2 edition of Measurement of damping of graphite epoxy materials & structural joints found in the catalog.
Measurement of damping of graphite epoxy materials & structural joints
by Mechanical Engineering Dept., Auburn University, National Aeronautics and Space Administration, National Technical Information Service, distributor in [Auburn, Ala.], [Washington, D.C, Springfield, Va
Written in English
|Statement||submitted by Malcolm J. Crocker ... [et al.].|
|Series||NASA contractor report -- NASA CR-183802.|
|Contributions||Crocker, Malcolm J., United States. National Aeronautics and Space Administration.|
|The Physical Object|
Manufacturing of a Scara Type Direct-Drive Robot with Graphite Fiber Epoxy Composite Material - Volume 9 Issue 2 - Dai Gil Lee, Ki Soo Kim, Yoon Keun Kwak Je Hoon Kim, Young Goo and Lee, Dai Gil Optimum bolted joints for hybrid composite materials. Composite Structures, Vol. 38 “Experimental Measurements of Material Damping in. Free and forced vibration methods were employed to measure the damping ratios of several graphite-epoxy samples. The damping ratio was computed by an improved half-power points method. The effect of outgassing (moisture desorption) on the damping was determined by measuring the damping ratio of a tube specimen in a vacuum environment before and after outgassing had occurred.
Damping is quantitatively represented by a damping measure, typically the damping ratio [45, 59], to indicate the magnitude of the damping of a structure in actual applications. The damping ratio can be estimated through the procedure of parameter identification from vibrational responses of a structure. TGA was used to assess the thermal degradation temperatures of pure PU foams, PU-based graphite foams (PG), PGS with a volume ratio of AgNWs to graphite (), and PGSE composite with a volume ratio of AgNWs to graphite (). Before the addition of epoxy resin (EP), all materials showed a two-stage degradation: an early stage starting at.
The requirement for practical engineering materials is that the tan δ value should be above and temperature range of tan δ > should be as wide as possible. 8–10 However, good damping performance of polymers is usually limited to a narrow temperature range of T g ± 10 °C, which limits their practical use. 11 Many techniques have. alloy and graphite/epoxy composites in bending, damping is independent ofstrain and frequency as long as strain is below 10 microstrains. Above microstrain, material damping increases with increasing strain . Experinlents with graphite/epoxy composites, also inbending, have shown that .
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Internal damping in the structural material, by friction in the connecting joints, or by active control (refs.
3 and 4). The intent of this investigation was to measure the internal damping and dynamic stiffness of the graphite/epoxy composite material used in the columns, and. Get this from a library. Measurement of damping of graphite epoxy materials & structural joints: period, October - June final report.
[Malcom J Crocker; United States. National Aeronautics and Space Administration.;]. Measurement of damping of graphite epoxy materials (OCoLC) Microfiche version: Crocker, Malcolm J. Measurement of damping of graphite epoxy materials (OCoLC) Material Type: Document, Government publication, National government publication, Internet resource: Document Type: Internet Resource, Computer File: All Authors.
measurement of damping of graphite epoxy materials & structural joints--l o _'_._ z'o z _3 i m l-3 r-_=_ r_ f_ sponsored by: national aeronautics & space administration george c. marshall space flight center huntsville,al research rep rt submitted by: malcolm j. crocker mohan d. rao p.k. raju xinche yan mechanical engineering department.
The damping capacity of graphite epoxy materials and structural joints was evaluated. The damping ratio of different composite specimens and bonded joints were systematically evaluated under normal atmospheric conditions and in a vacuum environment.
Free and forced vibration test methods were employed for measuring the damping ratios. The advantages and limitations associated with each model/method will be described in the context of recent experimental study of the damping of graphite epoxy composite materials and joints.
