Written in English
|Statement||by Wayne Bennett.|
|The Physical Object|
|Pagination||58 leaves, bound :|
|Number of Pages||58|
Several types of damping are inherently present in a mechanical system. They are: 1. Internal (material) damping 2. Structural damping Fluid damping Internal (material) damping results from mechanical-energy dissipation within the material due to various microscopic and macroscopic by: Constrained layer damping (CLD) is an effective method for suppressing the vibration and sound radiation of lightweight structures. In this article, a two-level optimization approach is presented as a systematic methodology to design position layouts and thickness configurations of CLD materials for suppressing the sound power of vibrating. To determine the damping properties of materials in tension-compression, three-layer test specimens with a steel core and external layers of a soft damping material is used, whereas for the case. In general, materials selection and component design are two parallel streams followed when a mechanical component is designed. Firstly, a tentative material is chosen and data for it are assembled either from data sheets or from data books. In design, a choice of material can determine the price of a product and production paths.
The impulse excitation technique (IET) is a non-destructive material characterization technique to determine the elastic properties and internal friction of a material of interest. It measures the resonant frequencies in order to calculate the Young's modulus, shear modulus, Poisson's ratio and internal friction of predefined shapes like rectangular bars, cylindrical rods and disc shaped samples. An experimental technique for determining the internal loss factors (damping) of structures was investigated. The power input method (PIM) coupled with the use of a laser vibrometer allows for quick, and accurate measurements of loss factors of flat panel type structures. The effectiveness of. Internal damping 1 Structural damping 4 Fluid damping 5. CHAPTER 2 – MEASUREMENT OF DAMPING 6 CHAPTER 3 – MEASUREMENT OF DAMPING IN MECHANICAL SYSTEMS 10 Theoretical Analysis 10 First Method: Loss factor (η) vs. Moments & Forces 12 Second Method: Damping energy Hence, it is necessary to develop a new method for determining the internal damping coefficient and connecting the dynamic stiffness of fiber ropes based on the theory of structural dynamics. 3. Method for calibrating the internal damping coefficient Theory of structural dynamics for determining the internal damping coefficient.
This article describes a technique for measuring material damping in specimens under forced flexural vibration. Although the method was developed for testing fiber-reinforced composite materials, it could be used for any structural material. The test specimen is a double-cantilever beam clamped at its midpoint and excited in resonant flexural vibration by an electromagnetic shaker. Dynamic-mechanical properties (elastic modulus and internal damping) of materials may be characterized using either vibration or wave-propagation experiments. This section deals only with vibration-test methods, which cover the nominal frequency range – Hz. 2. Material damping Material damping depends on many factors. The most important of these factors are: type of materials, stress amplitude, internal forces, the number of cycles, sizes of geometry, the quality of surfaces and temperature. The factors were examined in Lazan book . Damping depends mainly on the stress amplitude as n. Concrete Damping Under steady state conditions, internal damping in prestressed concrete members may be less than 1% of critical if the initial prestress is sufficient to prevent tension cracks from developing. If tension cracks are allowed to develop, but on a miscroscopic scale, damping can be expected of the order of 2% of critical.