scholarly journals An Analytical Model of Strength Loss in Filament Wound Spherical Vessels

1987 ◽  
Vol 109 (3) ◽  
pp. 352-356 ◽  
Author(s):  
P. J. Leavesley ◽  
C. E. Knight
Keyword(s):  
Finite Element ◽  
Compressive Strain ◽  
Strength Loss ◽  
Element Model ◽  
Strength Degradation ◽  
Thick Wall ◽  
Finite Element Program ◽  
Thickness Profile ◽  
Filament Wound ◽  
Incremental Construction

The potential strength degradation of a filament wound sphere was predicted using an incremental finite element model of the composite during fabrication. The sphere was modeled taking into account the winding pattern and the resulting internal layer boundaries. The thickness profile of the sphere’s layers were computed using a pattern simulation program. The total thickness profile and layer thickness profiles were used by the mesh generating program to ensure that the elements generated matched layer boundaries. The elements were isoparametric quadrilaterals which were collapsed to triangular elements for transitions. The main feature of the finite element program was the incremental construction and loading of the model to simulate the winding process. Strength degradation definitely occurs when the average fiber strain in any layer is negative. The negative strain means that all the winding tension has been lost from the layer, and the imposition of compressive strain causes fibers in uncured resin to wrinkle or buckle. Then when the resin cures the buckled region of fibers are degraded in strength. An analysis of a Kevlar/epoxy sphere demonstrated that strength degradation could occur. The innermost layers showed significant tension loss and compressive strain during fabrication which would produce strength degradation. The model sphere was a typical thick wall construction using normal processing conditions.

Study on Crashworthiness Characteristics of Several Concentric Thin Wall Tubes

2010 ◽  
Author(s):  
Parisa Hosseini Tehrani ◽  
Sajad Pirmohammad
Keyword(s):  
Finite Element ◽  
Optimum Combination ◽  
Thick Wall ◽  
Thin Wall ◽  
Finite Element Program ◽  
Linear Dynamic ◽  
Wall Structures ◽  
Moving Body ◽  
Oblique Loading ◽  
Element Program

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.

Static and Dynamic Analyses of the LSES Hull Structure

1978 ◽  
Vol 22 (02) ◽  
pp. 110-122
Author(s):  
A. S. Hananel ◽  
E. J. Dent ◽  
E. J. Philips ◽  
S. H. Chang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Surface Effect ◽  
Three Dimensional ◽  
Element Model ◽  
Finite Element Program ◽  
Hull Structure ◽  
Surface Effect Ship ◽  
Hull Design ◽  
Element Program

To avoid the conservativeness in the large surface-effect ship hull design which results from simplifying assumptions in the stress analysis, the hull structure was analyzed as a three-dimensional elastic body. The NASTRAN finite-element program, level 15.0, was selected for use in this analysis as the most suitable program available. A finite-element model representing the true hull stiffness was used in obtaining the internal load and displacement distributions. The inertia effect of the ship masses was included with each set of static loads. This was done by using the Static Analysis with Inertia Relief solution included in NASTRAN. The stress redistribution around cutouts in the hull was treated in a separate study. The interaction between hull and deckhouse was investigated by attaching a model of the deckhouse onto the hull model, and then solving for the appropriate load conditions. The natural frequencies were obtained using a reduced finite-element model of both the hull and hull/deckhouse combination. A new technique was developed for determining the dynamic stresses and their proper superposition on the static stresses.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2018 ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Volkan Coşkun ◽  
Bülent Acar ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Layer Thickness ◽  
Pressure Vessel ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture the pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition and material properties of matrix and fiber. The designed ideal pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, the effect of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance was investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the layer-by-layer thickness and fiber volume fraction variation. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization test was performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

