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Journal articles on the topic "Load spectra"

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Hu, Sheng, Fujie Zhou, and Tom Scullion. "Load Spectra–Incorporated Fatigue Cracking Model Implementation and Case Study." Transportation Research Record: Journal of the Transportation Research Board 2640, no. 1 (January 2017): 1–10. http://dx.doi.org/10.3141/2640-01.

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Traffic loading is one of the key factors that may cause asphalt concrete pavement fatigue cracking. Axle load spectra input provides an opportunity for evaluating the pavement response under real traffic loads throughout the pavement design life. This paper describes the methodology of incorporating axle load spectra into the mechanistic–empirical fatigue cracking model that uses a fracture mechanics method to determine crack propagation. The paper also presents the incorporation of the method into the Texas mechanistic–empirical flexible pavement design system. Several load spectra cases were studied, and the percentages of the corresponding fatigue cracking areas were predicted and compared. The comparison results confirmed the necessity of load spectra analysis. Overall, the implemented load spectra–incorporated asphalt concrete fatigue cracking model generated rational results. Further research is continuing on field validation and calibration.
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Mirosław, Rodzewicz, Głowacki Dominik, and Hajduk Jaroslaw. "Comparative Analysis of the Load Spectra Recorded During Photogrammetric Missions of Lightweight Uavs in Tailless and Conventional Configurations." Fatigue of Aircraft Structures 2022, no. 14 (December 1, 2022): 114–34. http://dx.doi.org/10.2478/fas-2022-0009.

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Abstract The purpose of this article is to present the results of the investigation regarding the differences of the load spectra of two unmanned fixed-wing aircraft performing photogrammetry missions: X-8 (flying wing) and PW-ZOOM (conventional configuration). The focus was on the analysis of a number of load cycles for various load increments within the range of the operational loads. The load spectra were determined using the acceleration signal recorded in the autopilot logs as an input. This signal was transferred to the chain of local extreme values scaled in the form of discrete load levels, and then the transfer arrays were derived with use of the rainflow counting algorithm. On this basis, the incremental load spectra were determined for each flight. These load spectra were subjected to statistical analyses to determine the load spectra representative of the flight sessions in a few ways between non-conservative (i.e., focused on average load histories) and conservative (i.e., focused on the worst load histories observed during the flight session). Finally, the fatigue life was calculated by having the structural element of the assumed fatigue properties subjected to the load spectra of both airplanes. A large (exceeding one order of magnitude) difference in the number of load cycles for larger load increments in the analyzed load spectra was shown. This difference is related to the different dynamic characteristics of the two aircraft, in particular the gust response. As a result, there is a several-fold difference in fatigue life.
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Zhao, Jingnan, Hao Wang, Pan Lu, and Jiaqi Chen. "Mechanistic–Empirical Analysis of Pavement Performance Considering Dynamic Axle Load Spectra Due to Longitudinal Unevenness." Applied Sciences 12, no. 5 (March 2, 2022): 2600. http://dx.doi.org/10.3390/app12052600.

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Pavement distresses are induced by mechanistic responses in pavement structure subjected to dynamic loads of moving vehicles. Pavement surface evenness deteriorates as pavement distresses propagate, which results in dynamic axle loads and faster pavement deterioration. It is vital to consider the dynamic axle load spectra to predict pavement deterioration using traffic-monitoring data. This study aimed to evaluate the effect of dynamic loads and overweight traffic on asphalt pavement overlay performance using mechanistic–empirical (M–E) pavement analysis. The relationship between dynamic load coefficients (DLCs), axle loads, and international roughness index (IRI) was obtained for accurate quantification of dynamic axle loads. Then the dynamic axle load spectra were derived by shifting the static axle load spectra in weigh-in-motion (WIM) data, given the DLC value. AASHTOWare Pavement ME software was used to analyze pavement performance with static and dynamic axle load spectra, and the impact of overweight traffic on asphalt pavement overlay performance. The impact of dynamic loads on reflective fatigue cracking was distinguished at an early stage of the service period and eliminated after the 10-year analysis period, when the propagation of reflective cracking reached a specific level. On the other hand, the consideration of dynamic axle loads increased the impact of overweight truck traffic on pavement distresses, and pavement structures of major highways tend to be more sensitive to overweight traffic because of greater DLC excitement at higher operational speeds.
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JOHANNESSON, P. "Extrapolation of load histories and spectra." Fatigue Fracture of Engineering Materials and Structures 29, no. 3 (March 2006): 209–17. http://dx.doi.org/10.1111/j.1460-2695.2006.00982.x.

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Wang, Yiqiang, Yazhou Jia, Jian Qiu, and Guixiang Shen. "Load spectra of CNC machine tools." Quality and Reliability Engineering International 16, no. 3 (2000): 229–34. http://dx.doi.org/10.1002/1099-1638(200005/06)16:3<229::aid-qre314>3.0.co;2-u.

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Kliment, Linda K., and Kamran Rokhsaz. "Comparison of the Flight Loads Spectra of Two Business Jets." Fatigue of Aircraft Structures 2014, no. 6 (June 1, 2014): 5–20. http://dx.doi.org/10.1515/fas-2014-0001.

