scholarly journals A Method of Reducing Motor Vibration: Natural Frequency, Damping Ratio, and Vibration Analysis of CFRP Motor Frame

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Jinguang Zhang ◽  
Hairu Yang ◽  
Xiong Li ◽  
Wei Ye
Keyword(s):  
Strain Energy ◽  
Damping Ratio ◽  
Vibration Reduction ◽  
The Finite Element Method ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Metal Frame ◽  
Metal Materials ◽  
Design And Manufacture ◽  
Motor Vibration

The existing motor frame is made of metal materials. In this paper, a carbon fiber reinforced plastic (CFRP) motor frame, which uses material damping to reduce vibration amplitude, which is proposed to design and manufacture low-vibration motors. The damp ratio of the CFRP motor frame is calculated by the damp prediction model based on strain energy, which is verified by the combination of the finite element method and experiment. The vibration characteristics of the CFRP frame motor are studied experimentally and compared with that of the metal frame motor. The results show that the CFRP frame motor has good vibration reduction. The amplitude reduction is up to 5 times higher than that of the metal motor frame, which proves that the damping vibration reduction of the CFRP motor frame has a good application value.

Enhancement of vibration characteristics in filament wound FRP composite shafts using nitinol wires

2018 ◽  
Vol 47 (5) ◽  
pp. 377-385 ◽  
Author(s):  
Kannan Murugesan ◽  
Kalaichelvan K. ◽  
M.P. Jenarthanan ◽  
Sornakumar T.
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Filament Winding ◽  
Fiber Reinforced ◽  
Content Type ◽  
Fiber Reinforced Plastic ◽  
Damping Characteristics ◽  
Filament Wound ◽  
Reinforced Plastic ◽  
Hollow Shafts

Purpose The purpose of this paper is to investigate the use of embedded Shape Memory Alloy (SMA) nitinol wire for the enhancement of vibration and damping characteristics of filament-wound fiber-reinforced plastic composite hollow shafts. Design/methodology/approach The plain Glass Fiber-Reinforced Plastic (GFRP) and plain Carbon Fiber-Reinforced Plastic (CFRP) hollow shafts were manufactured by filament winding technique. Experimental modal analysis was conducted for plain hollow shafts of C1045 steel, GFRP and CFRP by subjecting them to flexural vibrations as per ASTM standard C747, with both ends clamped (C-C) end condition to investigate their vibration and damping behavior in terms of first natural frequency, damping time and damping ratio. Nitinol wires pre-stressed at various pre-strains (2, 4 and 6 per cent) were embedded with CFRP hollow shafts following same manufacturing technique, and similar experimental modal analysis was carried out by activating nitinol wires. The first natural frequencies of all the shaft materials were also predicted theoretically and compared with experimental measurements. Findings Among the three materials C1045 steel, plain GFRP and plain CFRP, the vibration and damping behavior were found to be the best for plain CFRP. Hence, CFRP shafts were considered for further improvement by embedding nitinol wires at pre-stressed condition. For CFRP shafts embedded with nitinol wires, the damping time decreased; and damping ratio and first natural frequency increased with increase in percentage of pre-strain. In comparison with plain CFRP, 7 per cent increase in first natural frequency and 100 per cent increase in damping ratio were observed for nitinol embedded CFRP shafts with 6 per cent pre-strain. Theoretical predictions of the first natural frequencies agree well with the experimental results for all the shaft materials. Originality/value The effect of nitinol on vibration and damping characteristics of filament wound hollow CFRP composite shafts with different pre-strains has not been studied extensively by the previous researchers. This paper addresses the effect of embedded nitinol wires pre-stressed at three varied pre-strains, that is, 2, 4 and 6 per cent on the vibration and damping characteristics of composite hollow CFRP shafts manufactured by filament winding technique.

Vibration reduction of a flexible robot link using a frictional damper

2020 ◽  
pp. 107754632093609
Author(s):  
Hamed Biglari ◽  
Masoud Golmohammadi ◽  
Sajad Hayati ◽  
Siroos Hemmati
Keyword(s):  
Damping Ratio ◽  
Vibration Reduction ◽  
Flexible Manipulator ◽  
Test Results ◽  
The Finite Element Method ◽  
Flexible Robot ◽  
Nsga Ii ◽  
Modal Test ◽  
Realistic Situation ◽  
Euler Bernoulli Beam

One of the most important factors reducing flexible manipulator efficiency is the residual vibration occurrence. In this research, vibration reduction of flexible manipulators is investigated using an internal frictional damper. At first, the vibration equation of a manipulator is obtained using the finite element method with the Euler–Bernoulli beam element to study its vibrations in a reciprocal motion. In addition, an analytical model is developed to investigate the effect of the frictional damper on robot link vibrations. Using particle swam optimization, ICA, NSGA-II, and GWO methods, the optimal structure for the damper is obtained to maximize its effect. The optimally damped link is fabricated, and its dynamic characteristics are extracted from a modal test experiment. The modal test results show a considerable improvement in the damping ratio of the damped link in comparison with a simple link. The fabricated link samples are then tested in a realistic situation. The experimental results are in coincidence with the simulation results, certifying the performance of the proposed plan in vibration reduction of a robot link.

scholarly journals Self-Healing Structural Materials

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2297
Author(s):  
Seongpil An ◽  
Sam S. Yoon ◽  
Min Wook Lee
Keyword(s):  
Mechanical Properties ◽  
Extreme Environments ◽  
Structural Materials ◽  
Research Interest ◽  
Self Healing ◽  
Fiber Reinforced Plastic ◽  
Hard Materials ◽  
Plastic Composites ◽  
Reinforced Plastic ◽  
Metal Materials

