## 3 Results and Discussion
mentioned above, the loss factor values of PZT + SMA dispersed specimens were measured to be larger than the loss factor of neat specimens in the whole frequency range. It is interesting to note that the loss factor values of PZT + SMA dispersed specimens are higher than the specimens with SMA particles only in the whole frequency range. This is in contrast to the behavior of specimens with PZT particles; at 100-120 Hz, the PZT + SMA specimen had a lower loss factor value than the PZT particles specimen. [PERSON] et al. [26] showed that it is necessary for SMA to reach a temperature condition that can cause phase change inside the material in order to exhibit pseudoelasticity. It was also shown that the higher the temperature, the greater the energy consumed by deformation. Therefore, in SMA, the higher the temperature is, the faster the vibration energy can be dissipated. The thermal energy generated from the deformation of the PZT accelerates the phase change of the SMA when the piezoelectric material and the shape memory alloy are used simultaneously. Another point that can be seen from the above experimental results is that the loss factor value is negative at a specific frequency. This is due to the resonance phenomenon of the specimen, as the frequency range with negative loss factor is almost similar for all specimens. According to [PERSON] et al., as the specimen is scanned across its frequency range, the specimen-instrument system, such as a guitar string, begins to resonate when it reaches a certain frequency. These frequencies are either the natural resonant frequencies or harmonics of the sample-instrument system. In this set of experimental conditions, the sample-instrument system vibrates as a guitar string does, obscuring the desired information about the sample. Since this resonant behavior is a physical property of the system and there is no way to change it, the experiment must be redesigned by changing the sample dimensions or shape to avoid problems [27]. As mentioned above \"Preparation of Specimens\" section, all specimens used in this experiment have the same dimensions. Additionally, since the weight and elastic modulus are similar, it seems that resonance occurred at a similar frequency. The reason the negative value was measured can be seen as a calibration error of the measuring equipment or a calculation problem. However, before measuring the loss factor, the evaluation equipment should always be calibrated using a standard specimen before proceeding with the measurement. It seems that the direction of deflection of the specimen at the time of data measurement was measured as a negative number due to the resonance rather than the calibration of the measuring instrument, and the calculated value is considered to be negative. Normal values were output in the section  
Figure 9: Loss factors (tan \(\delta\)) of CFRP specimens with PZT, SMA and PZT/SMA mixed particle-dispersed mixture film. Measurement data for varying frequencies and different particle loadings. over 100 Hz outside the resonance frequency, and since the section intensively analyzed for material properties in this study is the section over 100 Hz, it is not expected to have a significant impact on the validity of the experimental results. Figure 10 shows the flexural modulus of the CFRP samples interleaved with PZT-, SMA-, and mixed-particle-dispersed mixture films. The measured values showed no significant change as the content of the particles increases regardless of the type of material. This indicates that the interleaved mixture film does not act as a defect that degrades the mechanical properties of the material. It is safe to say, therefore, that interleaving PZT, SMA, and PZT + SMA particles mixture films in composite laminates can improve vibration damping capability without deteriorating the mechanical properties of the material.