Stability and Vibration of Imperfect Column and Slender Web

2014 ◽  
Vol 969 ◽  
pp. 328-331
Author(s):  
Ľuboš Šnirc ◽  
Jan Ravinger
Keyword(s):  
Residual Stresses ◽  
Linear Theory ◽  
Stiffness Matrix ◽  
Natural Vibration ◽  
Thin Walled Structures ◽  
Geometrical Imperfections ◽  
Thin Walled ◽  
Non Destructive ◽  
Structural Imperfections ◽  
Lagrange Description

Using the geometric non-linear theory (The Total Lagrange Description) in dynamics we can establish the problem of the natural vibration of the structure including the effects of the structural and geometrical imperfections. The incremental stiffness matrix can take into account the residual stresses (structural imperfections) and the geometrical initial displacements (geometrical imperfections) as well. The behaviour of columns, frames and thin-walled structures is sensitive to imperfections. This theory and results can be used as a base for the non-destructive method for the evaluation of the level of the load and the imperfections.

scholarly journals A Simplified Method to Simulate Residual Stresses in Plates

2020 ◽  
Author(s):  
José Manuel Gordo ◽  
Gonçalo Teixeira
Keyword(s):  
Residual Stresses ◽  
Thermal Process ◽  
Structural Strength ◽  
Finite Element Models ◽  
Welded Structures ◽  
Thin Walled Structures ◽  
Simplified Method ◽  
Geometrical Imperfections ◽  
Adequate Representation ◽  
Thin Walled

Welded structures are subjected to internal residual stress after manufacturing that may affect the structural strength and normally are associated with an increase on initial geometrical imperfections. This study presents a simplified method to generate an adequate representation of residual stresses on Finite Element models for structural analysis of thin-walled structures and other applications. The results obtained shown that the methodology proposed to introduce residual stresses is simple, accurate and efficient on the modulation of post-welding stresses and their pattern, thus it may be used for simulation of the thermal process.

Investigation of Residual Stresses in Thin-Walled Structure and Slender Web

2015 ◽  
Vol 769 ◽  
pp. 153-158
Author(s):  
Lubos Snirc ◽  
Jan Ravinger
Keyword(s):  
Residual Stresses ◽  
Natural Frequency ◽  
Crucial Role ◽  
Ultimate Load ◽  
Plate Structures ◽  
Thin Walled Structures ◽  
Stiffness Properties ◽  
Thin Walled ◽  
Definition Of ◽  
Non Destructive

Presented paper offers simplified equations for evaluation of residual stresses. Residual stresses are very important for evaluation of properties of steel thin-walled structures. They play a crucial role in definition of ultimate load and stiffness properties. Generally the residual stresses must be in equilibrium. In the case of statically determinate beam structures residual stresses do not have influence for natural frequency. But in case of plate structures situation is different. Relationship between residual stresses and natural frequency can be used as the base for preparation of non-destructive method for the investigation of residual stresses in thin-walled structures.

scholarly journals Non-destructive test of thin-walled structures by using holographic interferometry and 3D-optic system

2002 ◽  
Vol 5 ◽  
pp. 847-854
Author(s):  
Hiroshi Matsuda ◽  
Yusuke Oishi ◽  
Takanari Kanbara ◽  
Masahiko Nakamura ◽  
Takeshi Sakiyama
Keyword(s):  
Holographic Interferometry ◽  
Optic System ◽  
Destructive Test ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Non Destructive

A comparative study of two experimental techniques for the measurement of residual stresses in circular rods and tubes of perspex

1989 ◽  
Vol 24 (3) ◽  
pp. 163-171
Author(s):  
R K Mittal ◽  
I A Khan
Keyword(s):  
Residual Stresses ◽  
Cross Section ◽  
The Other ◽  
Experimental Techniques ◽  
Entire Cross Section ◽  
Sum Rule ◽  
Thin Walled ◽  
Removal Technique ◽  
Non Destructive ◽  
Distribution Of Stresses

Two experimental techniques have been used to measure residual stresses in circular rods and tubes of perspex, i.e., polymethyl methacrylate (PMMA). The first technique, based on photoelasticity, is non-destructive and easy to apply. It gives distribution of stresses over the entire cross-section. The analysis of this technique has been improved to relax some restrictions. The other technique is the layer removal technique. A serious drawback of this technique is that it fails to give the distribution of stresses over the entire cross-section and its accuracy for thin walled tubes is doubtful. A simplification of this technique is possible if the kinematic assumption introduced by Nishimura is replaced by one using the sum rule of stresses.

Process Maps for Predicting Residual Stress and Melt Pool Size in the Laser-Based Fabrication of Thin-Walled Structures

2006 ◽  
Vol 129 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Aditad Vasinonta ◽  
Jack L. Beuth ◽  
Michelle Griffith
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Pool Size ◽  
Thermal Gradients ◽  
Manufacturing Strategy ◽  
Process Maps ◽  
Thin Walled Structures ◽  
Melt Pool ◽  
Thin Walled ◽  
Melt Pool Size

Thermomechanical models are presented for the building of thin-walled structures by laser-based solid freeform fabrication (SFF) processes. Thermal simulations are used to develop quasi-non-dimensional plots (termed process maps) that quantify the effects of changes in wall height, laser power, deposition speed, and part preheating on thermal gradients, with the goal of limiting residual stresses in manufactured components. Mechanical simulations are used to demonstrate the link between thermal gradients and maximum final residual stresses. The approach taken is analogous to that taken in previous research by the authors in developing process maps for melt pool length, for maintaining an optimal melt pool size during component fabrication. Process maps are tailored for application to the laser engineered net shaping process; however, the general approach, insights, and conclusions are applicable to most SFF processes involving a moving heat source, and to other laser-based fusion processes. Results from the residual stress simulations identify two mechanisms for reducing residual stresses and quantify maximum stress reductions achievable through manipulation of all process variables. Results from thermal gradient and melt pool length process maps are used to identify a manufacturing strategy for obtaining a consistent melt pool size while limiting residual stress in a thin-walled part.

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