Self-healing materials have been developed since the 1990s and are currently used in various applications. Their performance in extreme environments and their mechanical properties have become a topic of research interest. Herein, we discuss cutting-edge self-healing technologies for hard materials and their expected healing processes. The progress that has been made, including advances in and applications of novel self-healing fiber-reinforced plastic composites, concrete, and metal materials is summarized. This perspective focuses on research at the frontier of self-healing structural materials.

scholarly journals Effects of Long-Term Stowage on the Deployment of Bistable Tape Springs

2015 ◽  
Vol 83 (1) ◽  
Author(s):  
Alex Brinkmeyer ◽  
Sergio Pellegrino ◽  
Paul M. Weaver
Keyword(s):  
Strain Energy ◽  
Space Vehicle ◽  
Space Structures ◽  
Fiber Reinforced Plastic ◽  
Relaxation Effects ◽  
Long Duration ◽  
Reinforced Plastic ◽  
Modeling And Experiments ◽  
Deployment Time

In the context of strain-energy-deployed space structures, material relaxation effects play a significant role in structures that are stowed for long durations, for example, in a space vehicle prior to launch. Here, the deployment of an ultrathin carbon fiber reinforced plastic (CFRP) tape spring is studied, with the aim of understanding how long-duration stowage affects its deployment behavior. Analytical modeling and experiments show that the deployment time increases predictably with stowage time and temperature, and analytical predictions are found to compare well with experiments. For cases where stress relaxation is excessive, the structure is shown to lose its ability to deploy autonomously.

scholarly journals Sensitivity of the Viscous Damping Coefficient of Carbon Fiber in Carbon-Fiber-Reinforced Plastic with Respect to the Fiber Angle

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 781
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Damping Ratio ◽  
Damping Coefficient ◽  
Viscous Damping ◽  
Fiber Reinforced Plastic ◽  
Fiber Angle ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Reinforced Plastic ◽  
Derivatives Of

The variation in the viscous damping coefficient with the carbon fiber angle can be evaluated using the partial derivatives of the viscous damping coefficient with respect to the resonance frequency and modal damping ratio. However, the direct derivatives of the viscous damping coefficient were not effective solutions to the sensitivity analysis of carbon-fiber-reinforced plastic (CFRP) structures because the viscous damping from the binding matrix was not changed over the carbon fiber angle. If the identified viscous damping coefficients were assumed to be equivalent values from the parallel relationship between the binding matrix and carbon fiber, the relative error of the viscous damping coefficient of carbon fiber between the increased carbon fiber angle and reference angle could be used as the sensitivity index for the viscous damping coefficient of carbon fiber only. The modal parameters, resonance frequency, and modal damping ratio were identified from the experimental modal test of rectangular CFRP specimens for five different carbon fiber angles between 0° and 90°. The sensitivity of the viscous damping coefficient of carbon fiber was determined for two sensitivity indices: the direct derivative of the mass-normalized equivalent viscous damping coefficient and the relative error of the viscous damping coefficient of carbon fiber. The sensitivity results were discussed using the five mode shapes of the CFRP specimen, that is, three bending modes and two twisting modes.

scholarly journals Comparative Study of Damping in Pristine, Steel, and Shape Memory Alloy Hybrid Glass Fiber Reinforced Plastic Composite Beams of Equivalent Stiffness

2017 ◽  
Vol 68 (1) ◽  
pp. 91 ◽  
Author(s):  
Amit Kumar Gupta ◽  
R. Velmurugan ◽  
Makarand Joshi
Keyword(s):  
Shape Memory Alloy ◽  
Comparative Study ◽  
Shape Memory ◽  
Damping Ratio ◽  
Composite Beams ◽  
Gfrp Composites ◽  
Glass Fiber Reinforced Plastic ◽  
Fiber Reinforced Plastic ◽  
Glass Fiber Reinforced ◽  
Reinforced Plastic

<p class="p1">Several efforts were made over the years to control vibration of structural components made of composite materials. This paper consists of study on effect of using shape memory alloy (SMA) to increase the damping of glass fiber reinforced plastic (GFRP) composites. A comparative study between SMA and steel was made as reinforcement material in GFRP composites to enhance damping. Dimensions of each beam were calculated such that all the beams i.e. pristine GFRP beam, GFRP beam embedded with steel wires and GFRP beam embedded with SMA wires have same flexural stiffness and first mode of frequency of vibration. Damping ratio was measured experimentally through logarithmic decay method. Through experiments damping ratio obtained for SMA hybrid composite beam was found to be higher as compared to the pristine and steel hybrid GFRP composite beams.</p><p class="Text"><span> </span></p>

Stress Analysis of a Tire Under Vertical Load by a Finite Element Method

1977 ◽  
Vol 5 (2) ◽  
pp. 102-118 ◽  
Author(s):  
H. Kaga ◽  
K. Okamoto ◽  
Y. Tozawa
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Computer Program ◽  
Temperature Rise ◽  
Strain Energy ◽  
Internal Stresses ◽  
Vertical Load ◽  
The Finite Element Method ◽  
Internal Temperature ◽  
Element Method

Abstract An analysis by the finite element method and a related computer program is presented for an axisymmetric solid under asymmetric loads. Calculations are carried out on displacements and internal stresses and strains of a radial tire loaded on a road wheel of 600-mm diameter, a road wheel of 1707-mm diameter, and a flat plate. Agreement between calculated and experimental displacements and cord forces is quite satisfactory. The principal shear strain concentrates at the belt edge, and the strain energy increases with decreasing drum diameter. Tire temperature measurements show that the strain energy in the tire is closely related to the internal temperature rise.

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