Effective elastic moduli of metal honeycombs manufactured using selective laser melting

2020 ◽  
Vol 26 (5) ◽  
pp. 971-980 ◽  
Author(s):  
Rafid Hussein ◽  
Sudharshan Anandan ◽  
Myranda Spratt ◽  
Joseph W. Newkirk ◽  
K. Chandrashekhara ◽  
...  
Keyword(s):  
Strain Energy ◽  
Elastic Moduli ◽  
Three Dimensional ◽  
Analytical Models ◽  
Effective Elastic Moduli ◽  
Effective Moduli ◽  
Content Type ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Purpose Honeycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic performance. This paper aims to use numerical modeling to investigate the effective elastic moduli, in-plane and out-of-plane, for thick-walled honeycombs manufactured using selective laser melting (SLM). Design/methodology/approach Theoretical predictions were performed using homogenization on a sample scale domain equivalent to the as-manufactured dimensions. A Renishaw AM 250 machine was used to manufacture hexagonal honeycomb samples with wall thicknesses of 0.2 to 0.5 mm and a cell size of 3.97 mm using 304 L steel powder. The SLM-manufactured honeycombs and cylindrical test coupons were tested using flatwise and edgewise compression. Three-dimensional finite element and strain energy homogenization were conducted to determine the effective elastic properties, which were validated by the current experimental outcomes and compared to analytical models from the literature. Findings Good agreement was found between the results of the effective Young’s moduli ratios numerical modeling and experimental observations. In-plane effective elastic moduli were found to be more sensitive to geometrical irregularity compared to out-of-plane effective moduli, which was confirmed by the analytical models. Also, it was concluded that thick-walled SLM manufactured honeycombs have bending-dominated in-plane compressive behavior and a stretch-dominated out-of-plane compressive behavior, which matched well with the simulation and numerical models predictions. Originality/value This work uses three-dimensional finite element and strain energy homogenization to evaluate the effective moduli of SLM manufactured honeycombs.

Prediction of the yielding behaviour of ductile porous materials through computational homogenization

2018 ◽  
Vol 35 (2) ◽  
pp. 604-621
Author(s):  
Rodrigo Pinto Carvalho ◽  
Igor A. Rodrigues Lopes ◽  
Francisco M. Andrade Pires
Keyword(s):  
Three Dimensional ◽  
Yield Locus ◽  
Analytical Models ◽  
Finite Element Models ◽  
Content Type ◽  
Ductile Materials ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Void Geometry ◽  
The Impact

Purpose The purpose of this paper is to predict the yield locus of porous ductile materials, evaluate the impact of void geometry and compare the computational results with existing analytical models. Design/methodology/approach A computational homogenization strategy for the definition of the elasto-plastic transition is proposed. Representative volume elements (RVEs) containing single-centred ellipsoidal voids are analysed using three-dimensional finite element models under the geometrically non-linear hypothesis of finite strains. Yield curves are obtained by means of systematic analysis of RVEs considering different kinematical models: linear boundary displacements (upper bound), boundary displacement fluctuation periodicity and uniform boundary traction (lower bound). Findings The influence of void geometry is captured and the reduction in the material strength is observed. Analytical models usually overestimate the impact of void geometry on the yield locus. Originality/value This paper proposes an alternative criterion for porous ductile materials and assesses the accuracy of analytical models through the simulation of three-dimensional finite element models under geometrically non-linear hypothesis.

Influence of Interference and Clamping on Fretting Fatigue in Single Rivet-Row Lap Joints

2000 ◽  
Vol 123 (4) ◽  
pp. 686-698 ◽  
Author(s):  
K. Iyer ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Crack Initiation ◽  
Three Dimensional ◽  
Fretting Fatigue ◽  
Cyclic Stress ◽  
Lap Joints ◽  
Element Analysis ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Fretting Damage

Primary fretting fatigue variables such as contact pressure, slip amplitude and bulk cyclic stresses, at and near the contact interface between the rivet shank and panel hole in a single rivet-row, 7075-T6 aluminum alloy lap joint are presented. Three-dimensional finite element analysis is applied to evaluate these and the effects of interference and clamping stresses on the values of the primary variables and other overall measures of fretting damage. Two rivet geometries, non-countersunk and countersunk, are considered. Comparison with previous evaluations of the fretting conditions in similar but two-dimensional connections indicates that out-of-plane movements and attending effects can have a significant impact on the fatigue life of riveted connections. Variations of the cyclic stress range and other proponents of crack initiation are found to peak at distinct locations along the hole-shank interface, making it possible to predict crack initiation locations and design for extended life.

