Flanged Acrylic Plastic Hemispherical Shells for Undersea Application

1975 ◽  
Vol 97 (1) ◽  
pp. 1-9 ◽  
Author(s):  
J. D. Stachiw ◽  
J. R. Maison
Keyword(s):  
Finite Element ◽  
Hydrostatic Pressure ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Critical Pressure ◽  
Convex Surface ◽  
Elastic Analysis ◽  
Short Term ◽  
Acrylic Plastic ◽  
Hemispherical Shells

The effects of an equatorial flange and a nonuniform wall thickness upon the critical pressure and stress distribution in acrylic plastic hemispheres have been investigated by experimental and analytical methods. Forty acrylic hemispheres were fabricated and tested to destruction under short term hydrostatic pressure applied on the convex surface. Dome apex displacements were obtained from each specimen and strains were obtained from a selected few. A finite element elastic analysis was performed on one window configuration for two different boundary conditions and the experimentally derived stresses were used to determine which boundary conditions was the best for analytical analysis.

General Instability of Stiffened Circular Conical Shells under Hydrostatic Pressure

1965 ◽  
Vol 16 (2) ◽  
pp. 187-204 ◽  
Author(s):  
M. Baruch ◽  
J. Singer
Keyword(s):  
Hydrostatic Pressure ◽  
Boundary Conditions ◽  
Cross Section ◽  
Contact Surface ◽  
Critical Pressure ◽  
Boundary Work ◽  
Conical Shells ◽  
Circular Conical Shells ◽  
Simple Supports ◽  
The Stability

SummaryDonnell type equilibrium and stability equations are derived for stiffened thin conical shells. The stiffeners are considered closely spaced and are therefore assumed to be “distributed” over the whole surface of the shell. In the proposed theory the stiffeners and their spacing may vary in any prescribed manner, but here only equal and equally spaced stiffeners are dealt with. The force- and moment-strain relations of the combined stiffener-sheet cross section are determined by the assumption of identical normal strains at the contact surface of stiffener and sheet.The stability equations are solved for general instability under hydrostatic pressure by the method of virtual displacements. The solution used earlier for unstiffened conical shells, which satisfies some of the boundary conditions of simple supports only approximately, is again applied here. The effect of this incomplete compliance with boundary conditions is shown to be negligible by consideration of “boundary work”. The solution proposed for stiffened conical shells involves the concepts of “correcting coefficients” and minimisation of corresponding “error loads”.Typical examples are analysed and the effect of eccentricity of stiffeners is investigated. Simplified approximate formulae for the critical pressure of frame-stiffened conical shells are also proposed.

The Elastic Analysis of Finite Element to the Shell of Blast Furnace under Thermal - Structural Coupling

2011 ◽  
Vol 368-373 ◽  
pp. 1495-1499
Author(s):  
Shan Hua Xu ◽  
Xin Long Yang ◽  
Jian Li ◽  
Bin Shi ◽  
Bin Qiu
Keyword(s):  
Finite Element ◽  
Blast Furnace ◽  
Stress Distribution ◽  
Great Influence ◽  
Elastic Analysis ◽  
Elastic State ◽  
Blast Furnaces ◽  
Structural System ◽  
Structural Coupling ◽  
Temperature Loads

Stress distribution of blast furnace shell is important to the security of structural system. According to real loads of blast furnace and temperature loads, this paper carries on the analysis of elastic finite element to a blast furnaces utilizing the software ANSYS. The result shows that most areas of the blast furnace are in elastic state, and only a few around holes are in plasticity state as the result of stress concentration; temperature loads have great influence over the structure stress and displacement. We obtain the stress distribution of blast furnace that is useful in the design of subsequent blast furnace.

Spherical Shell Sector Acrylic Plastic Windows with 12,000 ft Operational Depth for Submersible Alvin

1976 ◽  
Vol 98 (2) ◽  
pp. 523-536 ◽  
Author(s):  
J. D. Stachiw ◽  
R. Sletten
Keyword(s):  
Stress Distribution ◽  
Spherical Shell ◽  
Critical Pressure ◽  
Catastrophic Failure ◽  
Ocean Bottom ◽  
Uniform Stress ◽  
Short Term ◽  
Single Pass ◽  
Sustained Loading ◽  
The Cost

