scholarly journals INFLUENCE OF MATERIAL CHARACTERISTICS STRESS-STRAIN ON THE RESULTS OF FEM JOINT CONNECTION OF COLD-FORMED SECTIONS

2021 ◽  
Vol 177 (27) ◽  
pp. 101-105
Author(s):  
Mariusz Kosiń ◽  
Keyword(s):  
Stress Strain ◽  
Material Characteristics ◽  
Joint Connection

Analysis of Bolted Joints with Nonlinear Gasket Behavior

1980 ◽  
Vol 102 (3) ◽  
pp. 249-256 ◽  
Author(s):  
A. I. Soler
Keyword(s):  
Structural Integrity ◽  
Linear Models ◽  
Bolted Joint ◽  
Stress Strain ◽  
Highly Nonlinear ◽  
Nonlinear Stress ◽  
Joint Connection ◽  
Leak Tightness ◽  
Gasket Material ◽  
Full Face

Design methods for full face gaskets in bolted pressure vessel joints have received little attention in the literature. Such gasketed joints play a prominent role in attaching rectangular plan from water boxes to rectangular tubesheets in condenser water boxes. With higher cooling water pressures becoming evident due to cooling tower circuits, the water box-tubesheet structure, and its bolted joint connection requires rigorous analysis for both structural integrity and leak tightness. Although it is well known that gasket material has a highly nonlinear stress strain behavior, very few analyses are available to calculate and evaluate the effect of the nonlinear gasket behavior in a bolted joint connection. In this paper, an approximate method for simultaneously analyzing structural integrity and leak tightness of typical bolted flange connections with nonlinear gasket material is developed. The flange is modeled as an elastic element, the bolt is simulated by a linear spring with bending and extensional resistance, and the gasket is modeled by a series of nonlinear compression springs. A simple nonlinear stress-strain relation for initial loading and unloading of the gasket is developed based on experimental data. The analysis technique employs an incremental procedure which follows the configuration through preloading and pressurization and checks structural integrity and gasket leakage. To illustrate the method, a typical full face gasket and flange construction is studied, and the effect of gasket properties on the final state is investigated. A series of simulation results are obtained which illustrate clearly the effect of gasket prestrain, undersizing of bolts, and wall rotational resistance. Of particular importance is a simulation comparing results obtained using actual nonlinear gasket stress-strain data with results obtained using linear models for the gasket. It is demonstrated that for full face gasket configurations, simulation of the nonlinear behavior is required to achieve accurate results. The procedure developed in this work is ideal for optimization of flange gasket configurations because of its cost effectiveness while simultaneously evaluating the interaction between structural integrity and joint leak tightness.

Effect of deformation rate on the stress-strain curves of gelatin gels

1996 ◽  
Vol 93 ◽  
pp. 837-849 ◽  
Author(s):  
A Bot ◽  
IA van Amerongen ◽  
RD Groot ◽  
NL Hoekstra ◽  
WGM Agterof
Keyword(s):  
Deformation Rate ◽  
Stress Strain ◽  
Gelatin Gels

КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ХВОСТО-ВИХ БАЛОК СІТЧАСТОГО ТИПУ З ПОЛІМЕРНИХ КОМПО-ЗИЦІЙНИХ МАТЕРІАЛІВ ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ

2020 ◽  
pp. 15-30
Author(s):  
А. Г. Гребеников ◽  
И. В. Малков ◽  
В. А. Урбанович ◽  
Н. И. Москаленко ◽  
Д. С. Колодийчик
Keyword(s):  
Finite Element ◽  
Strain State ◽  
Layer Structure ◽  
Metal Structure ◽  
Element Model ◽  
Stress Strain ◽  
Element Analysis ◽  
Mesh Structure ◽  
Stress Strain State ◽  
Mesh Structures

The analysis of the design and technological features of the tail boom (ТB) of a helicopter made of polymer composite materials (PCM) is carried out.Three structural and technological concepts are distinguished - semi-monocoque (reinforced metal structure), monocoque (three-layer structure) and mesh-type structure. The high weight and economic efficiency of mesh structures is shown, which allows them to be used in aerospace engineering. The physicomechanical characteristics of the network structures are estimated and their uniqueness is shown. The use of mesh structures can reduce the weight of the product by a factor of two or more.The stress-strain state (SSS) of the proposed tail boom design is determined. The analysis of methods for calculating the characteristics of the total SSS of conical mesh shells is carried out. The design of the tail boom is presented, the design diagram of the tail boom of the transport category rotorcraft is developed. A finite element model was created using the Siemens NX 7.5 system. The calculation of the stress-strain state (SSS) of the HC of the helicopter was carried out on the basis of the developed structural scheme using the Advanced Simulation module of the Siemens NX 7.5 system. The main zones of probable fatigue failure of tail booms are determined. Finite Element Analysis (FEA) provides a theoretical basis for design decisions.Shown is the effect of the type of technological process selected for the production of the tail boom on the strength of the HB structure. The stability of the characteristics of the PCM tail boom largely depends on the extent to which its design is suitable for the use of mechanized and automated production processes.A method for the manufacture of a helicopter tail boom from PCM by the automated winding method is proposed. A variant of computer modeling of the tail boom of a mesh structure made of PCM is shown.The automated winding technology can be recommended for implementation in the design of the composite tail boom of the Mi-2 and Mi-8 helicopters.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

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