Development of method for assessing the quality of simulations of dynamic behavior of railway vehicles

Eksperimentalna ispitivanja železničkih vozila predstavljaju najpouzdaniji način za utvrđivanje njihovih svojstava i presudni kriterijum za odobrenje njihove eksploatacije. Međutim, eksperimentalna ispitivanja su obimna, dugotrajna i skupa, pa su alternativni metodi, koji se koriste tokom projektovanja vozila, od najvećeg interesa. U tom cilju se razvijaju numeričke simulacije kretanja železničkih vozila, koje na osnovu matematičkog modela vozila i koloseka omogućavaju izračunavanja dinamičkih veličina u vremenskom i frekventnom domenu. Cilj ovog istraživanja je definisanje metodologije za validaciju modela dinamičkog ponašanja železničkog vozila. Pridržavajući se preporuke trenutno važećih standarda za eksperimentalna ispitivanja dinamičkog ponašanja železničkog vozila (UIC 518 i EN14363), a na osnovu dosadašnjih istraživanja verifikacije i validacije modela železničkih vozila i numeričkih modela uopšte, predložena je nova metrika za ocenu validnosti numeričkog modela železničkog vozila. Predložena validaciona metrika ocenu o slaganju rezultata dobijenih simulacijom i eksperimentalnim ispitivanjem formira na osnovu poređenja kumulativnih funkcija verovatnoća izabranih veličina za poređenje. U okviru disertacije definisana je validaciona hijerarhija, validaciona metrika, veličine za poređenje i granične vrednosti validacione ocene za prihvatanje validnosti numeričkog modela. Predložena metodologija validacije primenjena je na model železničkog vozila za prevoz rude gvožđa tipa „Fanoo 040“. Rezultati validacije modela dobijeni metodologijom predloženom u ovoj disertaciji dati su uporedo rezultatima dobijenim metodologijom validacije predložene u okviru projekta “DYNOTrain”. Novopredložena validaciona metrika omogućava da se izvrši objektivna ocena slaganja rezultata simulacije i eksperimenta za svaku od izabranih veličina za poređenje. Analizom dobijenih rezultata pokazano je da novopredložena metodologija validacije postavlja strožije uslove validacije u odnosu na metodologiju validacije prikazane u okviru projekta “DYNOTrain”. Validacija modela izvršena korišćenjem novopredložene metodologije daje mogućnost da se smanji obim eksperimentalnih ispitivanja.Experimental investigations of railway vehicles represent the most reliable way to determine their properties and decisive criterion for the approval of their exploitation. However, experimental tests are extensive, time-consuming and expensive, so alternative methods, which are used in the design of vehicles, are of the greatest interest. With this goal are developed numerical simulations of the dynamic behavior of railway vehicles that, on the basis of mathematical models, allow calculation of dynamic values in the time and frequency domain. The aim of this study is to define a methodology for the validation of models od railway vehicles dynamics. By adhering to the recommendations of actual standards for experimental investigation of the dynamic behavior of railway vehicles (UIC 518 and EN14363), and based on previous research of verification and validation of railway vehicles model and numerical models in general, a new validation metrics is proposed for assessment of the numerical models of railway vehicles. The proposed validation metrics assesses the agreement between the results obtained by simulation and experimental testing on the basis of comparison between cumulative probability functions of the assessment quantities. In this dissertation is defined the validation hierarchy, validation metrics, assesment quantities and validation limits for estimation of acceptance of a numerical model of a railway vehicle. The proposed methodology was applied to the validation of a model of railway wagon of type "Fanno 040", which is used for transport of iron ore. The results obtained with the methodology for model validation proposed in this thesis are compared to the results obtained by the methodology proposed in the international project "DYNOTrain". The newly proposed validation metrics enabled an objective assessment of the agreement between simulation and experimental results for each of the selected assesment quantities. The obtained results showed that the newly proposed methodology for validation of model of railway vehicles represents a more severe estimation of agreement between the simulation and experimental results than the metrics proposed in the project "DYNOTrain". Model validation performed using the newly proposed methodology provides an opportunity for reduction of the volume of expensive experimental tests

CAVITATION RESISTANCE OF THE MATERIAL PA 3200 GF PRODUCED BY SELECTIVE LASER SINTERING

The present study focuses on the results of cavitation resistance research of samples obtained by the Selective Laser Sintering technology. The material used was Polyamide powder PA 3200 GF reinforced with glass fibers. The laser-sintered samples were produced from 100% new and recycled powder mixed with 70% of new powder. The samples were tested under cavitation conditions using an ultrasonic vibration method with a stationary sample according to the ASTM G-32 standard. Examination of the morphology of cavitation damage was investigated by scanning electron microscopy. The change in mass loss during different cavitation times was measured on the tested samples. The main objective of the research was to determine the validity application of the tested material in cavitation condition

