Simplified performance indices and active control force of vibration isolation systems with elastic base

Influence of the elasticity of the base on vibration isolation performances of single layer, double layer and floating raft vibration isolation systems is investigated systematically. Characteristics of vibration coupling between different vibration isolation systems and different elastic bases are analyzed. Moreover the characteristics of vibration acceleration level difference and force transmissibility of different vibration isolation systems are discussed and their simpli- fled expressions are given. In addition the required control forces of active vibration isolation under different installations of actuators for different vibration isolation systems are compared. The results show that for all vibration isolation systems, the addition of the stiffness and damping of the base can enhance their vibration acceleration level difference and force transmissibility. Moreover for floating raft vibration isolation system, the addition of the stiffness and damping of the raft can enhance its vibration isolation performance and reduce the control force required bv active vibration isolation.

Elastic-plastic deformation of sandwich rod on elastic basis

Sandwich composite material possesses advantages of both light weight and high strength. Although the mechanical behaviors of sandwich composite material with the influence of single external environment have been intensively studied, little work has been done in the study of mechanical property, in view of the nonlinear behavior of sandwich composites in the complicated external environments. In this paper, the problem about the bending of the three-layer elastic-plastic rod located on the elastic base, with a compressibly physical nonlinear core, has been studied. The mechanical response of the designed three-layer elements consisting of two bearing layers and a core has been examined. The complicated problem about curving of the three-layer rod located on the elastic base has been solved. The convergence of the proposed method of elastic solutions is examined to convince that the solution is acceptable. The calculated results indicate that the plasticity and physical nonlinearity of materials have a great influence on the deformation of the sandwich rod on the elastic basis.

Microscopic elasticity imaging of vessel walls based on intravascular ultrasound

The effect of the transducer eccentricity on grayscales of intravascualr ultrasound images was corrected based on the scattering properties of high frequency ultrasound in vessel walls. The displacement and strain distributions of vessel walls produced by tissue microelement motion were obtained using a novel motion estimation method in steps and sum based on the optical flow and genetic algorithm. Furthermore, authors firstly reconstructed 'real' elasticity distribution images of cross section tissues of vessel walls in the world. In vitro experimental results of porcine artery demonstrated the methods mentioned above are reasonable. Experimental investigation of vascular mechanics can be advanced to 2D sub-millimeter microstructure levels. These studies have potential to provide new technology means in monitoring and evaluation of Percutaneous transluminal coronary angioplasty process.