Redesign of Spherical Acrylic Submersible for Manned Operation to 3000 ft (914.4 m) Ocean Depth

2000 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Finite Element Analysis ◽  
Cyclic Fatigue ◽  
Relative Displacement ◽  
Design Guidelines ◽  
Shear Cracks ◽  
Two Phase ◽  
Element Analysis ◽  
Ocean Exploration ◽  
Manned Submersible ◽  
Generation Problem

Abstract Harbor Branch Oceanographic Institution (HBOI) is using its spherical acrylic manned submersible for ocean exploration for last 3 decades. However, the development of tiny shear cracks at the interface areas of these submersibles following only few hundred dives require frequent, expensive repairs. To overcome this crack generation problem, a two-Phase research program is initiated at HBOI. In the Phase I of this study, a detailed nonlinear 3-D Finite Element Analysis (FEA) is performed at first to increase the understanding of the mechanical behavior at the interface of this submersible and then various analyses are carried out to develop a guidelines for redesigning the spherical acrylic submersible. Complete redesigning of the bottom of acrylic submersible is only presented here in details, as the discussion on the top of acrylic submersible is presented earlier. Based on the new design guidelines, in the Phase II of this study, a new spherical acrylic submersible is fabricated at HBOI. Brief discussion of the experimental results on the new submersible is also presented here. A significant reduction in peak stresses and a very small relative displacement at the gasket/acrylic interface which are believed to be two of the main causes for crack development at the interface areas clearly indicate a major improvement in the new design of the acrylic submersible, as they are also suggested by the extensive FEA results. This improvement in design is expected to extend the crack free cyclic fatigue life of the acrylic submersible at 3000 ft (914.4 m) ocean depth significantly.

Redesign of NEMO-Type Spherical Acrylic Submersible for Manned Operation to 3000 ft (914 m) Ocean Depth

2001 ◽  
Vol 124 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Dissimilar Materials ◽  
Cyclic Fatigue ◽  
Design Guidelines ◽  
Element Analysis ◽  
Design Guideline ◽  
Crack Generation ◽  
Generation Problem

A detailed nonlinear three-dimensional (3-D) finite element analysis (FEA) was performed in Phase I on a NEMO (naval experimental manned observatory) type HBOI (Harbor Branch Oceanographic Institution) spherical acrylic submersible in order to overcome the crack generation problem at its interfaces. An FEA has been carried out to develop a new design guideline, by reducing the higher stresses and relative displacements at the interfaces, which are believed to be two of the main reasons for crack generation at these areas. Variation of the stiffness between dissimilar materials at the interface, lower nylon gasket thickness, overdesigned aluminum hatch and bottom penetrator plug, attachment of the retainer ring with hatch ring, close placement of the rubber padding to the interface between the acrylic sphere, and the retainer ring are found to be the various causes for higher stresses within the acrylic sphere at the nylon gasket/acrylic interface. Based on the new design guidelines, in Phase II, a new spherical acrylic submersible was fabricated and tested. This design resulted in significant improvements by reducing the peak stresses and relative displacements at the gasket/acrylic interface areas. This improvement in design is expected to significantly extend the crack-free cyclic fatigue life of the acrylic submersible at 3000 ft (914 m) ocean depth.

scholarly journals A NONLINEAR FINITE ELEMENT ANALYSIS OF PRECAST INDUSTRIALISED BUILDING SYSTEM BEAM UNDER FLEXURAL TEST

2019 ◽  
Vol 81 (3) ◽  
Author(s):  
Chun-Chieh Yip ◽  
Jing-Ying Wong ◽  
Ka-Wai Hor
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beam ◽  
Failure Modes ◽  
Reinforced Concrete Beam ◽  
Shear Cracks ◽  
Flexural Test ◽  
Element Analysis ◽  
Failure Behaviour

Software simulation enables design engineers to have a better picture of possible structural failure behaviour and determine the accuracy of a design before the actual structural component is fabricated. Finite element analysis is used to simulate the behaviour of the reinforced concrete beam under the flexural test. During the flexural test, results are recorded for both simulation and experimental tests. By comparing the results, beam displacement, crack patterns, and failure modes can be studied with better accuracy. The accuracy percentage for yield load and ultimate load between the two tests results were 94.12 % and 95.79 %, respectively, whereas the accuracy percentage for elastic gradient before the yielding stage was 81.08 %. The behaviour between simulation and laboratory models described is based on crack pattern and failure mode. The progression of von Mises (VM) stresses highlighted the critical areas of the reinforced concrete beam and correlation between the experimental specimen, in terms of flexural cracks, shear cracks, yielding of tension reinforcement, and the crushing of concrete due to compressive stress. This paper concludes that simulation can achieve a significant accuracy in terms of loads and failure behaviour compared to the experimental model.