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Abstract Operational flight loads have been analyzed from two business jets, a Global 5000 and a Global Express XRS. It is shown that both airframes were subjected to nearly the same number of ground-air-ground cycles, even though the flight times were much different. Flights have been divided into various phases, and loads and turbulence data have been categorized by altitude bands within each phase. Cumulative occurrences of incremental vertical gust load factors have been compared and shown to be comparable for the two airframes. Maneuver load factors have been shown to spread over a wider range of values for the 5000 in every phase. This has been confirmed through comparison of combined loads with those from a CRJ100 and an ERJ-145XR. Derived gust velocities, obtained from the load factors are presented in the form of exceedance spectra. These results from both aircraft are shown to agree well
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Govardhan, T., Achintya Choudhury, and Deepak Paliwal. "Load Distribution in a Rolling Element Bearing under Dynamic Radial Load." Applied Mechanics and Materials 592-594 (July 2014): 1099–103. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1099.

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External load in a bearing is transferred from one race to another race through the rolling elements. In the present work, an investigation has been made to estimate the load on a rolling element in a bearing subjected to dynamic loading. The dynamic loading, in the present study, included harmonic and periodic loadings which are deterministic functions of time. The roller load is also investigated under random loading with known statistical values of mean and variance. Numerical values have been obtained for NJ204 bearing with known radial clearance. These results show the variation in the spectra obtained for different nature of external loadings. These results can be expected to satisfy the difference in theoretical and experimental spectra obtained by earlier researchers.
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HEULER, P., and H. KLATSCHKE. "Generation and use of standardised load spectra and load–time histories." International Journal of Fatigue 27, no. 8 (August 2005): 974–90. http://dx.doi.org/10.1016/j.ijfatigue.2004.09.012.

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Nagode, Marko, and Jernej Klemenc. "Modelling of load spectra containing clusters of less probable load cycles." International Journal of Fatigue 143 (February 2021): 106006. http://dx.doi.org/10.1016/j.ijfatigue.2020.106006.

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Rodzewicz, Miroslaw, and Dominik Glowacki. "Investigations into Load Spectra of UAVS Aircraft." Fatigue of Aircraft Structures 2013, no. 5 (August 21, 2014): 40–52. http://dx.doi.org/10.2478/fas-2013-0004.

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Abstract The paper contains a description of a novel approach to the load spectra estimation applied to UAVs. The authors have developed a number of tools in the LabVIEW environment enabling an in-depth analysis of flight-log data. One major achievement was the separation of the load spectra induced by steering and the load spectra induced by turbulence. The authors have shown a significant influence of both of the main load sources on the fatigue life of the UAV airframe, calculated based on the P-M hypothesis. This approach to fatigue testing of composite UAV airframes needs to take into account the rate of load variations as these may affect the fatigue life of tested structures. The paper presents several schemes of calculation algorithms and a number of well-illustrated examples of the tests and investigations results.
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Dissertations / Theses on the topic "Load spectra"

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Khosrovaneh, Abolhassan K. "Fatigue analysis and reconstruction of helicopter load spectra." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54213.

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Helicopter load histories applied to notched metal samples are taken as examples, and their fatigue lives are predicted by using a simplified version of the local strain approach. This simplified method requires an input load history in the form of the rain-flow matrix and places bounds on the fatigue life. A peak-valley reconstructed history is generated based on the standard spectrum Helix. A second history studied is a more irregular one based on actual flight data. lt is used to generate three reconstructed histories based on three principles: peak-valley, to-from, and rain-flow. Emphasis is given to the rain-flow reconstruction method, and different reconstruction methods based on rain-flow cycle counting are presented. Life predictions are presented for all of the above cases, and the comparison with test data and other considerations suggest that the most promising reconstruction approach is one based on rain-flow cycle counting. Finally, a method is presented which reconstructs a history with the same rain-flow cycles and also the same distribution of relative time increments between adjacent peaks and valleys. This reconstructed history gives the same fatigue life as the original history.
Ph. D.
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Zitounis, Vasilios. "Fatigue crack growth rates under variable amplitude load spectra containing tensile underloads." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/105.

