aid in interpreting the experimental results. The results from the laboratory test and the related findings from the finite element model were presented in terms of cracking behavior, deflection histories, strain measurements in the steel reinforcement, ultimate capacity, and mode of failure. The results were used in conjunction with the finite element model to validate the performance of the support frame. It was determined that the support frame provides the restraint conditions needed to create the in-service stress conditions of interest in the bridge deck slabs. A fatigue life model that was developed by past researchers was used to assess the expected performance of the deck specimens under the proposed rolling wheel loads.

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Lindholm, Martin, Metin Uçar et Nermin Dzanic. « The load carrying unit of articulated haulers : Analysis of the welded connections ». Thesis, Växjö University, School of Technology and Design, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-5818.

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Detta examensarbete handlar om finita element analys av svetsade förband i korgen på Volvo dumpern A40E. Det genomfördes i samarbete med Volvo CE i Braås. Uppgiften var att ge företaget en lämplig lösning för att minska mängden svetsskarvar på den främre delen av lastenheten. För att uppnå detta har en rad analyser genomförts med hjälp av CATIA och ANSYS på både de befintliga och de justerade (potentiella ersättare) svetsade förbanden. Analyserna visar att utmatningshållfastheten av svetsade förband huvudsakligen beror på inbränningsdjupet. Med andra ord, förstärka svetsförband genom större inbränning är mer fördelaktigt än att använda mer svets på utsidan. Slutsatsen blev att både produktionstid och kostnad kan minskas genom justering av de svetsade förbanden. Eftersom svetsförband på lastenheten är sammankopplade bör mer omfattande studier som inkluderar alla svetsar genomföras för att uppskatta effekterna av liknande justeringar.

The work presented in this master thesis is about the finite element analysis of the welded connections in load carrying unit of the articulated hauler, Volvo A40E. It was performed in cooperation with Volvo CE in Braås. The task was to provide the company with an appropriate solution to reduce the amount of weld used on the front part of the load carrying unit. To accomplish this, a series of analyses utilising CATIA and ANSYS was performed on both existing and adjusted (potential replacement) welded connections. The analyses brought to light the fact that the fatigue resistance of welded connections significantly depends on the penetration depth. In other words, reinforcing the welded connections by deeper penetration is more beneficial than providing support from outside through thicker weld. It was concluded that applying adjusted welds lessens both the production time and cost. Nevertheless, since the welds on the load carrying unit are correlated; more extensive studies covering all welds should be carried out to estimate the impacts of similar replacements.

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Dossou, Dossouvi. « Fatigue thermique d'un polycarbonate : modèle de prédiction de durée de vie d'éprouvettes entaillées ». Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL135N.

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Le polycarbonate est de plus en plus utilisé en ingénierie à cause de ses bonnes propriétés mécaniques. Il n'existe pas de procédure de dimensionnement bien établie pour tenir compte de la présence d'une concentration locale de déformation ou de contrainte dans une structure soumise à un chargement cyclique. Nous proposons un modèle de prévision de la durée de vie d'éprouvettes entaillées d'un polycarbonate en fatigue thermique. Le banc d'essai de fatigue thermique conçu est constitué d'un bâti assurant le maintien de l'éprouvette, d'un système de chauffage et de refroidissement, d'une unité de mesure et de régulation de la température, d'un système extensometrique ainsi que d'une unité informatique permettant la réalisation des cycles thermiques et l'asservissement précis des équipements. Des essais en traction isotherme sont réalisés pour déterminer les lois de comportement de notre polycarbonate dans l'intervalle de température des cycles thermiques. Les essais de cyclage thermique sur des éprouvettes lisses permettent de déterminer les lois de fatigue du matériau en terme d'énergie de déformation dissipée. L’analyse par la méthode des éléments finis permet de déterminer les coefficients de concentration de contrainte et la densité d'énergie de déformation dissipée en fond d'entaille. Notre modèle est obtenu en combinant la loi de fatigue du matériau et la loi d'évolution de la densité d'énergie de déformation dissipée en fond d'entaille en fonction du coefficient de concentration de contrainte. Ce modèle simple peut être utilisé pour déterminer la résistance à la fatigue d'autres matériaux et sous différents modes de sollicitation

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Livres sur le sujet "Equivalent fatigue load method"

Brondsted, Povl. Fatigue testing : Establishment of a standard method for fatigue testing under variable load amplitudes simulating offshore load spectra. Roskilde : Riso National Laboratory, 1988.

