Validação do conjunto Powertrain de um veículo tipo Baja SAE utilizando a metodologia de projeto de experimentos (DOE)
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Data
2024-12-05
Autores
Orientador
Garcia, Rafael Farias
Banca
Lagemann, Carlos Henrique
Lago, Guilherme Leite
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Resumo
O projeto Baja SAE é uma competição de Engenharia entre universidades, que consiste na fabricação de um veículo off road. No powertrain de um Baja SAE, as transmissões utilizadas geralmente são do tipo CVT (transmissão de variação contínua) por polias expansivas, sendo um dos componentes mais influentes no desempenho, visto que os motores são limitados por regulamento. O setup da CVT é crucial para um bom rendimento, na transmissão, juntamente com o atrito, o deslizamento da correia pode gerar calor e aumentar a temperatura do conjunto, consequentemente reduzindo sua eficiência. Sabendo que para tirar o veículo do repouso, a CVT desliza a correia sobre a polia, a aceleração do motor está diretamente relacionada ao aumento do esforço e ganho de temperatura no conjunto. Visto a importância destas relações, este trabalho utilizou a metodologia Box-Behnken Design (BBD), uma ferramenta estatística facilitadora que reduz o número de testes para encontrar a combinação perfeita das variáveis de entrada, além de simplificar o tratamento dos dados coletados. Para quantificar os resultados, foi utilizada a distância percorrida em teste de tração, similar ao que é realizado nas competições da SAE. Foram realizados 45 testes com 15 combinações aleatorizadas pelo BBD, com auxílio do software minitab® (versão de avaliação), foram encontradas as equações de regressão e representado o modelo estatístico deste experimento. Analisando os dados coletados, percebe-se que acelerações entre 75 e 100% e temperaturas entre 40ºC e 55ºC entregam desempenho satisfatório quando combinadas corretamente com outros parâmetros, enquanto os pesos, tendem a dar resultados positivos com 110g. Através de uma análise de variância (ANOVA), foi constatado que os 3 parâmetros de entrada são relevantes sobre o resultado, tendo destaque para o % de aceleração, que apresentou influência exponencial sobre a variável de saída, atingindo um nível de 69,32% de contribuição. Os pesos apresentaram 9,08% de contribuição, possuindo relação significativa com a aceleração, um depende do outro para potencializar o resultado. A temperatura, com 2,97% de contribuição, se mostrou um fator secundário, amenizando ou potencializando os efeitos das outras 2 variáveis. Por fim, a combinação ideal apontada pelo modelo estatístico ficou em 110g, 51ºC e 88% de aceleração.
The Baja SAE project is an Engineering competition between universities, which consists of manufacturing an off-road vehicle. In the powertrain of a Baja SAE, the transmissions used are generally of the CVT type (continuous variable transmission) using expanding pulleys, being one of the most influential components in performance, as the engines are limited by regulation. The CVT setup is crucial for good performance. In the transmission, together with friction, the slipping of the belt can generate heat and increase the temperature of the assembly, consequently reducing its efficiency. Knowing that to take the vehicle from rest, the CVT slides the belt over the pulley, engine acceleration is directly related to the increase in effort and temperature gain in the assembly. Given the importance of these relationships, this work used the Box-Behnken Design (BBD) methodology, a facilitating statistical tool that reduces the number of tests to find the perfect combination of input variables, in addition to simplifying the treatment of collected data. To quantify the results, the distance covered in the traction test was used, similar to what is carried out in SAE competitions. 45 tests were carried out with 15 combinations randomized by BBD, with the help of minitab® software (free tryal), the regression equations were found, and the statistical model of this experiment was represented. Analyzing the data collected, it is clear that accelerations between 75 and 100% and temperatures between 40ºC and 55ºC deliver satisfactory performance when correctly combined with other parameters, while weights tend to give positive results at 110g. Through an analysis of variance (ANOVA), it was found that the 3 input parameters are relevant to the result, with emphasis on the % of acceleration, which had an exponential influence on the output variable, reaching a level of 69.32% of contribution. The weights presented a 9.08% contribution, having a significant relationship with acceleration, one depends on the other to enhance the result. Temperature, with a 2.97% contribution, proved to be a secondary factor, mitigating or enhancing the effects of the other 2 variables. Finally, the ideal combination indicated by the statistical model was 110g, 51ºC and 88% acceleration.
The Baja SAE project is an Engineering competition between universities, which consists of manufacturing an off-road vehicle. In the powertrain of a Baja SAE, the transmissions used are generally of the CVT type (continuous variable transmission) using expanding pulleys, being one of the most influential components in performance, as the engines are limited by regulation. The CVT setup is crucial for good performance. In the transmission, together with friction, the slipping of the belt can generate heat and increase the temperature of the assembly, consequently reducing its efficiency. Knowing that to take the vehicle from rest, the CVT slides the belt over the pulley, engine acceleration is directly related to the increase in effort and temperature gain in the assembly. Given the importance of these relationships, this work used the Box-Behnken Design (BBD) methodology, a facilitating statistical tool that reduces the number of tests to find the perfect combination of input variables, in addition to simplifying the treatment of collected data. To quantify the results, the distance covered in the traction test was used, similar to what is carried out in SAE competitions. 45 tests were carried out with 15 combinations randomized by BBD, with the help of minitab® software (free tryal), the regression equations were found, and the statistical model of this experiment was represented. Analyzing the data collected, it is clear that accelerations between 75 and 100% and temperatures between 40ºC and 55ºC deliver satisfactory performance when correctly combined with other parameters, while weights tend to give positive results at 110g. Through an analysis of variance (ANOVA), it was found that the 3 input parameters are relevant to the result, with emphasis on the % of acceleration, which had an exponential influence on the output variable, reaching a level of 69.32% of contribution. The weights presented a 9.08% contribution, having a significant relationship with acceleration, one depends on the other to enhance the result. Temperature, with a 2.97% contribution, proved to be a secondary factor, mitigating or enhancing the effects of the other 2 variables. Finally, the ideal combination indicated by the statistical model was 110g, 51ºC and 88% acceleration.
Descrição
Palavras-chave
Baja SAE; Powertrain; Transmissão CVT; Box-Behnken Design (BBD); CVT transmission
Citação
BERGAMASCHI, Vinicius. Validação do conjunto Powertrain de um veículo tipo Baja SAE utilizando a metodologia de projeto de experimentos (DOE). 2024. Monografia (Graduação em Engenharia Mecânica) – Universidade do Vale do Taquari - Univates, Lajeado, 05 dez. 2024. Disponível em: http://hdl.handle.net/10737/4676.