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An extensive research program was performed to investigate the load interaction effect of the combined action of small amplitude high R ratio cycles and large amplitude low R ratio underloads on the crack growth of large cracks. The study was driven by the needs of the damage tolerance approach in the helicopter structures, which requires robust knowledge on the crack growth behaviour of the advance high strength alloys under the characteristic helicopter spectra loading. The study was conducted on three metallic alloys, Ti-10V-2Fe-3Al, Al8090 T852 and Al7010 T76351 using compact tension specimens (w=70mm, t=17mm). The potential drop technique was used for the measurements of the crack length. The crack opening loads were determined from the applied load versus crack opening mouth displacement curve using a curve fitting technique and crack opening displacement gauge. The experimental results show that cracks can grow faster than the life predictions with no load interaction effects under spectra containing tensile underloads. The acceleration effects are different depending on the number of the small cycles, the Kmax, the R ratio of the small cycles, the underload cycle and the material. Significant closure observations on the underloads and on the small cycles of variable amplitude loading spectra were made. Based on the test finding and on the studies of other researchers, it is suggested that the acceleration effects are mainly due to the reduction of crack opening point of the tensile underloads comparing with the Constant Amplitude Loading (CAL) data. An extensive evaluation of the ability of FASTRAN model to predict the fatigue lives under the tested loading spectra was carried out. The evaluation focuses on the influence of the constraint factor a and the ∆Keff curve inputs on the predictions. The model produces very good and consistent predictions for the three alloys, when the inputs represent adequately the actual fatigue mechanism. The model predicts the measured acceleration effects by reducing the closure level of the underloads.
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Lee, Hongchul. "Advanced aircraft service life monitoring method via flight-by-flight load spectra." Diss., Online access via UMI:, 2009.

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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2009.
Includes bibliographical references.
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Walter, Richard W. "Study of statistical variations of load spectra and material properties on aircraft fatigue life." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/24056.

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Shan, Martin [Verfasser]. "Load Reducing Control for Wind Turbines: Load Estimation and Higher Level Controller Tuning based on Disturbance Spectra and Linear Models / Martin Shan." Kassel : Universitätsbibliothek Kassel, 2017. http://d-nb.info/1154972496/34.

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Entesar, Abdullah Ali. "Statistical analysis of truck loading on Swedish highways." Thesis, KTH, Transportvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-45980.

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Vehicle over loading, or single axle over loading, is one of the major causes of pavement deterioration. Trafik Verket (TV), the Swedish Transport Administration, recognized that the current process for estimating traffic volume should be reevaluated, and if possible improved. This degree project uses data from the Bridge Weigh in Motion (BWIM) system to study the actual loads applied to Swedish highways. The axle load spectrum is plotted with the conventional frequency distribution plots, and with a new cumulative distribution approach. The paper introduces the maximum allowable potential vehicle weight MAPVW concept, and uses this visual technique to identify overloads for different vehicle geometries. The paper concludes that for 5 and 6 axle trucks the triple axle is frequently overloaded, while for longer trucks one of the dual axles is often over loaded. The highest over loads tend to be on the driving axle, suggesting incorrect loading procedures.
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Fontenele, Heliana Barbosa. "Representação do tráfego de veículos rodoviários de carga através de espectros de carga por eixo e seu efeito no desempenho dos pavimentos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18143/tde-12032012-111950/.

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A caracterização das cargas do tráfego é de grande importância para o dimensionamento de pavimentos, bem como para a quantificação do desempenho para fins de gerência de pavimentos. A utilização de abordagens empíricas para determinar os efeitos das cargas do tráfego nas estruturas de pavimentos, datadas dos anos 1960, apresentam sérias limitações, pois seus resultados são válidos somente para os mesmos, ou muito similares, fatores intervenientes que prevaleciam quando do seu desenvolvimento. Os fatores relativos às solicitações do tráfego e às características dos veículos (tipo de eixo, tipo de rodagem, pressão de enchimento dos pneus e tipo de suspensão) são bem diferentes, atualmente, daquelas existentes há 50 anos. Tendo em vista que os modelos de desempenho são importantes ferramentas dos sistemas de gerência de pavimentos (SGP) para prever a evolução da condição ao longo do tempo e/ou tráfego acumulado e, portanto, dependentes de uma consistente caracterização do tráfego, o objetivo desta pesquisa foi analisar os efeitos da caracterização do tráfego sobre o desempenho dos pavimentos, a partir da geração de modelos estatísticos baseados no conceito proposto pelo método da AASHTO 2002, de espectros de carga por eixo dos veículos comerciais de carga, comparando-os com o conceito de equivalência de carga, desenvolvido a partir do AASHO Road Test na década de 1950. Dados de pesagens realizadas no ano de 2008 no Posto de Pesagem de Veículos da SP-160 Rodovia dos Imigrantes, km 28, pista Sul, foram utilizados para o desenvolvimento dos espectros de carga e posterior modelagem. Testes estatísticos e práticos foram realizados para determinar a variabilidade mensal dos Fatores de Veículos (FV) em relação ao valor médio do ano de 2008. Apesar da análise estatística com a aplicação do teste Kolmogorov-Smirnov (K-S) ter apresentado diferenças significativas entre os espectros mensais e anuais, a variação observada nos fatores de tráfego não resultou em diferenças práticas na espessura final do pavimento. Os modelos estatísticos foram desenvolvidos separadamente para cada classe de veículo e de eixos que o compunha, tendo sido usadas distribuições de probabilidade Log-normal e Weibull para modelar os espectros de carga. Os parâmetros dos modelos foram obtidos através do método dos mínimos quadrados, complementado com a realização de testes K-S e Qui-quadrado, destacando-se a obtenção de coeficientes de determinação (R2) superiores a 0,90. A comparação entre os resultados previstos pelos modelos e os dados originais, feita tanto pela abordagem empírica como empírico-mecanística, com uso dos programas computacionais ELSYM5 e MEPDG, evidencia o modelo Weibull como o mais indicado para aplicação em rodovias brasileiras com características de tráfego semelhantes às da Rodovia dos Imigrantes.
The characterization of traffic loads is of great importance for pavement design, as well as for the measurement of performance in a pavement management system. The use of empirical approaches to determine the effects of traffic load on pavement structures, dating from the 1960\'s, presents serious limitations, since its results are just valid for the same or very similar intervening factors that prevailed at the time of its development. The traffic load factors and vehicle characteristics (axle type, tire type, tire inflation pressure, and suspension type) are quite different today from those existing 50 years ago. Given that the performance models are important tools of pavement management systems (PMS) to predict the evolution of pavement condition over time and/or accumulated traffic and therefore dependent on a consistent characterization of the traffic, the objective of this research was to analyze the effects of traffic characteristics on pavement performance through the generation of statistical models based on the concept proposed by the AASHTO 2002 method, axle load spectra of commercial vehicles, comparing them with the concept of load equivalence factor, developed through the AASHO Road Test in the 1950s. Data collected in 2008 in a weighing station located on Immigrant Highway - SP-160, km 28, southern runway, were used for the development of load spectra and subsequent modeling. Practical and statistical tests were performed to determine the variability of monthly vehicle-factors (FV) to the mean value for the year 2008. Despite the statistical analysis, performed by applying the Kolmogorov-Smirnov (KS) test, have shown significant differences between the monthly and annual spectra variation, there were not practical differences in the final thickness of the pavement associated to changes in vehicle-factors. Statistical models were developed for each vehicle class and for its axles, having been used Log-normal and Weibull probability distributions to model the load spectra. The model parameters were obtained from the method of least squares, complemented by the KS and chi-square tests, being important to mention that the coefficients of determination (R2) were greater than 0.90. The comparison between the results predicted by the models and the original data, made either by empirical and empiricalmechanistic approaches, with use of computer programs ELSYM5 and MEPDG, shows that the Weibull model is the most suitable for application in Brazilian highways with similar traffic characteristics to the Immigrants Highway.
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Frankhouser, Andrew. "Characterization of Ohio Traffic Data for Integration into the Mechanistic-Empirical Pavement Design." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1365980149.