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Chapitres de livres sur le sujet "Equivalent fatigue load method"

Kisu, Hiroyuki, et Gui Ming Rong. « Identification of a Defect Using the Equivalent Load Method ». Dans Key Engineering Materials, 2441–44. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.2441.

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Jing-Li, Wang. « A Fast Method for Calculating the Node Load Equivalent Impedance Module ». Dans Electrical Engineering and Control, 599–603. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-21765-4_73.

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Srinivas, G. Lakshmi, et Arshad Javed. « Multi-body Topology Optimization of Connecting Rod Using Equivalent Static Load Method ». Dans Lecture Notes in Mechanical Engineering, 427–35. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1769-0_39.

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Kim, Myung Hyun, Sung Won Kang, Chung In Ha, Jae Myung Lee, Jeong Hwan Kim et Sung Soo Na. « Fatigue Strength Evaluation of Load-Carrying Fillet Weldments under Out-of-Plane Bending Load Using Structural Stress Method ». Dans Key Engineering Materials, 2069–72. Stafa : Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.2069.

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Wang, R. G., W. J. Xu, Z. Hua et X. Q. Zhou. « Research on the influence of slamming load on ship fatigue damage and its calculation method ». Dans Trends in Maritime Technology and Engineering Volume 1, 481–91. London : CRC Press, 2022. http://dx.doi.org/10.1201/9781003320272-54.

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Liu, Mingxuan, Xinyang Fan, Danrong Song, Bin Zheng et Meng Zhang. « Fatigue Analysis Method of Steel Containment of Floating Nuclear Power Plant ». Dans Springer Proceedings in Physics, 1046–59. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_88.

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AbstractFloating nuclear power plant (FNPP) is a movable nuclear power plant built on the floating platform, which can provide clean and stable power for remote coastal areas, and are currently a hot research topic in the field of nuclear power. The steel containment is located in the reactor compartment of the FNPP and it is an important safety guarantee structure. Fatigue and fracture have been an important issue for ship and offshore structures for a long time. Fatigue failure of containment will have serious consequences.In order to research the fatigue life analysis method of steel containment of the first FNPP in China, the paper adopts miner linear cumulative damage theory and spectral analysis method, based on the American Society of Mechanical Engineers (ASME) standards and relevant standards of China Classification Society (CCS), and uses AQWA to analyze Wave load of FNPP. The hydrodynamic calculation results are imported into finite element model to analyze the structural response of each point of containment, and calibrate the transfer function data of each key point by using the linear system theory and regular wave periodic evaluation method. The fatigue analysis of each point is carried out according to the transfer function and the wave dispersion diagram drawn by the forty years monitoring sea conditions of the working sea area of the FNPP. The result shows that the fatigue life of steel containment is superior and meets the service requirements.

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Matsufuji, Y., et T. Ohkubo. « On the Estimating Method of Fatigue Strength of the Brittle Materials under Repeated Impulsive Bending Load ». Dans Fracture of Concrete and Rock, 70–79. New York, NY : Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4612-3578-1_8.

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Cui, Jialin, Lijuan Li, Meng Zhang, Hongbing Liu et Xianqiang Qu. « Dynamic Response Analysis of Floating Nuclear Power Plant Containment Under Marine Environment ». Dans Springer Proceedings in Physics, 609–23. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_53.

