Evaluation of the strain energy density control volume for a nanoscale singular stress field

2016 ◽  
Vol 39 (12) ◽  
pp. 1557-1564 ◽  
Author(s):  
P Gallo ◽  
T Sumigawa ◽  
T Kitamura ◽  
F Berto
Keyword(s):  
Energy Density ◽  
Stress Field ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Control Volume ◽  
Singular Stress ◽  
Density Control ◽  
Singular Stress Field

Fatigue Strength of Three Dimensional Welded Joints: A Synthesis Based on the Strain Energy Density over a Control Volume

2007 ◽  
Vol 348-349 ◽  
pp. 413-416
Author(s):  
M. Zappalorto ◽  
Filippo Berto ◽  
Paolo Lazzarin
Keyword(s):  
Experimental Data ◽  
Energy Density ◽  
Welded Joints ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Complex Geometry ◽  
Control Volume ◽  
Three Dimensional ◽  
Weld Toe ◽  
Weld Root

A recent approach based on the local strain energy density (SED) averaged over a given control volume is applied to well documented experimental data taken from the literature, all related to steel welded joints of complex geometry. This small size volume embraces the weld root or the weld toe, both regions modelled as sharp (zero notch radius) V-notches with different opening angles. The SED is evaluated from three-dimensional finite element models by using a circular sector with a radius equal to 0.28 mm. The data expressed in terms of the local energy fall in a scatter band recently reported in the literature, based on about 650 experimental data related to fillet welded joints made of structural steel with failures occurring at the weld toe or at the weld root.

High Temperature Fatigue Tests of a Cu-Be Alloy and Synthesis in Terms of Linear Elastic Strain Energy Density

2014 ◽  
Vol 627 ◽  
pp. 77-80 ◽  
Author(s):  
F. Berto ◽  
P. Gallo ◽  
P. Lazzarin
Keyword(s):  
High Temperature ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Control Volume ◽  
Elastic Strain Energy ◽  
Fatigue Tests ◽  
Tension Stress ◽  
High Temperature Fatigue ◽  
Fatigue Data

The present paper summarises the results from uniaxial-tension stress-controlled fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors’ knowledge, only a limited number of papers on these alloys under high-temperature fatigue are available in the literature and no results deal with notched components.The Cu-Be specimens fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarise in a single scatter-band all the fatigue data, independently of the specimen geometry.

A Bi-Material Wedge – a Model for the Prediction of Failure Initiation at Shape and Material Discontinuities

2006 ◽  
Vol 324-325 ◽  
pp. 1305-1308
Author(s):  
Jan Klusák ◽  
Zdeněk Knésl
Keyword(s):  
Energy Density ◽  
Crack Initiation ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Stress Concentrations ◽  
Singular Stress ◽  
Failure Initiation ◽  
Density Factor ◽  
Material Discontinuities ◽  
Energy Density Factor

Geometrical and material discontinuities in constructions lead to singular stress concentrations and consequently to a crack initiation. The model of a bi-material wedge makes it possible to analyse such construction points to assess their stability. The presented approach is based on the knowledge of the strain energy density factor distribution in the concentrator vicinity.

Assessment of Welded Joints by Strain Energy Density Approach Accounting for Misalignments and Geometrical Imperfections

2017 ◽  
Author(s):  
Marco Gaiotti ◽  
Cesare Mario Rizzo ◽  
Filippo Berto
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Control Volume ◽  
Element Analysis ◽  
Fatigue Assessment ◽  
Magnification Factors ◽  
Notch Stress ◽  
Geometrical Imperfections ◽  
Straightforward Computation

Among recently introduced fatigue assessment approaches, the ones based on the notch stress intensity factor (N-SIF) concept appear to be very promising, both because of their theoretically soundness and because of the possibility of straightforward computation of parameters believed to govern the fatigue process. Actually, while such approaches can be considered in between stress-based approaches and crack propagation ones, quantities like N-SIF and strain energy density in a control volume can be evaluated by finite element analysis according to nowadays well-established procedures, mostly already implemented in commercial FEM software. The present study moves from a former one, dealing with butt joints between typical shipbuilding shell plates, and aims at assessing how the misalignment influences the fatigue strength estimation when applying the strain energy density approach. Eventually, the capabilities of such approach in accounting for misalignments is demonstrated and results are found in agreement with magnification factors currently recommended by guidelines and rules when applying other, stress based, fatigue assessment approaches.

Optimization of Reinforcement for a Class of Openings in Plate Structures

1982 ◽  
Vol 49 (4) ◽  
pp. 916-920
Author(s):  
S. K. Dhir
Keyword(s):  
Energy Density ◽  
Stress Field ◽  
Elastic Plate ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Analytical Procedure ◽  
Optimum Amount ◽  
Plate Structures ◽  
Hole Shape ◽  
Strain Energy Density Function

A numerical/analytical procedure has been developed which yields the optimum amount of reinforcement for a given hole shape in a large elastic plate under prescribed boundary stresses. This procedure is based on determining the usual two complex potentials which describe the entire stress field, constructing the strain energy density function in terms of the unknown amount of reinforcement, integrating this function around the opening boundary, and finally minimizing this integral with respect to the reinforcement. The method is first developed for a general hole shape and then demonstrated in some detail for a circular and a square-like opening.

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