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Elsässer, Robert. "Spectral methods for efficient load balancing strategies." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965647145.

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Reytier, Thomas. "Modelling fatigue spectra of aircraft structure under gust loads." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1614/.

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Cette thèse est consacrée à l'analyse de fatigue et de tolérance aux dommages des structures d'avions soumis aux rafales de vent. L'analyse de fatigue et de tolérance aux dommages est un enjeu essentiel dans la conception des structures d'avions. Elle permet de définir un programme d'inspection de la structure afin d'assurer sa sécurité tout au long de la vie de l'avion. La première partie passe en revue l'état de l'art dans les différents domaines impliqués dans le processus global d'analyse de fatigue des structures d'avions soumis aux rafales de vent: la modélisation de la turbulence atmosphérique, le calcul des charges et des contraintes à l'aide d'analyses par éléments finis, la construction du spectre de fatigue et enfin, l'analyse de fatigue et de tolérance aux dommages. La deuxième partie présente le processus complet actuellement implémenté au sein d'Airbus. Les points forts et les points faibles de ce processus sont d'identifiés et permettent de dégager des axes d'amélioration. A partir du modèle de turbulence continue basé sur la densité spectrale de puissance (DSP) de Von Karman, les contraintes calculées sont insérées selon des statistiques établies par des mesures envol dans le spectre de fatigue pour former une séquence de cycles de contraintes. Les données d'entrée pour l'analyse de fatigue et tolérance aux dommages sont obtenues à partir de la définition des différents profils de mission, des valeurs de contraintes unitaires, de la réponse dynamique de la structure et des statistiques de turbulence. Dans la troisième partie, une nouvelle méthodologie est présentée afin d'obtenir des séquences temporelles des contraintes dues à la turbulence de manière précise et efficace. Cette méthode s'appuie sur de nouveaux résultats permettant de générer des signaux temporels corrélés à partir des DSP. Tout d'abord, les DSP des différentes composantes des contraintes sont directement obtenues à l'aide d'une analyse par éléments finis à partir de la DSP de Von Karman. Puis, les séquences temporelles corrélées de ces contraintes sont générées et sont ensuite distribuées dans le spectre de fatigue selon la loi statistique de l'intensité de la turbulence atmosphérique. Ce nouveau processus permet d'améliorer le calcul des contraintes et la génération du spectre de fatigue. Il remplace les statistiques de turbulence par des statistiques de franchissement de niveaux de contraintes raisonnablement conservatives définies par une formule analytique. De plus, le temps de livraison des données d'entrée pour l'analyse de fatigue et tolérance aux dommages est significativement réduit. Les résultats présentés, issus de l'analyse de fatigue et de tolérance aux dommages, permettent de souligner la qualité des améliorations apportées à la fois en termes de précision et de durée du processus
This thesis is dedicated to the fatigue and damage tolerance analysis of the aircraft structures under gust loads. The fatigue and damage tolerance analysis is a significant issue in the aircraft structure design. It aims at defining the inspection program of the aircraft structure in order to ensure its safety through its entire life. The first part reviews the state-of-the-art in the various involved topics for the global process for fatigue analysis of aircraft structure under gust loads: the atmospheric turbulence modelling, the load and stress computation by a finite element analysis, the generation of the fatigue spectrum and at the end, the fatigue and damage tolerance analysis. The second part presents the whole process currently implemented at Airbus. The main strengths and weaknesses are pointed out and this en-ables the identification of several improvement axes. From the continuous turbulence model based on the Von Karman Power Spectral Density(PSD), the computed stresses are included according to statistics established from in-flight measurements in the fatigue spectrum in order to build a stress cycle sequence. The input data for the fatigue and damage tolerance analysis are obtained from the definition of the various fatigue mission profiles, the unitary stress values, the dynamic response of the structure and the turbulence statistics. In the third part,a new methodology is presented in order to obtaine efficiently and accurately the temporal stress sequences due to the atmospheric turbulence. This method relies on new results enabling the generation of correlated time signals from the PSD functions. First, the PSD of the various stress components are directly obtained from the Von Karman PSD via a finite element analysis. Then, the correlated temporal stress sequences are generated and distributed in the fatigue spectrum according to the turbulence intensity statistical law. This new process enables the improvement of the stress computation and the fatigue spectrum generation. It replaces the turbulence statistics by stress exceedance statistics which are defined by an analytical formula in a reasonably conservative way. In addition, the lead time to build the input data for the fatigue and damage tolerance analysis is significantly reduced. Results from the fatigue and damage tolerance analysis are presented in order to highlight the quality of the improved processes both in terms of accuracy and lead time
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Books on the topic "Load spectra"