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AbstractFloating nuclear containment is in a harsher environment than conventional onshore nuclear containment. In view of the Marine environment under the condition of floating nuclear power plant containment structure safety, combined water dynamics and structural mechanics, considering the containment response under random movement of hull in the Marine environment, the influence of the containment structure load calculation, thus checking containment when working in pile structure safety, provide theoretical basis for the safe operation of floating nuclear power plants. In this paper, taking a floating nuclear power plant as an example, ANSYS 2021R1, Workbench, Fluent and other software of finite element analysis are used to conduct fatigue simulation of floating nuclear power plant. The time course curve of the 6-dof motion of the ship’s center of gravity is obtained, then, a remote displacement method is adopted to transfer the hull motion to the containment vessel to realize the numerical simulation of the containment vessel movement with the hull, thus to solve maximum normal stress and strain, the maximum load component of containment bearing under the action of Marine environmental load is obtained. The results show that the maximum stress and strain of the vessel increase obviously in the moving state compared with the static state of the vessel, which indicates that the random motion response of the vessel must be considered in the structural safety analysis of the floating nuclear power plant containment.

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« equivalent-load method ». Dans Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 480. Berlin, Heidelberg : Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-41714-6_51519.

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Zenner, H., J. Liu et C. Sanetra. « Fatigue Behaviour under Uniaxial and Multiaxial Service Load ». Dans The Rainflow Method in Fatigue, 170–81. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-7506-0504-5.50027-8.

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Actes de conférences sur le sujet "Equivalent fatigue load method"

Tibbits, Patrick. « Fatigue Load Equivalent to Distribution of Loads From the US Population ». Dans ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-35678.

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In seeking to simplify fatigue life calculations for components of fitness equipment, this paper develops a general expression for the user weight Le which, in NT cycles, generates the same fatigue damage as a set of user weights {Li} described by a probability density function fi = Ni/NT, where each Li gets applied for Ni cycles and Σ Ni = NT. The derivation of the method goes beyond the textbook development of equivalent load by retaining geometric, material, and loading parameters throughout the derivation. The expression allows exploration of the effect of the geometry of the mechanical component, material properties, and loading on the value of the user weight Le which simulates the set of user weights {Li}. The paper explores a range of stress-life exponent b typical of common steels. The paper explores the complete range of stress ratio R ∈ (-1, 1). The paper explores the combined effect of the component’s ultimate tensile strength and the ratio between applied load and stress. These last two parameters determine the user weight Lb which causes single-cycle fracture of the component. The results indicate a strong dependence of Le on stress ratio R, stress-life exponent b, and on breaking weight Lb. The paper proposes guidelines for assignment of Le in the special case where the {Li} arise from body weights of the US population.

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Heinz, Benedikt. « AREVA Fatigue Concept : A New Method for Fast Fatigue Evaluation ». Dans ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25935.

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Within the AREVA Fatigue Concept (AFC) a new method for fast fatigue evaluation for highly loaded nuclear power plant components was developed. This method uses FAMOS (FAtigue MOnitoring System) measured data from the outside surface of a pipe and can evaluate a fatigue level for the component for the thermal event plug flow. The measuring location of FAMOS is chosen close to a fatigue relevant component and the points of interest are at the inner surface of the component. The calculated inner wall temperature time history will be transferred to the inner surface of the component. The thermal load cycles are well known after that step and the stress time history and also the strain rates would be calculated with the Green’s function approach. Unit transients will be used to calculate principle stresses and shear stresses in all fatigue relevant locations within the monitored component. Pressure cycles will also be evaluated with the Green’s function approach. After the calculation of the equivalent stresses the mechanical load cycles can be classified by the use of the rainflow algorithm. Comparisons (Miner’s rule) with the fatigue curve results in fatigue levels for all relevant locations within a component. In the current approach, the conservatism will be reduced with this method, and an enveloping fatigue level can still be calculated. In another words, for highly loaded components, using the current methodology can provide a more realistic stress calculation and enveloping fatigue level calculation. Depending on the number of load cycles, the new and more stringent requirements can be complied.

