###### Abstract  
This study analyzes the modeling and dynamics of a novel passive multi-degree-of-freedom (MDOF) vibration isolation platform which can achieve a significant isolation effect. Symmetrical scissor-like structures (SLSs) are utilized in the proposed MDOF isolation platform as the supporting and isolation elastic components. Based on the mathematical modeling and theoretical analysis of the MDOF vibration isolation system with SLSs, the effects of structural parameters and joint friction on the stiffness and damping properties are investigated. It is shown that due to geometric relations within the SLSs, the natural frequencies can be reduced via adjusting structural parameters of the SLS for different direction vibration isolation. Theoretical and experimental results show that the SLS isolation platform can achieve much better loading capacity and vibration isolation performance simultaneously by only using linear passive components because of the MDOF adjustable stiffness property. Therefore, with low cost and energy consumption, the proposed novel isolation platform can improve the vibration suppression in various engineering practices.  
MDOF isolation platform; geometrical nonlinearity; vibration suppression; adjustable stiffness property +
Footnote †: journal: Applied Physics Letters  
_Applied Physics Letters_  
In the literature, the techniques of vibration isolation for multi-direction excitation with excellent isolation performance over a larger frequency region have always been an attractive and difficult research topic. For the MDOF vibration isolation platform, active controllers are the chief method [13; 14; 15; 25; 26; 27; 28; 29; 30; 31]. The key point of the mechanism of active control in a MDOF isolator is to generate anti-vibration forces in different directions by actuators and sensors in the designed system. The studies of MDOF isolation systems are focused on the controllers and control strategies. Different designs and the analysis of the dynamics of parallel mechanisms are studied [25; 26; 27; 28; 29; 30; 31], for example, a hybrid magnet consisting of an electromagnet and permanent magnets is used as the active actuators in [25; 26]. Although active controllers can actively isolate vibration and control vibration in a timely manner, considering the energy required by active actuators, passive isolation techniques provide higher stability without any external power [32].  
This paper proposed a MDOF isolation platform using SLSs as the elastic components. Then the natural frequencies and vibration responses are studied to show the isolation effectiveness of the proposed system. The multiple-degrees of freedom vibration isolation system can be achieved using only pure linear and passive elements in the system with a simple and flexible installation structure because of the adjustable stiffness. This system could provide an effective solution to many engineering problems for excellent MDOF vibration suppression and sustainable development for microgravity environments due to the multi-direction zero-stiffness property. The paper is organized as follows: The prototype of the isolation platform with SLSs is carried out and its mathematical modeling is obtained in Section 2. In Section 3, the responses of the isolation system obtained by the harmonic balance method (HBM) [33] and experiments are conducted, and the isolation effectiveness of the proposed isolation system is compared to the one using linear springs as isolators. A conclusion is drawn at the last section.