Estimation of the 3D Printing Filling Density Effect on Natural Frequency and Damping Ratio and the Optimal Filling Density of Robot Structure

In this study, we measured the natural frequency and damping ratio of onyx-material robot arm specimens and obtained the variation law of the Young’s modulus and attenu- ation coefficient with filling density. Based on this, we obtained the equations for estimating the natural frequency and damp- ing ratio of robot arm specimens for any filling density and size. This equation allows estimating its vibration characteristics even without printing the robot arm. Finally, we combined the equations for calculating the natural frequency and damping ratio with those for the settling time and investigated how to determine the optimal filling density under different loads. The results show that the anti-vibration effect of the specimen is the worst for a filling density of 25-30%. Therefore, this filling density should be avoided. We also found that the settling time for a 10% filling density is shorter than that of many specimens with a high filling density. To achieve light weights, a 10% filling density may be an option. The proposed equations and curves can provide guidelines to design a robot arm with anti-vibration effect.