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Ahn, Hyeonjeong, et Hyunkyoung Shin. « Fatigue Analysis of a 12-MW Wind Turbine Blade ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78214.

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In 2017, the MHI Vestas released a 9.5-MW offshore wind turbine. It is also actively researching and developing a 10-MW offshore wind turbine. As the capacity of a wind turbine increases, the sizes of all its system components, including length and weight, correspondingly increase. Consequently, as a wind turbine becomes larger, it becomes necessary to analyze the fatigue load applied to its entire system. The first reason for such an analysis is to achieve a safe but not overly designed large wind turbine. Second, most wind turbine accidents involve aging turbines and are related to fatigue analysis. Accordingly, the purpose of fatigue analysis is to safely design a wind turbine that sustains repeated loads within its design life. In this study, the blades and loads for the fatigue analysis of a 12-MW floating offshore wind turbine are calculated based on the National Renewable Energy Laboratory (NREL) 5-MW wind turbine blades. The calculated loads are applied to the Markov matrix through a preprocessing, such as the cycle counting method. Finally, the equivalent fatigue load is estimated based on both mean and range. In this study, only the equivalent fatigue load on the turbine blade is calculated. However, if fatigue analysis is to be performed for all parts using equivalent loads, it is possible to design the wind turbine to fully withstand such loads throughout its design life, and prevent the overdesign of each part as well.

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Hu, Dianyin, Jiaming Wei, Huawei Liu, Wulin Si et Rongqiao Wang. « Fatigue Crack Growth of Multiple Load Path Structure Under Combined Fatigue Loading : Part I — Numerical Simulation ». Dans ASME Turbo Expo 2014 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25719.

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A new numerical method for the analysis of fatigue crack growth in the multiple load path structure under low-high cycle combined fatigue (L-HCCF) loading is proposed in this paper. Firstly, vibrational stress is obtained through dynamic response analyses considering joint dry friction between the turbine blade and the turbine disc based on equivalent linearization and micro-slip model. Then, the crack growth in the fir-tree attachment is simulated under vibrational stress superimposed with low cycle fatigue loading through fracture mechanics (FM) analysis. Vibrational loading in the fir-tree attachment is redistributed with the crack propagation because of this multiple load path structure. Thus, dynamic response analysis is re-performed on the turbine attachment. At last, the crack growth life of multiple load path structure under L-HCCF loading is predicted based on the linear cumulative damage model. The predicted life agrees well with the experimental data of actual turbine component, which verifies that the new numerical method for the analysis of fatigue crack growth in the multiple load path structure under L-HCCF loading is reasonable and feasible.

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Krouse, Charles R., Grant O. Musgrove, Taewoan Kim, Seungmin Lee et Muhyoung Lee. « Novel and Applicable Method to Determine Equivalent Strain Range and Equivalent Strain Direction Under Multiaxial Non-Proportional Loading ». Dans ASME Turbo Expo 2019 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90174.

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Abstract When considering mechanical components that are subjected to complex loading conditions, it is difficult to achieve accurate predictions of low-cycle fatigue life. For multiaxial and non-proportional loads, the principal strain directions vary in three-dimensional space with time. The commonly accepted methods to determine fatigue life under such loading conditions are based on a critical plane approach, and they rely heavily on accurate strain range estimates. However, there is no singly accepted method to determine the critical plane, equivalent strain magnitude, or equivalent strain direction. Furthermore, current suggestions are computationally intensive and challenging to implement. This paper offers a novel and concise method to accurately determine equivalent strain range and equivalent strain direction under multiaxial, non-proportional loading in three-dimensional space. A practical approach is provided for implementing the method, and an example of an application using a finite element model of a first stage turbine blade is discussed. To demonstrate the approach, ANSYS Mechanical was used to simulate a turbine blade under transient loading conditions and to determine the resulting strains. Equivalent strain range results were applied to a Coffin-Manson relation to determine the low-cycle fatigue life of every node within the finite element model of the first stage turbine blade. The post-processing of the strain predictions, which yielded the equivalent strain range and equivalent strain direction, is discussed in detail.

