Penilaian Sifat Dinamik Lekapan Getah di bawah Syarat Beban Pra-Statik Pelbagai

Evaluation of the Dynamic Properties of Rubber Mounts under Varying Pre-Static Loading Conditions

Abstract

Kajian ini memfokuskan kepada penilaian sifat-sifat lekapan getah di bawah pengaruh beban pra-statik. Sifat dinamik bahan viskoelastik seperti getah adalah bersandarkan frekuensi dan dipengaruhi oleh perbezaan beban pra-statik yang dikenakan. Eksperimen ini direkabentuk dan dimodelkan sebagai sistem darjah kebebasan tunggal (SDOF) dalam kajian getaran. Variasi beban pra-statik dilaksanakan menggunakan beberapa blok silinder dengan diameter seragam tetapi mempunyai ketinggian dan jisim yang berbeza. Dapatan kajian menunjukkan bahawa hubungan antara sifat lekapan getah dan beban pra-statik berubah mengikut rantau frekuensi yang berbeza. Pada julat frekuensi di bawah frekuensi asli, nilai Fungsi Respons Frekuensi (FRF) meningkat seiring dengan peningkatan beban pra-statik, di mana jisim beban yang lebih besar memberikan kesan yang lebih signifikan. Bagi julat frekuensi asli, nilai FRF meningkat sehingga mencapai tahap maksimum yang menunjukkan frekuensi asli sistem tersebut. Sebaliknya, pada julat di atas frekuensi asli, peningkatan beban pra-statik menyebabkan penurunan nilai FRF. Dari aspek kekakuan bersandarkan frekuensi, didapati bahawa semakin besar jisim beban pra-statik, semakin rendah nilai kekakuan pada semua julat frekuensi, kecuali di sekitar frekuensi resonans. Selain itu, perbandingan pada titik resonans bagi setiap sistem menunjukkan bahawa faktor kehilangan lekapan getah berkurangan apabila beban pra-statik meningkat.

This study focuses on evaluating the characteristics of rubber mounts under the influence of pre-static loading. The dynamic properties of viscoelastic materials, such as rubber, are frequency-dependent and significantly affected by variations in the applied pre-static load. In this vibration study, the experiment is designed and modeled as a single-degree-of-freedom (SDOF) system. Variations in pre-static loading are implemented using several cylindrical blocks with uniform diameters but varying heights and masses. The findings indicate that the relationship between rubber mount properties and pre-static loading shifts across different frequency regions. In the frequency range below the natural frequency, the Frequency Response Function (FRF) values increase as the pre-static load increases, with larger masses producing more significant effects. Within the natural frequency range, the FRF value increases until it reaches a maximum peak, identifying the system's resonance. Conversely, in the range above the natural frequency, an increase in pre-static loading leads to a decrease in FRF values. Regarding frequency-dependent stiffness, it was observed that a higher pre-static mass results in lower stiffness values across all frequency ranges, except in the vicinity of the resonance frequency. Furthermore, a comparison at the resonance points for each system reveals that the loss factor of the rubber mount decreases as the pre-static load increases.