Characterization of Shape-Changing Panels With Embedded Rubber Muscle Actuators

2012 ◽  
Author(s):  
Larry D. Peel ◽  
Enrique Molina ◽  
Jeff Baur ◽  
Ryan Justice
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Water Pressure ◽  
Mechanical Energy ◽  
Fluid Pressure ◽  
Laminated Plate ◽  
Element Analysis ◽  
Plate Models ◽  
Optimal Spacing ◽  
Muscle Actuators

There is great interest in making shape-changing aircraft structures that are more biomimetic. Cylindrical McKibben-like flexible actuators efficiently convert fluid pressure into mechanical energy and thus offer excellent force-to-weight ratios while behaving similar to biological muscle. McKibben-like Rubber Muscle Actuators (RMAs) were embedded into elastomer panels. The effect of actuator spacing on the performance of these shape-changing panels was investigated. The work included nonlinear finite element analysis, fabrication, and testing of panels where four RMAs were spaced side-by-side, 1/2, 1, and 1.3 RMA diameters apart. Nonlinear “Laminated Plate” and “Rod & Plate” finite element models of individual RMAs were created from existing RMA dimensions. After adjusting for an initial “activation pressure,” the models produced realistic RMA forces. The laminated plate models used less computer resources, but only produced small amounts of actuator contraction (actuator strain). The more resource-intensive Rod & Plate models better replicated fiber/braid re-orientation and produced axial strains up to 60% of test values. Three types of embedded RMA panel FEA models; a “2D Cross-Section,” a “Full 3D Panel” (with either Laminated Plate or Rod & Plate RMAs) and a “3D Unit Cell” (also with either Laminated Plate or Rod & Plate RMAs). The Full 3D Rod & Plate model gave the most accurate strains and forces, but required unsustainable levels of computing resources. The 2D cross-section model predicted optimal RMA spacing to be at 1 diameter. All other FEA models show optimal panel performance between 1/2 and 1 diameter spacing. Panels with embedded RMAs were fabricated and tested with air or water pressure. Panel force as a function of pressure and as a function of contraction (strain) was obtained. Overall, FEA and test results for panels indicate that optimal performance occurs when the RMAs are spaced between 1/2 to 1 diameter apart. Actuator force as a function of spacing is fairly flat in this region, indicating that minor design or manufacturing differences may not significantly affect performance. However, the total amount of axial contraction decreases significantly at greater than optimal spacing. Useful design, simulation, and test methodologies for embedded RMA panels have been demonstrated.

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

Finite Element Analysis for the Collapse Accident of a 110kV Transmission Tower

2014 ◽  
Vol 986-987 ◽  
pp. 927-930
Author(s):  
Yi Zhu ◽  
Bo Li ◽  
Hao Wang ◽  
Kun Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Strong Wind ◽  
Transmission Tower ◽  
Element Analysis ◽  
Straight Line ◽  
The Finite Element Analysis

Put the finite element analysis of line tower coupling modeling to the collapse of a 110 kV line straight-line tower, study the effect of strong wind on transmission tower and wire. The results show that under the action of strong wind, the material specification selected by the part of the rods on the type of tower is lower, cross section is smaller, the principal material of tower will be instable and flexional under the compression, resulting in tower collapsed.

scholarly journals Viscoelastic analysis of Calving Glaciers

1980 ◽  
Vol 1 ◽  
pp. 37-41 ◽  
Author(s):  
D. V. Reddy ◽  
W. Bobby ◽  
M. Arockiasamy ◽  
R. T. Dempster
Keyword(s):  
Finite Element ◽  
Sea Water ◽  
Water Pressure ◽  
Computer Code ◽  
Ice Shelf ◽  
Element Analysis ◽  
Ice Shelves ◽  
Shear Moduli ◽  
Relaxation Functions ◽  
Spring Force

Calving of floating ice shelves is studied by a viscoelastic finite-element analysis. The fan-shaped breaking-up of glaciers due to forces that cause bending on creeping ice is assumed to be axisymmetric. Bending may be due to geometry of the bcdrock, action of tides and waves, and imbalance (at the ice front) between the stress in the ice and the sea-water pressure.The bulk and shear moduli of the ice are represented by relaxation functions of the Prony series, which is a discrete relaxation spectrum composed of a constant and a summation of exponential terms. These properties are also functions of temperature, that varies over the thickness of the ice shelf. The temperature distribution across the thickness of the ice is obtained from calculations based on a linear dependence of thermal conductivity on the temperature. Numerical results are presented for various calving mechanisms. A computer code, VISIC1, is developed by modifying a finite-element viscoelastic code, VISICE, for floating ice islands. The buoyancy of the water is taken into account by a Winkler spring model, with the spring force determined from displaced volume. Locations of crack initiation obtained from the analysis are used to predict the iceberg size immediately after calving.

scholarly journals Investigation of the Prediction Accuracy of a Finite Element Analysis Model for the Coating Thickness in Cross-Wedge Rolled Coaxial Hybrid Parts