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Ligaj, Bogdan, et Karolina Karolewska. « Fatigue life calculations of structural elements by means of equivalent load spectrum and material properties for LCF and HCF ». Dans INTERNATIONAL CONFERENCE ON THE METHODS OF AEROPHYSICAL RESEARCH (ICMAR 2018). Author(s), 2018. http://dx.doi.org/10.1063/1.5066397.

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Pan, Ting, De Gao, Suo Zhang, Yunkai Gao, Lei Wang, Furong Xie et Jiachi Tong. « Research on Fatigue Damage of Independent Suspension Support Structure for a Commercial Vehicle Based on Load Spectrum of Basic Vehicle ». Dans WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0807.

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<div class="section abstract"><div class="htmlview paragraph">In this paper, an equivalent conversion method is proposed to apply the six-dimensional force road spectrum of the four-axle vehicle on the same platform to the three-axle through the axle load comparison. Further, the feasibility of the devolved equivalent conversion method is verified, and the fatigue performance improvement of the wishbone support structure of a commercial vehicle is finally achieved. Specifically, firstly, the load spectrum at each attachment point of the suspension for the three-axle vehicle is obtained through the iteration of the multi-body dynamic model. Furthermore, the finite element model of the suspension for the three-axle vehicle is established; the analysis of fatigue life for the suspension structure is performed by extracting stress amplitude through the multi-axis cyclic counting method and calculating equivalent force amplitude through McDiarmid’s criterion, combined with the SN curve of the material. Finally, the prediction and optimization design of the fatigue weak position for the wishbone support are realized. The results of the three-axle vehicle after trial production show that the fatigue damage position of the control arm bracket is consistent with the simulation prediction, and the fatigue performance of the optimized suspension is significantly improved. Therefore, the developed method can be applied to the fatigue analysis of replacement vehicle components, which can shorten the design cycle and improve the efficiency under the premise of ensuring the accuracy and reliability of fatigue life prediction.</div></div>

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Zhang, Wei, Huili Liu, Qiang Wang et Shan Jiang. « Fatigue Life Prediction Using Strain Intensity Factor and Equivalent Initial Flaw Size ». Dans ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66505.

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In this paper, an effective approach is developed to evaluate fatigue life of smooth specimens of 316 austenitic stainless steel under the fully reversed loading condition based on strain intensity factor and the equivalent initial flaw size (EIFS) concept. The strain intensity factor is indicated to be a better driving parameter to correlate with the fatigue crack growth rate, especially for the fully reversed load condition and the low cycle fatigue region. EIFS is an effective approach to account for complex process of the crack initiation and small crack propagation, which can be calculated by correlating the fatigue limit strain with fatigue threshold strain intensity factor. The fatigue limit strain is obtained from experimental data by analyzing the asymptotic behavior of the fatigue life curve. The driving force of crack growth is expressed in strain intensity factor. Then the fatigue life could be calculated by integrating the crack growth rate from integral lower limit EIFS to integral upper limit critical crack length ac. The experimental data of 316 austenitic stainless steel are employed to validate the proposed model. The good agreements are observed. It has shown that strain-intensity-factor-based approach could be a good method for fatigue life evaluation.

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Braccesi, Claudio, Filippo Cianetti et Luca Landi. « Random Loads Fatigue : The Use of Spectral Methods Within Multibody Simulation ». Dans ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84453.