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Spahl, Robert. Safety tests for components of vehicles using load spectra. Aachen: Shaker, 1996.

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Noback, R. The generation of equal probability design load conditions, using P.S.D.-techniques. Amsterdam: National Aerospace Laboratory NLR, 1985.

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F, Newell James, and United States. National Aeronautics and Space Administration., eds. Composite load spectra for select space propulsion structural components: Final report. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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W, Ho H., Kurth R. E, and United States. National Aeronautics and Space Administration., eds. Composite load spectra for select space propulsion structural components: Final report. [Washington, DC: National Aeronautics and Space Administration, 1991.

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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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Walter, Richard W. Study of statistical variations of load spectra and material properties on aircraft fatigue life. Monterey, Calif: Naval Postgraduate School, 1992.

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Mason, Patrick H. Identification of random loads impinging on the RAH-66 Comanche Helicopter empennage using spectral analysis. Monterey, Calif: Naval Postgraduate School, 1998.

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Composite load spectra for select space propulsion structural components: Annual report. [Washington, DC: National Aeronautics and Space Administration, 1986.

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Composite load spectra for select space propulsion structural components: Annual report. [Washington, DC: National Aeronautics and Space Administration, 1986.

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Improving traffic characterization to enhance pavement design and performance: Load spectra development. [Olympia, Wash.]: Washington State Dept. of Transportation, 2005.

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Book chapters on the topic "Load spectra"

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Köhler, Michael, Sven Jenne, Kurt Pötter, and Harald Zenner. "Load Spectra and Matrices." In Load Assumption for Fatigue Design of Structures and Components, 55–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-642-55248-9_4.

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Broek, David. "Load spectra and stress histories." In The Practical Use of Fracture Mechanics, 168–207. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2558-8_6.

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Köhler, Michael, Sven Jenne, Kurt Pötter, and Harald Zenner. "Design and Dimensioning Load Spectra." In Load Assumption for Fatigue Design of Structures and Components, 131–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-642-55248-9_10.

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Hrudičková, M., and Z. Folta. "Processing of Automobile Gearbox Load Spectra." In Lecture Notes in Mechanical Engineering, 335–41. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05203-8_46.

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Teixeira, Rui, Maria Nogal, and Alan O’Connor. "On the Calculation of Offshore Wind Turbine Load Spectra for Fatigue Design." In Structural Integrity, 383–90. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-13980-3_49.

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Maksimovic, Katarina, Strain Posavljak, Mirko Maksimovic, Ivana Vasovic Maksimovic, and Martina Balac. "Total Fatigue Life Estimation of Aircraft Structural Components Under General Load Spectra." In Experimental and Computational Investigations in Engineering, 394–412. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-58362-0_23.

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Timm, David, Kendra Peters, and Rod Turochy. "Effects of axle load spectra shifts on highway infrastructure damage and cost." In International Conference on Heavy Vehicles HVParis 2008, 571–78. Hoboken, NJ, USA: John Wiley & Sons, Inc, 2013. http://dx.doi.org/10.1002/9781118623305.ch46.

