scholarly journals Direct method of load simulation in hull strength analysis of catamaran

2020 ◽  
Vol S-I (2) ◽  
pp. 230-236
Author(s):  
R. Chistyakov ◽  
◽  
P. Mudrik ◽  
Keyword(s):  
Direct Method ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Strength Analysis ◽  
Ship Motions ◽  
Regular Waves ◽  
Stress Strain ◽  
Internal Forces ◽  
External Forces ◽  
Force Calculation

This paper discusses three-dimensional formulation for the problem of external forces acting on catamaran hull, as well as performs stress-strain state analysis of the structures affected by the loads thus calculated. The purpose of this study was to develop a modern methodology for joint solution to the first and the second problem of naval structural mechanics based on panelpotential and finite-element models in three-dimensional formulation for the conditions of still water and regular waves. The study discusses various formulations of the problem and various methods of external force calculation. External load is estimated in two formulations: static (based on hydrostatic methods) and stationary dynamic (based on the linear theory of ship motions). Also, external forces and their respective stresses were estimated as per the procedure of the classification society. The case study of a catamaran illustrates the process of load calculation and stress-strain analysis, giving the results for various external forces, with their assessment and analysis of internal forces and displacements induced by them. The study yielded rather handy technique for stress-strain analysis of catamaran hull in 3D formulation, including spatial static trimming in still water and in waves of given profile, as well as calculation of displacement amplitudes in regular waves, calculation of phase pressure fields and accelerations on catamaran hull, with further export of calculated external loads to FE analysis software for stressstrain investigation of structurally similar model needed to understand how conservative this model is.

Stress-Strain-Analysis of Grapevine Pruning with Powered and Non-Powered Hand Tools

2000 ◽  
Vol 44 (22) ◽  
pp. 639-642 ◽  
Author(s):  
Jurij Wakula ◽  
Thomas Beckmann ◽  
Michael Hett ◽  
Kurt Landau
Keyword(s):  
Strain Analysis ◽  
Stress Factors ◽  
Climate Condition ◽  
Hand Tools ◽  
Stress Strain ◽  
Repetitive Movements ◽  
Power Tools ◽  
Power Hand Tools ◽  
External Forces

Non-power and power cutting hand tools are mainly used every day in vineyards for grapevines pruning during 5 months (November - March). The grapevines pruning with the help of non-power tools is very stressful for wine growers. Repetitive movements combined with external forces in finger-hand-wrist-system, extreme positions in arm-shoulder-system, climate condition are some of the stress factors. Grapevines pruning with 5 manual prunes produced by 3 different manufacture and 2 power hand tools (electrically and pneumatically) were analysed. The results reveal that grapevines pruning with pneumatic and electric prunes is up to 30% more effective (according to productivity) than cutting with non-powered hand tools. At the same time is grapevines cutting with power tools more stressful as with non-powered one.

scholarly journals Strain Analysis on Electrochemical Failures of Nanoscale Silicon Electrode Based on Three-Dimensional In Situ Measurement

2020 ◽  
Vol 10 (2) ◽  
pp. 468 ◽  
Author(s):  
Zhifeng Qi ◽  
Zhongqiang Shan ◽  
Weihao Ma ◽  
Linan Li ◽  
Shibin Wang ◽  
...  
Keyword(s):  
Silicon Film ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Image Correlation ◽  
Mechanical Parameters ◽  
Stress Strain ◽  
Full Field ◽  
Battery Capacity

Nanoscale silicon film electrodes in Li-ion battery undergo great deformations leading to electrochemical and mechanical failures during repeated charging-discharging cycles. In-situ experimental characterization of the stress/strain in those electrodes still faces big challenges due to remarkable complexity of stress/strain evolution while it is still hard to predict the association between the electrode cycle life and the measurable mechanical parameters. To quantificationally investigate the evolution of the mechanical parameters, we develop a new full field 3D measurement method combining digital image correlation with laser confocal profilometry and propose a strain criterion of the failure based on semi-quantitative analysis via mean strain gradient (MSG). The experimental protocol and results illustrate that the revolution of MSG correlates positively with battery capacity decay, which may inspire future studies in the field of film electrodes.

Netan — a computer program for the interactive analysis of geodetic networks

CISM journal ◽  
1989 ◽  
Vol 43 (1) ◽  
pp. 25-37 ◽  
Author(s):  
M.R. Craymer ◽  
P. Vaníček ◽  
A. Tarvydas
Keyword(s):  
Network Analysis ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Strength Analysis ◽  
Interactive Graphics ◽  
Analysis Program ◽  
Interactive Analysis ◽  
Graphical Displays ◽  
Different Types ◽  
Confidence Ellipses

A network analysis program package using interactive graphics has been developed. It has the capability of operating in one of three modes: variance-covariance analysis, geometrical strength analysis and strain analysis. Transfer from one mode to another is possible. The program produces graphical displays of various strength characteristics, strain parameters as well as the usual confidence ellipses and ellipsoids. Strain analysis is used to quantify network deformation in response to: changes in observation values and their weights, changes in position and position difference values and their weights, addition/deletion of observations and network densification. Geometrical strength of a network is portrayed by a series of plots showing the different attributes of strength. Both two- and three-dimensional networks using different types of observations can be accommodated. The expressions used to sequentialize the analyses are also described.

scholarly journals On assessment of dynamic strength in waves for detailed support-free models of hull structures

2019 ◽  
pp. 82-90
Author(s):  
Mikhail Mironov ◽  
Roman Mudrik
Keyword(s):  
Three Dimensional ◽  
Dynamic Strength ◽  
Strength Analysis ◽  
Fe Model ◽  
Load Monitoring ◽  
Software Modules ◽  
Develop Software ◽  
Automated Algorithms ◽  
Mathcad Software ◽  
External Forces

Cross-disciplinary CAE-based calculations of ship movement and strains in fluid, at launching device, during ice interaction or in case of a navigation accident require very performant computers, and their results can neither differentiate specific movement shapes nor be checked by means of a physical experiment, so their verification is a very important task. Automated algorithms based on common assessment procedures for movement components and external forces made it possible to not only verify numerical calculations of apparent dynamics, but also to obtain justified and rational layouts for arrangement of external load monitoring sensors, as well as to refine these common procedures as a separate field of studies and use more accurate estimates of external forces in design algorithms. The task is to correctly transfer the obtained information on movement and pressure fields to the analytical model under straining. The model is support-free, so kinematic conditions must be imposed on it so as not to distort realistic stressed state. In the unsteady formulation, it is necessary to correctly consider inertial and damping properties of fluid and structure itself, ensuring correct transition to the quasi-static formulation. Computer-based algebra of PTC MathCAD software made it possible for the authors to develop software modules for three-dimensional motion calculations of ships with arbitrary hull shape and loading, as well as APDL ANSYS applications for applying the data on external loads in stress-strain state calculations of support-free FE model of ship in frequency and time domain. The authors managed to develop a viable open-source solution for a cross-software system meant for dynamic strength analysis of ships in waves, which can be upgraded by non-programmers.

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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