Examination of Response of a Skewed Steel Bridge Superstructure During Deck Placement

2003 ◽  
Vol 1845 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Elizabeth K. Norton ◽  
Daniel G. Linzell ◽  
Jeffrey A. Laman
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Analytical Models ◽  
Levels Of Analysis ◽  
Steel Bridge ◽  
Bridge Superstructure ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Skewed Bridge

The response of a 74.45-m (244-ft 0-in.) skewed bridge to the placement of the concrete deck was monitored to compare measured and predicted behavior. This comparison was completed to ( a) determine theoretical deflections and rotations with analytical models for comparison to actual deformations monitored during construction; ( b) compare the results of various levels of analysis to determine the adequacy of the methods; and ( c) examine variations on the concrete placement sequence to determine the most efficient deck placement methods. Two levels of analysis were used to achieve the objectives. Level 1 was a two-dimensional finite element grillage model analyzed with STAAD/Pro. Level 2 was a three-dimensional finite element model analyzed with SAP2000. These studies are discussed and findings are presented.

Three-Dimensional Analyses of Single Rivet-Row Lap Joints — Part I: Elastic Response

1999 ◽  
Author(s):  
K. Iyer ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Stress Concentration ◽  
Load Transfer ◽  
Three Dimensional ◽  
Lap Joints ◽  
Elastic Response ◽  
Lap Joint ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Contact Pressures

Abstract Three-dimensional finite element analyses (FEA) of an elastic, single rivet-row, aluminum alloy lap joint are presented. The effects of rivet geometry (countersinking), rivet material and interfacial friction coefficient are examined. Interference and lateral clamping are not treated. Panels loaded in tension with vacant, tapered holes are also examined. Load transfer through the joint, the joint compliance, rivet-tilt, the local slips at rivet-panel and panel-panel interfaces, contact pressures and local stresses are evaluated. Relations between these features and the contact and bending driven stress concentration are clarified. The work shows that the stress concentration factor, rivet-panel slips, peak stresses, contact pressures and rivet deformation are all related, and increase with the severity of the countersink. Panel bending, rivet tilt and countersinking introduce large, out-of-plane stress gradients and shift the peak stresses to the interior surface of the countersunk panel. The results demonstrate the importance of out-of-plane distortions in accounting for the behavior of the riveted lap joints. Three opportunities are identified for improving lap joint performance without increasing the weight.

Thermal-stress analysis and calculation of single and dual chip set double-sided circuit board based on three-dimensional finite element algorithm

Circuit World ◽  
2015 ◽  
Vol 41 (2) ◽  
pp. 49-54
Author(s):  
Lan Song ◽  
Yang Zhao ◽  
Yaoming Zhou ◽  
Haifei Xiang
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Thermal Stress ◽  
Three Dimensional ◽  
Circuit Board ◽  
Content Type ◽  
Thermal Stress Field ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Element Algorithm

Purpose – The purpose of this paper is to analyze and figure out the temperature field and thermal stress field with the calculation model of thermal insulation material and composite material. Design/methodology/approach – The paper adopted the three-dimensional finite element algorithm. Findings – The simulated results showed great shearing strength between the chipset and the printed circuit board. The position of chip exerts great influence on the distribution of temperature field and thermal stress field of circuit board. The reasonable distribution of chip will effectively reduce the temperature extremum and stress extremum of circuit board. Originality/value – The paper analyzes and presents a discussion of the problems relating to the density of electronic packaging. The analysis process and the method of the paper provide essential help in resolving electronic device heat problems.

A Three-Dimensional Finite Element Stress Analysis and Strength Prediction of CFRP Adhesive Laminated Plates Subjected to Static and Impact Out-of-Plane Loadings

2009 ◽  
Author(s):  
Yukiya Noshita ◽  
Toshiyuki Sawa ◽  
Yuya Omiya
Keyword(s):  
Equivalent Stress ◽  
Three Dimensional ◽  
Laminated Plates ◽  
Stress Distributions ◽  
Maximum Value ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Three Dimensional Finite Element

Stress distributions in CFRP adhesive laminated plates subjected to static and impact out-of-plane loadings are analyzed using a three-dimensional finite-element method (FEM). For establishing an optimum design method of the laminated plates, the effects of some factors are examined. As the results, it is found that the maximum value of the von Mises equivalent stress σ eqv occurs at the edge of the CFRP’s interfaces. The maximum value of interface shear stress r i at CFRP interface decreases as the reinforced Young’s modulus and the thickness increases. However, the maximum value of σ eqv at the adhesive layer decreases as the reinforced Young’s modulus and the thickness decreases. In addition, the maximum value of r i at the CFRP’s interface of lower reinforced laminates under impact loadings shows opposite characteristics to those under static loadings. For verification of the FEM calculations, experiments were carried out to measure the strains at the interfaces and the laminates plates strengths. Concerning strain and strength prediction based on von Mises equivalent stress, fairly good agreements were found between the numerical and the experimental results. The FEM results of impacted strain are in fairly good consistent with the measured results. Discussion is made on the effects of some factors on interface stress distributions.