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Zhang, Jie, Sven Trogh, Wim De Waele, and Stijn Hertelé. "Fatigue Crack Propagation in HSLA Steel Specimens Subjected to Unordered and Ordered Load Spectra." In Lecture Notes in Mechanical Engineering, 718–27. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8331-1_56.

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Rucconi, Valerio, Letizia De Maria, Daniele Bartalesi, Bau Valecillos, Simone Garatti, and Sergio Bittanti. "No-Load Transformers: Vibration Spectra Analysis by Deep Learning Methods for Loose Windings Detection." In Lecture Notes in Electrical Engineering, 251–57. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-08136-1_39.

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Huang, Xiaoping, Honggan Yu, and Dimitrios G. Pavlou. "The Effect of Loading Sequence on Fatigue Crack Growth of a Ship Detail Under Different Load Spectra." In Lecture Notes in Civil Engineering, 442–53. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-4672-3_28.

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Conference papers on the topic "Load spectra"

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Zhao, Jiaxi, Weixing Chen, Sean Keane, Jenny Been, and Greg Van Boven. "Development and Validation of Load-Interaction Based Models for Crack Growth Prediction." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33325.

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This investigation primarily focused on the validation of the software being developed for crack growth and remaining life prediction using SCADA data. A total of nine pressure spectra, four for oil pipelines and five for gas pipelines, have been collected and used as inputs for the software. It was found that these spectra could be categorized as the underload-, the meanload- and the overload-dominant spectra; each of them have shown different effects on crack growth: the underload spectra, typical of pressure fluctuations at the discharging sites, are most susceptible to crack growth because of load interactions between the minor pressure fluctuations and the unload cycles; while the overload spectra, often found at the suction site, have exhibited retarded crack growth due to the retardation effects caused by overloading. The relative severity of the load interactions in terms of crack growth rate for a given spectrum was quantified using a parameter termed as the Spectrum Factor. A Spectrum Factor greater than one indicates the enhanced crack growth rate by load interactions, such as the case where unloading is frequently present in the pressure spectra, while a Spectrum Factor lower than one may be associated with a retarded crack growth, which can be seen in pressure spectra with predominant overloading events. The predictions made by the models being developed were also compared with those made by the rainflow counting method. The software allows for the SCADA/pressure fluctuation data, in excel spreadsheet format, to be directly analyzed producing a projected remaining life of the pipeline based on the past pressure fluctuations and the assumed future pressure fluctuations.
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VA, P. "ACQUIRING TAIL LOAD SPECTRA FROM IN-FLIGHT MEASUREMENTS." In 34th Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1993. http://dx.doi.org/10.2514/6.1993-1607.

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Mattioli, Matteo, Michele Drago, Federico Quondamatteo, and Roberto Bruschi. "Load History for SSFU Under Multimodal Wave Spectra." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10803.

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This paper presents results from an ongoing development project which aims at increasing the knowledge for the estimation of extremes conditions and fatigue assessment of structural element (i.e. topside) of Ship Shaped Floating Units (SSFU) in a complex environment-load conditions. The method can be extended for the calculation of total bending moment to connections and hull-girder system. In some world geographical context, such as those of West Africa and Offshore Brazil, the environmental conditions are characterized by co-existence of waves and swells propagating in different directions. In these conditions load history for SSFU are strictly linked to comprehension knowledge of site specific environment. Loads pertain to various frequency ranges, for instance the long-period response of a morning, quasi-static response to swell, dynamic response to shore-crested sea and structural resonance of flexible components as flares etc. This paper aims at developing a new method for establishing load history at site in case of metocean climate including combination of several (up to 3 or 4) sea state components, such as those of main swell, secondary swell and wind sea. The method is applicable to both extreme conditions and fatigue assessment as results of a “combined-event approach”. The results are compared and discussed. They show that the use of different approaches, long and a short term analysis with deterministic and probabilistic computation of vessel heading, provide a reasonably conservative estimate of the vessel responses. Differences from the conventional method, i.e. unimodal spectrum and equivalent sea state, are also presented.
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O’Leary, Michael, and William Godfrey. "Seismic Response Analysis and Design for Concrete Nuclear Structures: A Comparative Study of the Time History, Response Spectrum, and Equivalent Static Load Methods." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63314.

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A partially buried fixed-base finite element model of a typical safety-related nuclear structure is analyzed for earthquake loads by the time history method, the response spectrum method, and the equivalent static load method. The spectra-consistent artificial time histories are generated with seed time histories in accordance with Standard Review Plan 3.7.1: Seismic Design Parameters [1] with target spectra based on Regulatory Guide 1.60: Design Response Spectra for Seismic Design of Nuclear Power Plants [2]. The response spectrum analyses are performed with the same target spectra used in generating the artificial time histories. The equivalent static loads are based on the nodal zero period accelerations from the fixed-base time history analyses. The seismic responses in a column in the structure are combined using algebraic sum, square root of the sum of the squares (SRSS), and the 100-40-40 rule in accordance with Regulatory Guide 1.92: Combining modal responses and spatial components in seismic response analysis [3]. The equivalent static load method is applied according to ASCE 4-15: Seismic Analysis of Safety-Related Nuclear Structures [4]. The resulting design forces and required reinforcement for a column in the structure are compared for each method along with the corresponding computational demand.
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Scavuzzo, Rudolph J., George D. Hill, and Peter Saxe. "The “Spectrum Dip”: Dynamic Interaction of System Components." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26757.