scholarly journals Two-Phase Linear Hybrid Reluctance Actuator with Low Detent Force

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5162
Author(s):  
Jordi Garcia-Amorós ◽  
Marc Marín-Genescà ◽  
Pere Andrada ◽  
Eusebi Martínez-Piera
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Permanent Magnets ◽  
Thrust Force ◽  
Experimental Tests ◽  
Force Density ◽  
Two Phase ◽  
Element Analysis ◽  
Switched Reluctance ◽  
Detent Force

In this paper, a novel two-phase linear hybrid reluctance actuator with the double-sided segmented stator, made of laminated U cores, and an interior mover with permanent magnets is proposed. The permanent magnets are disposed of in a way that increases the thrust force of a double-sided linear switched reluctance actuator of the same size. To achieve this objective, each phase of the actuator is powered by a single H-bridge inverter. To reduce the detent force, the upper and the lower stator were shifted. Finite element analysis was used to demonstrate that the proposed actuator has a high force density with low detent force. In addition, a comparative study between the proposed linear hybrid reluctance actuator, linear switched reluctance, and linear permanent magnet actuators of the same size was performed. Finally, experimental tests carried out in a prototype confirmed the goals of the proposed actuator.

scholarly journals The Finite Element Analysis for a Mini-Conductance Probe in Horizontal Oil-Water Two-Phase Flow

Sensors ◽  
2016 ◽  
Vol 16 (9) ◽  
pp. 1352 ◽  
Author(s):  
Weihang Kong ◽  
Lingfu Kong ◽  
Lei Li ◽  
Xingbin Liu ◽  
Ronghua Xie ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Conductance Probe ◽  
Oil Water

Moisture Content's Influence to Pile Bearing Capacity and Finite Element Analysis

2014 ◽  
Vol 633-634 ◽  
pp. 922-926
Author(s):  
Li Hua Zhang ◽  
Li Yu ◽  
Zhe Jun Quan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Moisture Content ◽  
Bearing Capacity ◽  
Unsaturated Soil ◽  
Vertical Displacement ◽  
Relative Displacement ◽  
Engineering Practice ◽  
Element Analysis ◽  
Lateral Extrusion

This essay analyzes stress between pile and soil, occupying moisture content data of unsaturated soil in Nanchang with ANSYS. In accordance with engineering practice, it adopts three-dimensional solid model, the same geometric size with engineering practice. It simulates interrelation between pile and soil with contact unit, and shows ontology relation of soil with D-P elastic-plastic model. Convergence has been made with selection and calculation of parameter. The greater the moisture content gets, the smaller the pile body vertical displacement makes. In other words, the smaller the relative displacement between pile and soil gets, the lower the lateral extrusion stress from pile to soil becomes. Keywords: unsaturated soil; shear strength; pile bearing capacity; finite element analysis; moisture content

Shape Optimization of a Small Bus Steering Knuckle Considering a Fatigue Load

2013 ◽  
Vol 740 ◽  
pp. 319-322 ◽  
Author(s):  
Young Choon Lee ◽  
Nam Jin Jeon ◽  
Cheol Kim ◽  
Seo Yeon Ahn ◽  
Myung Jae Cho
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Shape Optimization ◽  
Minimum Weight ◽  
Cyclic Fatigue ◽  
Fatigue Load ◽  
Element Analysis ◽  
Gradient Based

Finite element analysis was accomplished for a steering knuckle component of a small bus to see whether the static and fatigue strength requirements were satisfied or not. The knuckle was modeled with ANSYS 10-node quadratic elements. The cyclic fatigue load was applied and Soderberg criteria were applied to check the fatigue life. The knuckle structure has an infinite life (10-6 cycle) judging from the fatigue analyses. Shape optimization based on the gradient based method has been performed in order to find out the knuckle shape that has a minimum weight and satisfies the static and fatigue strength requirements. As a result of shape optimization, the weight of the steering knuckle was reduced 8%.

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