Virtual Testing for Frontal Impact of High-Top Cab of Heavy Truck

2011 ◽  
Vol 148-149 ◽  
pp. 1081-1084
Author(s):  
Wei Wang ◽  
Xu Liang Xie ◽  
Fu Lin Shen ◽  
Xiao Feng Wang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Front Seat ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Commercial Code ◽  
Element Program ◽  
Heavy Truck ◽  
Survival Space ◽  
Pendulum Impact

ECE R29 regulation has legally claimed that the survival space must be guaranteed for the safety for driver and front seat passenger in event of crash during design of truck cabin. In this paper, a finite element model of a high-top cabin of a heavy truck with a manikin on the driver seat was built with commercial code Hypermesh, The explicit finite element program Ls-Dyna was used to simulate the frontal pendulum impact on the high-top cab in the light of ECE R29 regulation. Deformation of the truck cabin and the survival space of the dummy were analyzed and discussed. Also, some suggestions were given to solve the contact possibility between steering column and the knees of manikin.

The Effects of Layer-by-Layer Thickness and Fiber Volume Fraction Variation on the Mechanical Performance of a Pressure Vessel

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Emre Özaslan ◽  
Ali Yetgin ◽  
Bülent Acar ◽  
Volkan Coşkun ◽  
Tarık Olğar
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Material Properties ◽  
Fiber Volume Fraction ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Element Model ◽  
Layer By Layer ◽  
Fiber Volume ◽  
Filament Wound

Abstract Due to high stiffness/weight ratio, composite materials are widely used in aerospace applications such as motor case of rockets which can be regarded as a pressure vessel. The most commonly used method to manufacture pressure vessels is the wet filament winding. However, the mechanical performance of a filament wound pressure vessel directly depends on the manufacturing process, manufacturing site environmental condition, and material properties of matrix and fiber. The designed pressure vessel may not be manufactured because of the mentioned issues. Therefore, manufacturing of filament wound composite structures are based on manufacturing experience and experiment. In this study, effects of layer-by-layer thickness and fiber volume fraction variation due to manufacturing process on the mechanical performance were investigated for filament wound pressure vessel with unequal dome openings. First, the finite element model was created for designed thickness dimensions and constant material properties for all layers. Then, the model was updated. The updated finite element model considered the thickness of each layer separately and variation of fiber volume fraction between the layers. Effects of the thickness and fiber volume fraction on the stress distribution along the motor axial direction were shown. Also hydrostatic pressurization tests were performed to verify finite element analysis in terms of fiber direction strain through the motor case outer surface. Important aspects of analyzing a filament wound pressure vessel were addressed for designers.

scholarly journals Evaluation of Strains at the Bottom of the Asphalt Base Layer of a Semi-Rigid Pavement Under a Class 6 Vehicle

2019 ◽  
Vol 271 ◽  
pp. 08008
Author(s):  
Mohsen Talebsafa ◽  
Stefan A. Romanoschi ◽  
Athanassios T. Papagiannakis ◽  
Constantin Popescu
Keyword(s):  
Finite Element ◽  
Longitudinal Direction ◽  
Element Model ◽  
Base Layer ◽  
Rigid Pavement ◽  
Finite Element Program ◽  
Element Program ◽  
Transverse Strains ◽  
Longitudinal Strains ◽  
Good Agreement

A newly constructed pavement on US-287 near Mansfield, TX was instrumented with gauges installed at the bottom of the asphalt concrete base layer to measure the longitudinal and transverse strains developed under a test vehicle. The finite element program Abaqus was used to compute the strains at the location of the gauges; they were found in good agreement with the measured strains. The research showed that the strains under the steering axle were of similar magnitude as the strains under the rear tandem axle. The measured transverse strains were in general slightly bigger than the corresponding longitudinal strains, while the finite element model computed higher strains in the longitudinal direction. These findings suggest the need to account for the strain responses from the steering axle of trucks and to account for both the longitudinal and the transverse strains when computing the fatigue damage induced by trucks.