Then, current research on the prediction of modal parameters (resonance frequencies, loss factors, and mode shapes) of bonded composite structural joints. FIGURE 3 Variation of the damping loss factor for graphite/epoxy (CFRP) and glass/epoxy (GFRP) unidirectional composite materials as a function of fiber volume fraction tested in flexure (after Adams.
material damping energy balance approach fluid damping structural damping damping mechanism in composite materials visco elastic damping 15 factors affecting visco elastic damping materials utilised mathematical modelling 17 structural damping factor.
3. Damping test methods The loading–unloading tests. There are a variety of experimental methods available to measure the damping properties of materials, including logarithmic decrement δ, specific damping capacity (SDC), inverse quality factor Q −1, damping ratio ξ and loss factor η.
The inverse quality factor, Q −1, is widely used to characterize material damping through Q. DAMPING PROPERTIES OF MATERIALS Revision C By Tom Irvine Email: [email protected] November 8, _____ The purpose of this tutorial is to give typical damping values for various materials and systems.
The data in Tables 1 and 2 is taken from Reference 1. Table 1. Static Properties of Materials under Standard Conditions (approx. 20° C. Composites Science and Technology 40 () Characterization of the Vibration Damping Loss Factor of Glass and Graphite Fiber Composites Roger M.
Crane David Taylor Research Center, CodeAnnapolis, MarylandUSA & John W. Gillespie, Jr Center for Composite Materials, Department of Mechanical Engineering and Materials Science Program, University of.
Damping characteristics in terms of the loss factor are presented for this epoxy and some structural metals. Though the damping of the epoxy was larger than that of any metal tested, it can still be considered small.
Portal frames were modeled using the epoxy. Natural frequencies of vibration for the metal frames and epoxy models were determined. graphite/epoxy composites. These materials have been used to meet a wide variety of design param eters ranging from minimal weight to high struc tural stiffness requirements.
Because of their ability to meet many diverse design requirements simulta neously the use of graphite/epoxy composites is expected to increase. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping.
The advantages and limitations associated with each model/method will be described in the context of recent experimental study of the damping of graphite epoxy composite materials and joints. The material damping of a quasi-isotropic graphite/epoxy panel, with a (0, ±, )s layup in the skin, has a viscous damping ratio around i5.
combined finite element and frequency response was developed to measure the damping properties of composite material. EXPERIMENTATION In this work carbon fiber/epoxy (CFRP) and glass fiber/epoxy (GFRP) were tested for their damping properties.
The specimens of dimensions x 30 x 2 mm were fabricated by the standard process . The. AbstractThe present study investigates the influence of graphene nanopellets (GnPs) on the damping and vibration characteristics of fiber-reinforced basalt/epoxy composites for different weight contents of GnPs particles (, and wt%).
The variation of dynamic properties in terms of loss and storage modulus was explored by using the experimental modal analysis. Crocker, M. J., Raju, P. K., Rao, M. and Yan, Xinche,“Measurement of Damping of Graphite Epoxy Materials & Structural Joints,”NASA New Technology Report MFS Suarez, S.
A., Gibson, R. and Deobold, L. R.,“Random and Impulse Techniques for Measurements of Damping in Composite Materials,” Experimental Techniques, Vol. 8, No. 10, pp. 19– RESONANCE September GENERAL ARTICLE ways: by adding a mass (mass damper), by hysteresis propertiesdue to the molecular structure (material damping), by friction/rubbing/impact at the structural joints and supports (structuraldamping).Vibrations can be cancelled as in the case of.
In this thesis, the composite materials considered are E – Glass Epoxy and S2 Glass Epoxy. The material for damping is rubber.
The structural analysis will be done to verify the strength of the shaft and compare the results for three materials. Modal analysis will also be done on the shaft to determine mode shapes. Analysis will be done in.Dynamic elastic moduli and damping of carbon- and graphite-filled epoxy composites have been measured over the temperature range of 85 to ° K.
The epoxy resin matrix was cured with diethylenetriamine.In recent years, it has been found that composites co-cured with viscoelastic materials can enhance the damping capacity of a composite structural system with little reduction in stiffness and.