Abstract:The objective of this study is to analyze the dynamic behavior of composite shafts with particular interest on estimation of damping. The composite shafts have been chosen as potential candidates for the replacement of conventional metallic shafts in many applications. This study analyzed the dynamic behavior of different materials such as glass/epoxy, carbon/epoxy, and boron/epoxy at different speeds. Detailed dynamic studies on the effect of different materials, stacking sequences on the unbalance responses,… Show more
“…Ramkumar et al 10 predicted the damping values of composite box beam in ANSYS by the use of 3D beam and thin plate finite elements to study the influence of length/height ratio, width/height ratio, and ply angle effect on vibration. Alwan et al 11 performed experimental modal analysis of composite tube shafts and solid shafts and demonstrated that the experimental results agree well with the ANSYS results. The detailed literature survey also reveals that there is relatively very less experimental work conducted on vibration characteristics of polymer composite beams at different end boundary conditions for various cross-sectional shapes.…”
Vibration characteristics of carbon/epoxy composite beams await increased attention in structural industries such as aerospace, automotive, machine tools, marine industries. The objective of the present work is to investigate and analyze the shape effects of carbon/epoxy composite beams on vibration behavior. Specimens were fabricated using woven carbon fabric for basic shapes: I, box, and channel sections by hand layup method. The fabricated beams were subjected to impulse frequency response test under cantilever and fixed-end boundary conditions for free vibration test up to 3.5 kHz. Vibration response was measured using piezoelectric transducer and was recorded using computer-controlled data acquisition system for analyzing its behavior. The vibration characteristic of beams with various shapes shows modified performance under different boundary conditions. The experimental mode shapes and modal frequencies of beams are discussed and compared for successive resonance sets. At a lower frequency range of 3.5 kHz, the experimental modal responses of beam that were compared with modal results of finite element method analysis using software ANSYS V12Õ exhibited acceptable deviation in error maximum of up to 8.2%. Further, all deformed mode shapes of various shaped beams tested at increased frequency level of 12 kHz using finite element software were also observed and discussed.
“…Ramkumar et al 10 predicted the damping values of composite box beam in ANSYS by the use of 3D beam and thin plate finite elements to study the influence of length/height ratio, width/height ratio, and ply angle effect on vibration. Alwan et al 11 performed experimental modal analysis of composite tube shafts and solid shafts and demonstrated that the experimental results agree well with the ANSYS results. The detailed literature survey also reveals that there is relatively very less experimental work conducted on vibration characteristics of polymer composite beams at different end boundary conditions for various cross-sectional shapes.…”
Vibration characteristics of carbon/epoxy composite beams await increased attention in structural industries such as aerospace, automotive, machine tools, marine industries. The objective of the present work is to investigate and analyze the shape effects of carbon/epoxy composite beams on vibration behavior. Specimens were fabricated using woven carbon fabric for basic shapes: I, box, and channel sections by hand layup method. The fabricated beams were subjected to impulse frequency response test under cantilever and fixed-end boundary conditions for free vibration test up to 3.5 kHz. Vibration response was measured using piezoelectric transducer and was recorded using computer-controlled data acquisition system for analyzing its behavior. The vibration characteristic of beams with various shapes shows modified performance under different boundary conditions. The experimental mode shapes and modal frequencies of beams are discussed and compared for successive resonance sets. At a lower frequency range of 3.5 kHz, the experimental modal responses of beam that were compared with modal results of finite element method analysis using software ANSYS V12Õ exhibited acceptable deviation in error maximum of up to 8.2%. Further, all deformed mode shapes of various shaped beams tested at increased frequency level of 12 kHz using finite element software were also observed and discussed.
“…An instrumented impact hammer was used to hit the specimen, and the response signal was sensed and measured by the accelerometer and the data acquisition card (DEWESoft, Dewteron Corp., Austria); the observed data were then transmitted to a PC where the natural frequencies were determined. Further, the loss factors, η were estimated by the half power bandwidth method, used elsewhere 17–25 ; the expression for the same is as follows Figure 4.Schematic representation of impulse testing.…”
This paper reports the effect of temperatures (30 C to 80 C, with incremental steps of 5 C) and orientations of the glass fibers (0 , 30 , 45 , 60 and 90 ) on the dynamic properties (the loss factors and the natural frequencies) of polypropylene honeycomb sandwich composites. The impulse technique has been employed to calculate the natural frequency and loss factor of the sandwich specimens under different temperatures. The natural frequency and loss factor values have also been calculated theoretically using Blevins's formulae for natural frequency, and Yim et al.'s transverse shear effect, respectively. The values of damping loss factor and the natural frequency/stiffness are the maximum at 0 fiber orientation in the skins of the sandwich specimen. The loss factor of the same oriented specimen increases sharply with the increase in temperature. The main reasons for the above are the higher in-plane strength of skins and lower transverse shear strength of the honeycomb core. Hence, the 0 fiber oriented sandwich specimen is more desirable than the other fiber oriented specimens at all temperatures. A good agreement is observed between the experimental and theoretical values.
“…The study incorporated the rotary inertia, gyroscopic effects, transverse shear deformation, and the coupling effect due to the lamination of composite layers. Alwan et al [15] analyzed solid shafts and composite tube shafts using ANSYS. Boukhalfa [16] considered the dynamic behavior of the spinning Functionally Graded Material (FGM) shaft on rigid bearings.…”
A refined variational asymptotic method (VAM) and Hamilton’s principle were used to establish the free vibration differential equations of a rotating composite thin-walled shaft with circumferential uniform stiffness (CUS) configuration. The generalized differential quadrature method (GDQM) was adopted to discretize and solve the governing equations. The accuracy and efficiency of the GDQM were validated in analyzing the frequency of a rotating composite shaft. Compared to the available results in literature, the computational results by the GDQM are accurate. In addition, effects of boundary conditions, rotating speed, ply angle, ratio of radius over thickness, and ratio of length over radius on the frequency characteristics were also investigated.
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