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The evaluation of the fatigue damage performed by using the Power Spectral Density function (PSD) of stress and strain state is proving to be extremely accurate for a family of random processes characterized by the property of being stationary. The present work’s original contribution is the definition of a methodology which extracts stress and strain PSD matrices from components modelled using a modal approach (starting from a finite element modelling and analysis) within mechanical systems modelled using multibody dynamic simulation and subject to a generic random load (i.e. multiple-input, with partially correlated inputs). This capability extends the actual stress evaluation scenario (principally characterised by the use of finite element analysis approach) to the multibody dynamic simulation environment, more powerful and useful to simulate complex mechanical systems (i.e. railway, automotive, aircraft and aerospace systems). As regards the fatigue damage evaluation, a synthesis approach to evaluate an equivalent stress state expressed in terms of the PSD function of Preumont’s “equivalent von Mises stress (EVMS)”, starting from the complete stress state representation expressed in terms of PSD stress matrix and easily usable in the consolidated spectral methods, is proposed. This approach allows and has allowed the use of the above methods such as the Dirlik formula as a damage evaluation method. An additional result is the conception and implementation of a frequency domain method for the component’s most probable state of stress, allowing quickly identification of the most stressed and damageble locations. The described methodologies were developed and embedded into commercial simulation codes and verified by using as a test case a simple reference multibody model with a simple flexible component.

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Farrow, Gary H., Andrew E. Potts, Andrew A. Kilner, Phillip P. Kurts, Simon Dimopoulos et Eric Jal. « Development of a New, Correlated FEA Method of Assessing Mooring Chain Fatigue ». Dans ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95882.

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Abstract The first phase of the Chain FEARS (Finite Element Analysis of Residual Strength) Joint Industry Project (JIP) aimed to develop guidance for the determination of a rational discard criteria for mooring chains subject to severe pitting corrosion which, based on current code requirements, would otherwise require immediate removal and replacement. Critical to the ability to evaluate the residual fatigue life of a degraded chain, is to have an accurate estimate of the chain in its as-new condition, thereby providing a benchmark for any loss in fatigue life associated with severe corrosion or wear. A large collection of fatigue test data was collated for comparison and to establish underlying trends in as-new mooring chain fatigue response. A non-linear multi-axial Finite Element Analysis (FEA) fatigue assessment method was developed to correlate against available as-new chain link fatigue test data and underlying failure trends as part of the JIP achieving this critical requirement. It was established that the linear FEA fatigue method currently employed in the industry is too simplistic and does not correlate with the fatigue test data, whereas an alternative method of assessing fatigue based on FEA, developed with respect to the DNV B1 material curve, correlates well with the available physical fatigue test data. The FEA method uses a non-linear chain link FEA and multi-axial stress fatigue calculation method to determine an equivalent Stress Magnification Factor (SMF). This method achieves good correlation of predicted utilisations and associated cycles-to-failure with fatigue test data and in respect of critical locations with evidenced failure locations. The method of equivalent SMF calculation accounted for the significant effects on fatigue performance including proof load induced residual stress, mean stress levels and the increase in material fatigue endurance associated with increased steel UTS (i.e. increased offshore mooring chain grade). The analytical method developed in this study achieved a high degree of correlation with as-new chain fatigue test data, and should enable the accurate prediction of fatigue stresses around a link and in particular for irregular geometry associated with corrosion degraded chain links.

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Rapports d'organisations sur le sujet "Equivalent fatigue load method"

Messner, M. C., et T. L. Sham. Development of a multiaxial deformation measure and creep-fatigue damage summation for multiple load cycle types in support of an improved creep-fatigue design method. Office of Scientific and Technical Information (OSTI), juin 2019. http://dx.doi.org/10.2172/1601810.

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Bao, Jieyi, Xiaoqiang Hu, Cheng Peng, Yi Jiang, Shuo Li et Tommy Nantung. Truck Traffic and Load Spectra of Indiana Roadways for the Mechanistic-Empirical Pavement Design Guide. Purdue University, 2020. http://dx.doi.org/10.5703/1288284317227.