It has been found that the 90-deg plane conical frustum windows with t/Di = 0.7 ratio in ALVIN submersible can be replaced with 90-deg t/Di = 1 spherical shell sector windows without any modification of window seat flanges. The 90-deg spherical shell sector windows with t/Di = 1.0 possess not only a higher short term critical pressure but also develop more uniform stress distribution during a typical dive to 12,000 ft than the t/Di = 0.7 acrylic conical frustum windows that they replace. The 90-deg t/Di = 1.0 spherical shell sector windows (1) withstood, without catastrophic failure, 100 hr sustained loading to 20,000 psi, (2) 33 pressure cycles of 7-hr duration to 13,500 ft depth without any signs of fatigue, and (3) experienced less than 15,000 μin. strain during a simulated typical prooftest dive to 13,500 ft depth. The 90-deg t/Di = 1 spherical shell sector window presents a 50 percent larger view in water than a 90-deg t/Di = 0.7 conical frustum window that it replaces. This permits the observer inside the submersible to cover visually more ocean bottom during a single pass along the bottom and thus decreases the cost of a typical bottom search mission for a submersible.

scholarly journals Modeling and Thermal-Mechanical Coupling Analysis of Piston in Car Engines

2020 ◽  
Vol 45 (1) ◽  
pp. 83-92
Author(s):  
Feifei Zhao
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Stress Distribution ◽  
Stress Field ◽  
Boundary Conditions ◽  
Thermal Load ◽  
Mechanical Load ◽  
Field Analysis ◽  
Coupling Analysis ◽  
Mechanical Coupling

In this paper, finite-element analysis (FEA) is carried out on the temperature field and stress field of automobile engine piston, as well as the thermal-mechanical load coupling stress field. Through the analysis, the authors grasped the thermal load and combined stress distribution of the piston, and thus optimized the piston design to improve its operational reliability. Specifically, a 1/4 solid model of the piston was constructed in the three-dimensional (3D) computer-aided design (CAD) software Pro/ENGINEER, and then converted into a finite-element model in Pro/Mechanica. Then, an alternating load was imposed on the piston model, and fatigue analysis was performed to identify the parts of the piston prone to fatigue failure, and judge whether the piston structure satisfies working requirements. Next, temperature field analysis was carried out on the piston model. The distribution of the steady-state temperature field as determined by applying temperatures and heat transfer coefficients as required by the boundary conditions of the third kind. Finally, the piston model was subject to thermal-mechanical coupling analysis. The stress and deformation distributions of the piston under the coupled stress field were ascertained under the boundary conditions of temperature field distribution and mechanical load. Through the above work, the authors obtained the basis for safety evaluation of piston, laying the foundation for further reducing the thermal load and optimizing the stress distribution of piston.

Spherical Acrylic Pressure Hulls With Multiple Penetrations

1978 ◽  
Vol 100 (2) ◽  
pp. 261-271 ◽  
Author(s):  
J. D. Stachiw ◽  
R. B. Dolan
Keyword(s):  
Hydrostatic Pressure ◽  
Structural Response ◽  
Structural Performance ◽  
Experimental Program ◽  
External Hydrostatic Pressure ◽  
Short Term ◽  
Acrylic Plastic ◽  
Model Scale ◽  
Depth Rating

An experimental program has been conducted to determine the effect of multiple penetrations on the performance of spherical acrylic plastic hulls under external hydrostatic pressure. As test specimens served 15-in. OD × 14-in. ID model scale NEMO spheres. The distribution of strains and the magnitudes of short term critical pressures indicate that the structural response of acrylic spheres with multiple penetrations to external hydrostatic pressure is identical to spheres with only one penetration equipped with a metallic closure providing that the included angles of the penetrations are ≤46 deg and the edges of the penetrations are at least one penetration radius apart. Based on these findings it is feasible to incorporate three or more large penetrations into the spherical hulls of acrylic submersibles without decreasing their operational depth rating that has been based on the experimentally proven structural performance of spheres with only one penetration, or two penetrations 180 deg center to center apart.

A Novel Dynamic Bone Stress Evaluation Method of Postoperative Proximal Femur During Gait by Using Elastic Multi Body Analysis Based on Finite Element Analysis

2017 ◽  
Author(s):  
Yukiko Nakamura ◽  
Kazuhiko Adachi ◽  
Nungna Wi ◽  
Mitsuaki Noda
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Hip Joint ◽  
Proximal Femur ◽  
Dynamic Stress ◽  
Fe Analysis ◽  
Patient Specific ◽  
Time Varying ◽  
Multi Body