EFFECT OF SECTION THICKNESS ON CAVITATION BEHAVIOUR OF SELECTIVE LASER SINTERED POLYAMIDE 12

The present study focuses the cavitation resistance results of samples obtained by the Selective Laser Sintering technology. All samples were made from Nylon 12 – Polyamide 12 powder, also known as PA2200 in the industry, produced by EOS GmbH. The powder used for building the samples represented a mixture of 50% new powder and 50% recycled powder. Samples with different section thicknesses (0.4mm; 0.8mm and 1.0mm) were subjected to the ultrasonically induced cavitation test method to investigate the effect of geometry on their cavitation behaviour. The change in mass loss during different cavitation times was measured on the tested samples. The morphology of cavitation damage was characterized using Scanning Electron Microscopy (SEM). The results obtained in this paper have shown that section thickness of the samples has a significant influence on the cavitation resistance, with the highest cavitation resistance obtained for the samples a thickness of 0.4mm

Development of method for assessing the quality of simulations of dynamic behavior of railway vehicles

Eksperimentalna ispitivanja železničkih vozila predstavljaju najpouzdaniji način za utvrđivanje njihovih svojstava i presudni kriterijum za odobrenje njihove eksploatacije. Međutim, eksperimentalna ispitivanja su obimna, dugotrajna i skupa, pa su alternativni metodi, koji se koriste tokom projektovanja vozila, od najvećeg interesa. U tom cilju se razvijaju numeričke simulacije kretanja železničkih vozila, koje na osnovu matematičkog modela vozila i koloseka omogućavaju izračunavanja dinamičkih veličina u vremenskom i frekventnom domenu. Cilj ovog istraživanja je definisanje metodologije za validaciju modela dinamičkog ponašanja železničkog vozila. Pridržavajući se preporuke trenutno važećih standarda za eksperimentalna ispitivanja dinamičkog ponašanja železničkog vozila (UIC 518 i EN14363), a na osnovu dosadašnjih istraživanja verifikacije i validacije modela železničkih vozila i numeričkih modela uopšte, predložena je nova metrika za ocenu validnosti numeričkog modela železničkog vozila. Predložena validaciona metrika ocenu o slaganju rezultata dobijenih simulacijom i eksperimentalnim ispitivanjem formira na osnovu poređenja kumulativnih funkcija verovatnoća izabranih veličina za poređenje. U okviru disertacije definisana je validaciona hijerarhija, validaciona metrika, veličine za poređenje i granične vrednosti validacione ocene za prihvatanje validnosti numeričkog modela. Predložena metodologija validacije primenjena je na model železničkog vozila za prevoz rude gvožđa tipa „Fanoo 040“. Rezultati validacije modela dobijeni metodologijom predloženom u ovoj disertaciji dati su uporedo rezultatima dobijenim metodologijom validacije predložene u okviru projekta “DYNOTrain”. Novopredložena validaciona metrika omogućava da se izvrši objektivna ocena slaganja rezultata simulacije i eksperimenta za svaku od izabranih veličina za poređenje. Analizom dobijenih rezultata pokazano je da novopredložena metodologija validacije postavlja strožije uslove validacije u odnosu na metodologiju validacije prikazane u okviru projekta “DYNOTrain”. Validacija modela izvršena korišćenjem novopredložene metodologije daje mogućnost da se smanji obim eksperimentalnih ispitivanja.Experimental investigations of railway vehicles represent the most reliable way to determine their properties and decisive criterion for the approval of their exploitation. However, experimental tests are extensive, time-consuming and expensive, so alternative methods, which are used in the design of vehicles, are of the greatest interest. With this goal are developed numerical simulations of the dynamic behavior of railway vehicles that, on the basis of mathematical models, allow calculation of dynamic values in the time and frequency domain. The aim of this study is to define a methodology for the validation of models od railway vehicles dynamics. By adhering to the recommendations of actual standards for experimental investigation of the dynamic behavior of railway vehicles (UIC 518 and EN14363), and based on previous research of verification and validation of railway vehicles model and numerical models in general, a new validation metrics is proposed for assessment of the numerical models of railway vehicles. The proposed validation metrics assesses the agreement between the results obtained by simulation and experimental testing on the basis of comparison between cumulative probability functions of the assessment quantities. In this dissertation is defined the validation hierarchy, validation metrics, assesment quantities and validation limits for estimation of acceptance of a numerical model of a railway vehicle. The proposed methodology was applied to the validation of a model of railway wagon of type "Fanno 040", which is used for transport of iron ore. The results obtained with the methodology for model validation proposed in this thesis are compared to the results obtained by the methodology proposed in the international project "DYNOTrain". The newly proposed validation metrics enabled an objective assessment of the agreement between simulation and experimental results for each of the selected assesment quantities. The obtained results showed that the newly proposed methodology for validation of model of railway vehicles represents a more severe estimation of agreement between the simulation and experimental results than the metrics proposed in the project "DYNOTrain". Model validation performed using the newly proposed methodology provides an opportunity for reduction of the volume of expensive experimental tests

Cavitation resistance of the material PA 3200 GF produced by selective laser sintering

The present study focuses on the results of cavitation resistance research of samples obtained by the Selective Laser Sintering technology. The samples were made from polyamide powder reinforced with glass beads – PA 3200 GF. The laser-sintered samples were produced from 100% new and recycled powder mixed with 70% of new powder. The samples were tested under cavitation conditions using an ultrasonic vibration method with a stationary sample according to the ASTM G32 standard. Examination of the morphology of cavitation damage was investigated by scanning electron microscopy. The change in mass loss during different cavitation times was measured on the tested samples. The main objective of the research was to determine the validity of the application of the tested material in cavitation conditions