INVESTIGATION OF NATURAL FREQUENCY CHANGE DEPENDING ON THE DIFFERENT TEST TEMPERATURES IN PASSENGER CAR LIGHTING ELEMENTS

Abstract

In this study, natural frequency scanning of a passenger vehicle lighting housing made of 40% talc mixed polypropylene (PP TD40) was performed by using electrodynamic shaker. Tests were performed at different test temperatures of 23 °C, 70 °C and -10 °C. The time-dependent acceleration graphs of these tests have been converted to frequency-dependent acceleration graphs with the aid of the "Fast Fourier Transformation" method. The natural frequencies of the part and the damping rates at these frequencies were calculated from these graphs using the half power method. The calculated damping rates for each resonance frequency were then entered into the Ansys software and the results were compared. The correlation between the results of the analysis in comparison with the test results were 11.3% and a maximum of at least 0.26%.

Keywords

• Natural frequency
• Passenger vehicle lighting
• Modal analysis
• Damping ratio
• Fast fourier transform.

BİR BİNEK ARAÇ AYDINLATMA ELEMANINDA DOĞAL FREKANSLARIN FARKLI TEST SICAKLIĞINA BAĞLI DEĞİŞİMİNİN İNCELENMESİ

Abstract

Bu çalışmada, %40 talk katkılı polipropilenden (PP TD40) imal edilmiş bir binek araç aydınlatma elemanını gövdesinin elektrodinamik sarsıcı kullanılarak doğal frekans taraması yapılmıştır. Testler 23 °C, 70 °C ve -10 °C farklı test sıcaklıklarında gerçekleştirilmiştir. Bu testlerin çıktısı olan zamana bağlı ivme grafikleri “Hızlı Fourier Dönüşümü” yöntemi yardımı ile frekansa bağlı ivme grafiklerine dönüştürülmüştür. Yarım güç metodu kullanılarak bu grafiklerden gövdenin doğal frekansları ve bu frekanslardaki sönüm oranları hesaplanmıştır. Ardından hesaplanan sönüm oranları Ansys yazılımına girilerek sonuçlar karşılaştırılmıştır. Karşılaştırma sonucunda test ile analiz sonuçları arasında korelasyon en fazla %11,3 ve en az %0,26 olmuştur.

Keywords

• Doğal frekans
• Binek araç aydınlatma
• Modal analiz
• Sönüm oranı
• Hızlı fourier dönüşümü

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