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2969 ◽  
Author(s):  
Jagodzinski ◽  
Kruse ◽  
Barroi ◽  
Mildebrath ◽  
Langner ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Coating Thickness ◽  
Wedge Angle ◽  
Research Centre ◽  
Cross Wedge Rolling ◽  
Element Analysis ◽  
Hybrid Parts ◽  
Experimental Trials

The Collaborative Research Centre 1153 (CRC 1153) “Process chain for the production of hybrid high-performance components through tailored forming” aims to develop new process chains for the production of hybrid bulk components using joined semi-finished workpieces. The subproject B1 investigates the formability of hybrid parts using cross-wedge rolling. This study investigates the reduction of the coating thickness of coaxially arranged semi-finished hybrid parts through cross-wedge rolling. The investigated parts are made of two steels (1.0460 and 1.4718) via laser cladding with hot-wire. The rolling process is designed by finite element (FE)-simulations and later experimentally investigated. Research priorities include investigations of the difference in the coating thickness of the laser cladded 1.4718 before and after cross-wedge rolling depending on the wedge angle β, cross-section reduction ∆A, and the forming speed ν. Also, the simulations and the experimental trials are compared to verify the possibility of predicting the thickness via finite element analysis (FEA). The main finding was the ability to describe the forming behavior of coaxially arranged hybrid parts at a cross-section reduction of 20% using FEA. For a cross-section reduction of 70% the results showed a larger deviation between simulation and experimental trials. The deviations were between 0.8% and 26.2%.

Study on Mechanics Properties of Automobile Rear Axle Shell and Optimization Design in Manufacturing System

2012 ◽  
Vol 252 ◽  
pp. 298-301
Author(s):  
Xin Li Bai ◽  
Ying Fang Zhang ◽  
Ya Wei Zhao
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Optimization Design ◽  
Manufacturing System ◽  
Rear Axle ◽  
Large Strain ◽  
Displacement Curve ◽  
Original Design ◽  
Load Curve ◽  
Element Analysis

The mechanics properties of a certain automobile rear axle shell were studied and a large displacement, large strain elastoplastic finite element analysis was carried out. and the followings were obtained: the load-displacement curve at loading point, elastoplastic strain-load curve at the maximum stress point, elastoplastic stress-load curve in dangerous cross-section, and the yielding load at which the dangerous cross-section overall yield. The results show that elastoplastic finite element simulation results are much closer to the experimental corresponding results. Through optimization design in manufacturing system, the weight of the rear axle shell is greatly reduced as compared with the original design. Optimal design not only saves materials and reduces cost, but also greatly reduces the design time. The calculation results provide the necessary data for automobile rear axle design, strength evaluation and fatigue life estimate.

Shape Optimization Study of Mild Steel Slit Dampers

2010 ◽  
Vol 168-170 ◽  
pp. 2434-2438 ◽  
Author(s):  
Yan Hong Xu ◽  
Ai Qun Li ◽  
Xing De Zhou ◽  
Peng Sun
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Cross Section ◽  
Design Method ◽  
Elastic Stiffness ◽  
Displacement Curve ◽  
Element Analysis ◽  
Optimization Study ◽  
Maximal Stress ◽  
Yield Displacement

This paper presented a new mild steel slit damper(SSD). The new shape was parabolic according to all the cross section having the same maximal stress, and the elastic stiffness and yield displacement formula were derived. Finite element analysis showed that the parabolic shaped damper had a more reasonable load - displacement curve compared with the previously proposed shape. The theoretical stiffness and yield displacement were consistent with the results by finite element method (FEM), and that indicated the presented design method was simple and feasible.

Fatigue Evaluation of Flat Steel Box Girders with Closed Stiffeners of Large-Span Suspension Bridges under Different Heavy Trucks

2011 ◽  
Vol 147 ◽  
pp. 157-160 ◽  
Author(s):  
Yong Zeng ◽  
Hong Mei Tan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cross Section ◽  
Suspension Bridges ◽  
Box Girders ◽  
Element Analysis ◽  
Box Girder ◽  
Fatigue Assessment ◽  
Steel Box Girder ◽  
Flat Steel

Due to its outstanding aerodynamic shape and light weight, the trapezoidal cross-section flat steel box girder with orthotropic decks and thin-walled longitudinal stiffeners of trapezoidal cross section are widely used in long-span suspension bridges in the world. However, because of the geometrical characteristics and the relative flexibility of their components, these structures may be quite susceptible to traffic loadings that fatigue cracks tend to appear in these structures. In this paper, Jiangyin Bridge is used as a case study to investigate the fatigue performance of the steel girders of suspension bridge Jiangyin Bridge is the second longest bridge in China, which has the main span of 1385m. The stress analysis of steel box girders is firstly carried out based on the analysis of fatigue life. Fatigue assessment method is proposed on the basis of in-situ measurement data combined with finite element analysis. A complete fatigue assessment is made in this paper. Key words: flat steel box girder; orthotropic decks; finite element analysis; fatigue assessment

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