I have surveyed some materials such metal matrix composites(MMCs), ceramic and foamed metal with good damping capacity to absorb noise and wave propagation. i.e. with high shock absorption property. However, I would like to realize whether the microstructure of metal (such as grain shape, grain size, grain boundary, dislocation, and subgrain .etc.) is relative to damping capacity. Consequently, can anyone give me relevant information/advice? Thanks you in advance.
The specific damping capacity of a material, without taking into account the mechanical structure, is related to the presence of structure defects such as dislocations, point defects or grain boundaries. Such defects when excited at a certain frequency move back and forth with applied stress and dissipate energy producing what is called internal friction . The damping capacity or internal friction are measured with a vibrating sample. Inverted pendula are used for low frequencies such as 1 Hz or below ; vibrating reeds are used for KHz frequencies. Ultrasound transducers are used to produce MHz frequencies and in this case pulse echo methods are used. Generally damping mechanisms are thermally activated and depend on temperature and frequency since the defect relaxation time depends on a Boltzmann exponential factor. There are some mechanisms of "dry friction " type that are not thermally activated and therefore damp vibration on a larger frequency spectrum. The dependence of damping capacity or interna friction on frequency or temperature are given by internal friction spectra. The technique is called then mechanical spectroscopy.
These may be helpful:
1) "Effect of Microstructure on damping in Metal-Matrix Composites: A Review", by Suraj P Rawal et al., pages 158-173, 1992, ASTM STP 1169, M3D: "Mechanics and Mechanisms of Material Damping", edited by Vikram K. Kinra, Alan Wolfenden.
2) "Documentation of damping capacity of metallic, ceramic and metal-matrix composite materials", J. ZHANG, R. J. PEREZ, E. J. LAVERNIA, JOURNAL OF MATERIALS SCIENCE 28 (1993) 2395-2404.
3) "Damping behavior of discontinuously reinforced ai alloy metal-matrix composites",E. J. Lavernia, R. J. Perez, J. Zhang, Metallurgical and Materials Transactions A , November 1995, Volume 26, Issue 11, pp 2803-2818.
4) "A study on damping behaviour of aluminite particulate reinforced ZA-27 alloy metal matrix composites", Shanta Sastry, M. Krishna, Jayagopal Uchil,Journal of Alloys and Compounds 314 (2001) 268–274.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science