A proximal femur fracture due to osteoporosis is one of serious health care problems in aging societies. Osteosynthesis with pin or screw type of implants, such as Hansson pin (HP), Dual SC Screw (DSCS), is widely used for femoral neck fracture treatment in Japan. Unfortunately, some complications such as secondary fractures, especially peri-prosthetic fractures, may occur during postoperative rehabilitation period. In order to reveal the potential cause of the postoperative fracture from the viewpoint of the biomechanics, authors had already performed the dynamic stress analysis of the treated proximal femur based on finite element (FE) analysis. The final goal of our project is to establish the reliable postoperative bone fracture risk assessment method in response to the daily activity including mainly walking. The aim of this study is to propose a novel elastic multi body analysis method based on FE analysis for proximal femur biomechanics. Patient-specific 3D left hip joint FE model was constructed from an elderly female volunteer’s CT images. The model consists of the pelvis, proximal femur, cartilage and DSCS, as multi bodies. The dynamic loading and boundary conditions were applied to the model for simulating a gait motion. Direction and magnitude of the loads varies in response to the gait motion. The time dependent loading forces; hip contact, gluteus medius, gluteus maximus, tensor fasciae latae and adductor, acting around the hip joint was obtained by inverse dynamic analysis of a human gait using in-house lower-limb musculoskeletal model. These loading and boundary conditions for simulating the gait motion are the major technical advantages of the proposed multi body analysis comparing with the conventional static FE analysis. Time varying stress distribution during the gait was evaluated by using dynamic explicit method via ABAQUS. In order to visually demonstrate dynamic stress distribution, we examined the time varying von Mises stresses at the representative points located on the cortical surface of the proximal femur; femoral head, fracture surface and around the lateral insertion holes. The results indicate significant increase of the stresses around the proximal lateral insertion holes for DSCS treatment. Maximum stress values are good agreement with the previous static FE analysis, on the other hand, these biomechanical discussions based on the stress time histories are only obtained from the proposed method. It is indicated that the proposed method is feasible to support the better pre- and postoperative clinical decisions, which is the main contribution of this study.

Vibrations of an Incompressible Linearly Elastic Plate Using Discontinuous Finite Element Basis Functions for Pressure

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Lisha Yuan ◽  
Romesh C. Batra
Keyword(s):  
Finite Element ◽  
Hydrostatic Pressure ◽  
Boundary Conditions ◽  
Plate Theory ◽  
Mass Matrix ◽  
Basis Functions ◽  
Mode Shapes ◽  
Normal Strain ◽  
Simply Supported ◽  
Transverse Normal Strain

Abstract We numerically analyze, with the finite element method, free vibrations of incompressible rectangular plates under different boundary conditions with a third-order shear and normal deformable theory (TSNDT) derived by Batra. The displacements are taken as unknowns at the nodes of a 9-node quadrilateral element and the hydrostatic pressure at four interior nodes. The plate theory satisfies the incompressibility condition, and the basis functions satisfy the Babuska-Brezzi condition. Because of the singular mass matrix, Moler's QZ algorithm (also known as the generalized Schur decomposition) is used to solve the resulting eigenvalue problem. Computed results for simply supported, clamped, and clamped-free rectangular isotropic plates agree well with the corresponding analytical frequencies of simply supported plates and with those found using the commercial software, abaqus, for other edge conditions. In-plane modes of vibrations are clearly discerned from mode shapes of square plates of aspect ratio 1/8 for all three boundary conditions. The magnitude of the transverse normal strain at a point is found to equal the sum of the two axial strains implying that higher-order plate theories that assume null transverse normal strain will very likely not provide good solutions for plates made of rubberlike materials that are generally taken to be incompressible. We have also compared the presently computed through-the-thickness distributions of stresses and the hydrostatic pressure with those found using abaqus.

Strength Analysis of Corn Combine Harvester Chassis

2014 ◽  
Vol 644-650 ◽  
pp. 489-492
Author(s):  
Dong Fang Hu ◽  
Yan Ping Du
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Strength Analysis ◽  
Quality And Safety ◽  
Analysis Software ◽  
Element Analysis ◽  
Combine Harvester ◽  
Quality And Reliability

As the installed base of all other assemblies, the corn combine harvester chassis supports a variety of loads from the harvester and ground, so its reliability directly affects the quality and safety of the corn combine harvester. The analysis of corn combine harvester chassis was carried out with finite element analysis software. First, the 3D part of the chassis was established and simplified in accordance with the relevant principles. Second, the stress distribution and displacement of the chassis in the no-loaded and full-loaded conditions were calculated by meshing,applying loads and constraining boundary conditions. The analysis result is of great significance to enhance the quality and reliability of the chassis.

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