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In the early 1960s, many full sized surface combatants, submarines and structural models were tested with underwater explosive in order to evaluate the shock load to the ship and internal equipment and structures. Initially, shock spectra were calculated from base motion measurements of internal equipment and components. Attempts were made to envelop these spectra to develop shock design spectra inputs. At that time, earthquake engineers were using this enveloping method to develop design procedures from ground motion measurements to protect structures from earthquakes. However, for the measurements on ships, this procedure resulted in calculated loads that would have caused catastrophic failure of the equipment; yet the equipment had not failed on the ship tests. As a result, the data was reanalyzed over a period of over a year. It was concluded that the dynamic interaction of each component or structure reduced the measured spectral motion at the fixed-base frequencies of the structure by about an order of magnitude. In many cases, there was a dip in the shock spectra at the fixed-base frequencies: the “spectrum dip” phenomenon. This reanalysis led to shock spectra design curves for navy ships. This paper will present a review of an experimental study and an analytical model to explain the effect of dynamic interaction on the shock or response spectrum. In addition, a practical example of interaction of four single mass dynamic systems mounted on a realistic deck and subjected to a high impact shock input was studied by the authors.
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Hay, N. C., and C. J. Dodds. "Vehicle Load Histories: The Duality of Vibration and Fatigue Spectra." In Passenger Car Meeting & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1987. http://dx.doi.org/10.4271/871938.

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Bordelon, A. C., J. E. Hiller, J. R. Roesler, and V. G. Cervantes. "Investigation of ESALs versus Load Spectra for Rigid Pavement Design." In Airfield and Highway Pavements 2015. Reston, VA: American Society of Civil Engineers, 2015. http://dx.doi.org/10.1061/9780784479216.044.

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Storgärds, Erik, Kjell Simonsson, Sören Sjöström, David Gustafsson, and Tomas Månsson. "Modelling of Crack Growth With Dwell Time for Aero Engine Spectra Loadings in a Ni-Based Superalloy." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42701.

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Testing and simulation of aero engine spectra with dwell times are reported in this paper. The modelling concept used is built on LEFM and provides a history dependent evolution description of dwell damage and its interaction with cyclic load. The simulations have been carried out for three spectra, 1) cyclic loads, 2) combined sustained load and cyclic loads and 3) slow load ramps and cyclic loads, all for surface cracks at 550°C for Inconel 718. All simulations show reasonable good agreement with experimental results. Prediction of multiple tests of several batches is also provided to show statistical scatter.
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Kuwar, Virendra S., Omkar Thorat, Nikhil Rajendra Bakal, Omkar Prakash Joshi, Prashant R. Pawar, Vikram V. Shinde, Mohan Sutar, et al. "Development of Methodology for Accelerated Validation of Axle Components in Relation to Static Load Capacity." In Symposium on International Automotive Technology. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2024. http://dx.doi.org/10.4271/2024-26-0373.

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<div class="section abstract"><div class="htmlview paragraph">The Indian automotive industry is striving towards more safe and durable vehicles. A need was felt to study the effect of changes in axle static loads on fatigue life of the axle components. Also, there was a need to develop generic test method, as there are no test standards or generic methods available in public domain for fatigue testing of commercial vehicle axles. The study was carried out to check direct effect of change in axle loads on various connections on axle, effect of suspension configuration and force distribution, Vehicle dynamics, etc.</div><div class="htmlview paragraph">In this paper, an India specific generic load spectra was evaluated for accelerated laboratory validation. Paper discusses the methodology as; study of heavy commercial vehicle systems, road load data collection on identified test vehicles w.r.t. test matrix finalized, India specific test loads and load spectra development, normalization of axle load spectra w.r.t to static axle weights and arriving at test guidelines. Comprehensive experiments and load measurements were carried out on test vehicles to arrive at a generic test methodology and test cycles. The derived test specifications were correlated with current industry practices and the actual in-lab experiments were conducted.</div></div>
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Liu, Xu, Yan-Hui Zhang, and Bin Wang. "Fatigue Performance of Welded Joints Under Variable Amplitude Loading Spectra." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93073.