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The Mechanistic-Empirical Pavement Design Guide (MEPDG) has been employed for pavement design by the Indiana Department of Transportation (INDOT) since 2009 and has generated efficient pavement designs with a lower cost. It has been demonstrated that the success of MEPDG implementation depends largely on a high level of accuracy associated with the information supplied as design inputs. Vehicular traffic loading is one of the key factors that may cause not only pavement structural failures, such as fatigue cracking and rutting, but also functional surface distresses, including friction and smoothness. In particular, truck load spectra play a critical role in all aspects of the pavement structure design. Inaccurate traffic information will yield an incorrect estimate of pavement thickness, which can either make the pavement fail prematurely in the case of under-designed thickness or increase construction cost in the case of over-designed thickness. The primary objective of this study was to update the traffic design input module, and thus to improve the current INDOT pavement design procedures. Efforts were made to reclassify truck traffic categories to accurately account for the specific axle load spectra on two-lane roads with low truck traffic and interstate routes with very high truck traffic. The traffic input module was updated with the most recent data to better reflect the axle load spectra for pavement design. Vehicle platoons were analyzed to better understand the truck traffic characteristics. The unclassified vehicles by traffic recording devices were examined and analyzed to identify possible causes of the inaccurate data collection. Bus traffic in the Indiana urban areas was investigated to provide additional information for highway engineers with respect to city streets as well as highway sections passing through urban areas. New equivalent single axle load (ESAL) values were determined based on the updated traffic data. In addition, a truck traffic data repository and visualization model and a TABLEAU interactive visualization dashboard model were developed for easy access, view, storage, and analysis of MEPDG related traffic data.

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Ramakrishnan, Aravind, Ashraf Alrajhi, Egemen Okte, Hasan Ozer et Imad Al-Qadi. Truck-Platooning Impacts on Flexible Pavements : Experimental and Mechanistic Approaches. Illinois Center for Transportation, novembre 2021. http://dx.doi.org/10.36501/0197-9191/21-038.

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Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.

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RECONSTRUCTION OF FATIGUE DAMAGE STATE OF IN-SERVICE STEEL BRIDGES WITHOUT LOAD INFORMATION. The Hong Kong Institute of Steel Construction, août 2022. http://dx.doi.org/10.18057/icass2020.p.259.

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The load history of most in-service steel bridges was missing, and the realization of structural fatigue damage state reconstruction was an important prerequisite to secure the safety of structures in service. Based on the principle of damage equivalence, a method for assessing the fatigue damage state of the steel bridge during service is proposed. Firstly, the fatigue damage accumulation under different load spectra is calculated by linear damage accumulation criterion. On this basis, the fatigue damage of welded details is evaluated using the fatigue crack information obtained from the observation of inservice steel bridges. The linear combination of load spectrum equivalent to structural fatigue damage is resolved, and the fatigue damage assessment and forecast of steel bridges in service are accomplished. This paper provides a new idea and method for fatigue damage assessment of in-service steel bridges.

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CALCULATION METHOD OF ULTIMATE LOAD BEARING CAPACITY OF CONCRETE FILLED STEEL TUBULAR LATTICE COLUMNS. The Hong Kong Institute of Steel Construction, août 2022. http://dx.doi.org/10.18057/icass2020.p.095.

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To investigate the influence of eccentricity ratio and slenderness ratio on the mechanical properties of eccentric compressed concrete filled steel tubular (CFST) lattice column, the ultimate bearing capacity tests of 20 K shape arrangement lacing strip of four-tube CFST columns were conducted. Based on the stress-strain relationship of CFST and the influence of shear deformation, the equilibrium equation of the mid-section is established and a numerical method for the ultimate bearing capacity of CFST lattice column is proposed. The slenderness reduction coefficient calculation model and equivalent slenderness ratio formula of CFST lattice column are established. Combined with the numerical results and the slenderness ratio reduction coefficient calculation model, the formula of slenderness ratio reduction coefficient is put forward. The comparison between theoretical analysis and experimental results shows that the calculation method of elastic-plastic ultimate bearing capacity of CFST lattice column proposed in this paper is quite accurate. The research outcomes can provide a reference for the application of CFST lattice column and revision of current specifications.

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FATIGUE TESTS OF COMPOSITE DECKS WITH MCL CONNECTORS. The Hong Kong Institute of Steel Construction, décembre 2022. http://dx.doi.org/10.18057/ijasc.2022.18.4.7.

