# Comparing Bol Implementation Methods in Vibration Testing for Accurate Dynamic Behavior Analysis
## 2 Materials and Methods
### Comparison of Analysis and Test Results  
This study was conducted to identify the optimal bolt connection method by comparing the natural frequencies and mode shapes observed in the jig for various bolt connection methods against vibration test results. The comparison was conducted by evaluating the representativeness of the bonded connection method in vibration testing. It involved analyzing changes in the jig's natural frequencies and mode shapes depending on the connection method, assessing the similarity with test results, and performing an efficiency analysis.  
First, the study evaluated whether the bonded connection method, which is the most common method used to represent bolt connections, effectively represents vibration testing. For this purpose, the jig's natural frequencies derived from vibration testing were compared with those obtained through bonded-based vibration analysis. Here, natural frequency refers to the frequency at which resonance occurs at the Top Head of the jig (493.2 Hz).  
Second, the study analyzed whether there were similarities or differences in the jig's natural frequencies and mode shapes depending on the bolt connection method. For this analysis, the first natural frequencies and mode shapes of the jig were compared for each bolt connection method [12; 30; 31]. The first natural frequency is the most sensitive indicator of structural stiffness and directly reflects changes in bonding strength and stiffness caused by different connection methods. Additionally, the first natural frequency represents the overall dynamic characteristics of the structure and serves as a critical criterion in design and analysis [32; 33; 34].  
Third, the bolt connection method that produces natural frequencies most similar to those of the vibration test was determined. For this, the natural frequencies of the Top Head measured during vibration testing were compared with those calculated for each bolt connection method. Through this comparison, the connection method showing natural frequencies closest to the test results was selected.  
Fourth, the efficiency of the analysis for each bolt connection method was compared. For this purpose, the CP Time and total memory usage required for the analysis of each connection method were analyzed. CP Time represents the total processing time the CPU spends on actual computation during the analysis and reflects the complexity of an analysis model and the efficiency of computational tasks. The total memory usage serves as a metric to assess the complexity and resource consumption of the analysis model. High memory requirements can slow down the analysis or even cause it to fail, making memory usage an important metric. Additionally, the time and effort required for generating finite element  
Figure 6: Vibration testing equipment and jig: (**a**) top view, (**b**) isometric view (analysis model), (**c**) isometric view (experimental model).  
models of bolts and the fastening procedures during preprocessing were also analyzed to comprehensively evaluate the usability of each connection method.