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Abstract Offshore pipelines are generally subjected to variable amplitude (VA) loading in service due to waves or ocean currents. Welded joints often represent the most critical locations for fatigue cracking. Use of the current fatigue design guidance, for example, BS 7608, to assess fatigue performance of the welded joints in such structure may lead to inaccurate estimates depending on the nature of the VA loading spectrum. Further studies on the effect of VA loading spectra on fatigue performance of welded joints are needed. In this research, both uniaxial and 3-point bending fatigue tests were performed on non-load carrying fillet welded plates under VA loading spectra to investigate the effects of mean stress and the type of VA loading spectra. The influence of plate thickness was also investigated. Test results suggest that the spectrum with a high constant maximum tensile stress (cycling-down) could significantly degrade fatigue performance of welded joints, with the damage parameter D only at around 0.5. The severity of this type of loading spectrum depends on the mean stress level and the plate thickness. An analytical model has been developed to predict fatigue crack propagation (FCP) by considering the interaction of stresses in the loading spectrum. The model considers the impact of the mean stress generated by the preceding load on FCP in the subsequent cycles. FCP predicted by the model shows a good agreement with the experimental data.
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Reports on the topic "Load spectra"

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Bao, Jieyi, Xiaoqiang Hu, Cheng Peng, Yi Jiang, Shuo Li, and 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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Chen. PR-378-083601-R01 Effect of Pressure Fluctuations on Growth Rate of Near-Neutral pH SCC. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), October 2013. http://dx.doi.org/10.55274/r0010798.

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This report summarizes the work completed in Year One of the three-year project: PRCI SCC-2-12 Effect of Pressure Fluctuations on Growth Rate of Near-Neutral pH SCC. The investigation in Year One has been primarily focused on the validation of the software being developed for crack growth and remaining life prediction using SCADA Data. A total of 9 pressure spectra, 4 for oil pipelines and 5 for gas pipelines, have been collected and used as inputs for the software. It was found that a pressure spectrum can be quantified using a parameter termed as Spectra Factor to represent the severity of load/pressure interactions in terms of crack growth rate. A spectra factor higher than one indicates the enhanced crack growth rate by load interactions, such as the case where unloads are frequently present in the pressure spectra, while a spectra factor lower than one may be associated with a retarded crack growth, which can be seen in pressure spectra with predominant overloading events. The oil pipelines are characterized with more frequent and larger pressure fluctuations, and crack growth is directly caused by these cycles. The gas pipelines are characterized with minor cycles with high stress ratio and the subsequent underloading cycles with low stress ratios, and crack growth rate can be enhanced by a factor 10 under the combined minor-underload pressure fluctuation cyclic loading scenarios. The software allows the SCADA/pressure fluctuation data with Excel spreadsheet format to be directly analyzed producing a projected remaining life of the pipeline based on the past pressure fluctuations and assumed future pressure fluctuations.
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Jiang, Yi, Shuo Li, and Tommy Nantung. Analysis and Determination of Axle Load Spectra and Traffic Input for the Mechanistic-Empirical Pavement Design Guide. West Lafayette, Indiana: Purdue University, 2008. http://dx.doi.org/10.5703/1288284314325.

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Hendrickson, B., and R. Leland. Multidimensional spectral load balancing. Office of Scientific and Technical Information (OSTI), January 1993. http://dx.doi.org/10.2172/6691328.

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Zand, Benjamin. PR-218-104509-R01 Field Validation of Surface Loading Stress Calculations for Buried Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), August 2013. http://dx.doi.org/10.55274/r0010547.

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The objective for this two phase project was to validate surface loading criterion for pipelines with shallow burial. This is the report of the first phase of this project which focused on field measurements of the stress in shallow buried pipe while it is being crossed by heavy equipment. During the second phase, this data will be compared with the predictions of the most prevalent models currently used for surface load stress analysis for pipelines with shallow cover. The objective of the two phase study is to have a validated model for surface loading of shallow buried pipe. In the phase I, Kiefner and Associates, Inc. instrumented three buried pipe segments at the Spectra Energy Berne Station in Southeastern Ohio. The station was PRCI approved. The line was instrumented with strain gauges in order to make direct measurements of the stress in the pipeline as heavy equipment crosses over the pipeline. The data generated in this first phase and, if necessary, additional data from a second phase will be compared with the current Spangler, Iowa and CEPA models used for surface load stress analysis during the second phase.
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RECONSTRUCTION OF FATIGUE DAMAGE STATE OF IN-SERVICE STEEL BRIDGES WITHOUT LOAD INFORMATION. The Hong Kong Institute of Steel Construction, August 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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POWER FLOW ANALYSIS OF BRIDGE U-RIB STIFFENED PLATES BASED ON THE CONCEPT OF STRUCTURAL INTENSITY. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.061.

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Due to its advantages of good mechanical properties, simple appearance and strong adaptability, the steel box girder is being widely utilized in urban bridges. The noise radiated by steel box girders subjected to vehicle impacts has the characteristics of wide-spectrum, high-magnitude and control difficulty. U-rib stiffened roof, as a part of the steel box girder, directly bears the input load, which is the basis of studying the vibration of the steel box girder. Currently, the investigation on the vibro-acoustic performance of U-rib plates is very limited. With this regard, this paper introduces the concept of Structural Intensity (SI). The SI vector is calculated by the Finite Element (FE) method. The power flow is visualized by the self-programming post-processing code. The global and local vibration energy transmission characters of a U-rib stiffened plate under a harmonic nodal force are analyzed. Further, the influence of plate thickness is investigated. The optimum design is carried out based on the engineering standard dimensions. The research results indicate that increasing the thickness ratio of the U-rib to the baseplate is beneficial to reducing the vibration.
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