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Full-scale fatigue tests were performed on three composite decks with the MCL (modified clothoid) connectors to investigate their fatigue performance. Fatigue life and failure mode of the composite bridge decks were explored by measuring the specimens with three different stress amplitudes. The deflection, strain, carrying capacity, and stiffness degradation of the composite decks were measured and analyzed in the test. In addition, parameter analysis was performed using finite-element method in this study. Results showed that the mechanical performance of the composite decks accorded with the plane-section assumption under constant amplitude load, and the fatigue failure mode of the composite decks was the local fracture of the bottom steel plate. The stiffness degradation law and S-N curve were obtained in this study. Moreover, the concrete slab depth had a remarkable effect on the fatigue performance of the composite decks.

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COLD FORMED STEEL SHEAR WALL RACKING ANALYSIS THROUGH A MECHANISTIC APPROACH : CFS-RAMA. The Hong Kong Institute of Steel Construction, septembre 2022. http://dx.doi.org/10.18057/ijasc.2022.18.3.2.

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Cold-formed steel shear wall panels are an effective lateral load resisting system in cold-formed steel or light gauge constructions. The behavior of these panels is governed by the interaction of the sheathing - frame fasteners and the sheathing itself. Therefore, analysis of these panels for an applied lateral load (monotonic/cyclic) is complex due to the inherent non-linearity that exists in the fastener-sheathing interaction. This paper presents a novel and efficient, fastener based mechanistic approach that can reliably predict the response of cold-formed steel wall panels for an applied monotonic lateral load. The approach is purely mechanistic, alleviating the modelling complexity, computational costs and convergence issues which is generally confronted in finite element models. The computational time savings are in the order of seven when compared to the finite element counterparts. Albeit its simplicity, it gives a good insight into the component level forces such as on studs, tracks and individual fasteners for post-processing and performance-based seismic design at large. The present approach is incorporated in a computational framework - CFS-RAMA. The approach is general and thereby making it easy to analyze a variety of configurations of wall panels with brittle sheathing materials and the results are validated using monotonic racking test data published from literature. The design parameters estimated using EEEP (Equivalent Energy Elastic Plastic) method are also compared against corresponding experimental values and found in good agreement. The method provides a good estimate of the wall panel behavior for a variety of configurations, dimensions and sheathing materials used, making it an effective design tool for practicing engineers.

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SOUND RADIATION OF ORTHOTROPIC STEEL DECKS SUBJECTED TO MOVING VEHICLE LOADS. The Hong Kong Institute of Steel Construction, août 2022. http://dx.doi.org/10.18057/icass2020.p.052.

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Orthotropic steel decks (OSDs) are widely used in the construction of steel bridges due to their high bearing capacity and low material consumption. Current investigations into OSDs mainly focus on issues associated with static, stability, fatigue, etc. However, from the perspective of dynamics, structures with low dead loads may be susceptible to excessive vibration and noise, which occurs when shocks caused by moving traffic loads are transferred to the bridge deck and other components. Hence, bridge vibration and the associated noise are critical issues in steel bridges. This paper investigates the vibration and noise characteristics of OSDs under moving vehicle loads by using analytical method. First, the forced vibration response of the OSDs is solved by the Finite Element Method(FEM), and then the obtained response is used as the boundary condition of the OSDs boundary element model to solve the acoustic radiation. Finally, the variation rules of the vibration and sound radiation of the OSDs are analyzed when the load parameters, boundary conditions and structural parameters are changed. The results show that when analyzing the high-frequency vibration and noise of the OSDs, the all-shell-element model should be selected. The high frequency part of vibration and sound pressure of the OSDs is greater than the low frequency part under moving load. Increasing the load speed will increase the low-frequency part of vibration and sound pressure, but increasing the load eccentricity will have the opposite result. Strengthening the boundary constraints and increasing the number of ribs will suppress the vibration and reduce the sound pressure.

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