Assessment of Analytical Predictions for Radial Growth of Rotating Labyrinth Seals

2018 ◽  
Vol 35 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Sivakumar Subramanian ◽  
A. S. Sekhar ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Rotational Speed ◽  
Radial Growth ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Analytical Models ◽  
Length Ratio ◽  
Labyrinth Seals ◽  
High Rotational Speed ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Abstract Radial growth predictions of rotating labyrinth seals are conventionally obtained from one-dimensional analytical models. However, these predictions quantitatively differ within themselves by about 5-500 %. Simulations using three-dimensional finite element method (FEM) are carried out in this paper for a typical labyrinth seal, subjected to high rotational speed and temperature, for a range of radius-to-length ratio of the rotor. Taking the predicted values by FEM as reference, four analytical models are assessed and their errors are quantified. These errors are found to be independent of rotational speed and temperature but significantly vary with the radius-to-length ratio of the rotor. Based on this finding, simple analytical models, together with correction factor charts, are suggested.

Induced voltage analysis of superconducting fault current limiter

2013 ◽  
Vol 33 (1/2) ◽  
pp. 38-46 ◽  
Author(s):  
Zhigao Wang ◽  
Shuhong Wang ◽  
Jie Qiu ◽  
Weizhi Gong ◽  
Jingyin Zhang
Keyword(s):  
Short Circuit ◽  
Three Dimensional ◽  
Electric Circuit ◽  
Short Circuit Current ◽  
Fault Current Limiter ◽  
Induced Voltage ◽  
Superconducting Fault Current Limiter ◽  
Content Type ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Purpose – Saturated core type superconducting fault current limiter (SFCL) can effectively limit the short-circuit current in power system. However, the high induced voltage will occur between the terminals of DC superconducting bias winding caused by the variation of magnetic flux linked by DC winding due to the increasing short-circuit current. The DC source may be damaged. Thus, the induced voltage should be considered in DC winding design. The paper aims to discuss these issues. Design/methodology/approach – Three-dimensional finite element method coupled with electric circuit. Findings – The short-circuit current flowing through AC windings and induced voltage of DC winding are analyzed by using three-dimensional finite element method coupled with electric circuit for a 220-kV three-phase SFCL. Several circuit elements, such as a capacitor connected with DC winding in parallel, an additional short-circuit winding wound around DC core column and an energy-released piezoresistor, are, respectively, used for induced voltage reduction. These methods aim to save magnetic coupled energy in DC winding, or oppose the variation of magnetic flux, or limit the voltage of DC winding by using a resistor with low resistance. Originality/value – The different methods for reduction of induced voltage of superconducting DC winding are studied and discussed. The decreased induced voltage may benefit the safety of superconducting DC winding and the source.

A Three-Dimensional Finite Element Stress Analysis of Plain-Woven CFRP Adhesive Laminated Plates and Hollow Cylinder Under Out-of-Plane Loading

2008 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yukiya Noshita ◽  
Takeshi Iwamoto
Keyword(s):  
Finite Element ◽  
Hollow Cylinder ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Laminated Plates ◽  
Stress Distributions ◽  
Specific Strength ◽  
Out Of Plane ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Carbon-Fiber-Reinforced-Plastic (CFRP) laminates have been used extensively in many industrial applications because of their good mechanical properties, such as high specific strength and elastic modulus. However, when CFRP laminated plate is bent, cracks and delaminations occur at the interfaces where fiber orientations are changed. Therefore, it is important to know the stress distributions at the interfaces. In this study, the stress distributions of plain-woven CFRP adhesive laminated plates and hollow cylinder bonded reinforcements under out-of-plane loads are examined. Stress distributions in the CFRP laminated plates are analyzed using three-dimensional Finite Element Method. The effects of the thickness, stiffness and length of coating reinforcements are examined in the numerical calculations. The three point bending tests were carried out for the verifications of the FEM calculations. The strains at the interfaces, the deflection and the delaminations stress were measured under static out-of-plane loading. A fairly good agreement was seen between the FEM calculations and the experimental results concerning the strains and the deflections. Moreover, the mechanism of delaminations is examined using the interface stress distributions in the CFRP laminated plates.

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