ANALISIS KESALAHAN MAGNITUD FRF SISTEM GETARAN DUA DERAJAT KEBEBASAN

• Main Author: Suryadi, Dedi
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/38246
• Institution: Institut Teknologi Bandung

Investigation related with the influence of time record to the value of FRF’s magnitude has been conducted by previous researchers. This phenomena commonly found in FRF measurement on light structure using impulse excitation method with small disintegration constant. Unfortunately, previous researchs had not yet mathematically reveal the relationship between time record and error on FRF’s magnitude obtained from measurement using impulse excitation method on two degrees of freedom system. In fact, this relationship is very important in order to find out parameters that significantly influence the FRF measurement using impulse excitation method. The parameter will give good approach of the actual condition encountered in field. In this research, analysis of impulse response spectrum error in two degrees of freedom using proportional damping and general damping is done. The output of this analysis are mathematical equations which accurately calculate the percentage of magnitude error of the impulse response spectrum. To validate the mathematical equations, numerical approach is also conducted. Validation is done by comparing the mathematical calculation result with the simulation result from MATLAB. The next step is to observe the influence of each parameter toward the impulse response spectrum error. Based on the equation derived, observation result of each parameter is presented. Therefore, optimum combination of parameters is obtained. The optimum combination is then used to minimize the FRF’s magnitude error. From the combination of parameters can be concluded that the number of frequency line and the value of the highest natural frequency divided by the frequency span, give the same influence to the FRF’s magnitude error. This is valid for either proportional or general damping case. In other words, treatment given to reduce the FRF’s magnitude error during measurement will be the same for both proportional and general damping case.