Stress Analysis of Pin-Loaded Composite Plates

2004 ◽  
Author(s):  
James J.-S. Stone ◽  
Shen-Haw Ju ◽  
Robert E. Rowlands
Keyword(s):  
Finite Element ◽  
Frictional Contact ◽  
Composite Plates ◽  
High Sensitivity ◽  
Element Model ◽  
Bolted Joint ◽  
Numerical Techniques ◽  
Considerable Effort ◽  
Finite Element Program ◽  
Element Program

The frictional contact of the pin-loaded joint in composite plates was studied. This included the effects of pin clearance and variations in material and geometry. Full-filed displacements were measured by high sensitivity moire´ interferometry. Considerable effort was expended to develop a loading frame, relevant fixtures and monitoring capability to ensure that the plate was loaded uniformly through its thickness, particularly at the pin-loaded hole. Numerical techniques were prepared for processing the optical fringe data. A reliable finite element model for a bolted joint was also formulated. The efficient finite element program, which is capable of handling friction and/or clearance at the loaded hole, has been validated analytically, experimentally and numerically.

Numerical Testing for Roof Strength and Rear Wall Strength of High-Top Heavy Truck Cab

2011 ◽  
Vol 148-149 ◽  
pp. 198-201
Author(s):  
Wei Wang ◽  
Xu Liang Xie ◽  
Fu Lin Shen ◽  
Xiao Feng Wang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Strength Analysis ◽  
Rear Wall ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Wall Strength ◽  
Heavy Truck ◽  
Roof Strength ◽  
Survival Space

For design of truck cabin, the survival space must be guaranteed for the safety for driver and front seat passenger in event of crash, which is the legal requirement described in ECE-R29 regulation. In this paper, a finite element model of a high-top cabin for heavy truck was built with commercial code Hypermesh, and a manikin according to ECE-R29 was added to the driver seat. The explicit finite element program Ls-Dyna was used to verify the roof strength and rear wall strength. Analysis and discussion on the deformation of the truck cabin and the survival space of the dummy were presented. The survival space of the cab was proved to be sufficient for the safety of the driver.

Finite Element Analysis of Synchronous Belt Tooth Failure

1993 ◽  
Vol 207 (2) ◽  
pp. 145-153 ◽  
Author(s):  
K W Dalgarno ◽  
A J Day ◽  
T H C Childs
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Model ◽  
Element Model ◽  
Element Analysis ◽  
Finite Element Program ◽  
Interface Elements ◽  
Dimensional Finite Element ◽  
Element Program ◽  
Critical Strains

This paper describes a finite element analysis of a synchronous belt tooth under operational loads and conditions with the objective of obtaining a greater understanding of belt failure by tooth root cracking through an examination of the strains within the facing fabric in the belt. The analysis used the ABAQUS finite element program, and was based on a two-dimensional finite element model incorporating a hyperelastic material model for the elastomer compound. Contact between the belt tooth face and the pulley groove was modelled using surface interface elements which allowed only compression and shear forces at the contact surfaces. It is concluded that the critical strains in the facing fabric of the belt, and therefore the belt life, are largely determined by the tangential loading condition on the belt teeth.

Finite Element Analysis of a Close Head Axonal Injury Model: Relating Brain Tissue Biomechanics to Skull Deformation

2008 ◽  
Author(s):  
Haojie Mao ◽  
Liying Zhang ◽  
King H. Yang ◽  
Albert I. King ◽  
J’ozsef Pál ◽  
...  
Keyword(s):  
Finite Element ◽  
Compressive Strain ◽  
Axonal Injury ◽  
Element Model ◽  
Element Analysis ◽  
Injury Model ◽  
Weight Drop ◽  
Biomechanical Responses ◽  
Histological Results ◽  
The Impact

Biomechanical responses of a rat brain in a new weight-drop model were investigated by comparing histological results against finite element model predictions. This graded axonal injury rat model differed from others because of its utilization of intact skull without global angular motion to confound data analyses. Results demonstrated that the maximum principal strain and the compressive strain along the impact direction best correlated the experimentally observed injury locations while the shear strain did not have positive correlation.

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