scholarly journals Design of a Microfabricated Device for the Ligase Detection Reaction (LDR)

2004 ◽  
Author(s):  
Dwhyte O. Barrett ◽  
Amit Maha ◽  
Yun Wang ◽  
Steven A. Soper ◽  
Dimitris E. Nikitopoulos ◽  
...  
Keyword(s):  
Deoxyribonucleic Acid ◽  
Fluorescent Dyes ◽  
Point Mutations ◽  
Thermoelectric Module ◽  
Cooling Zone ◽  
Test Device ◽  
Element Analysis ◽  
Ligase Detection Reaction ◽  
Identification Process ◽  
Aspect Ratios

The Ligase Detection Reaction (LDR) is a mutation detection technique used to identify point mutations in deoxyribonucleic acid (DNA). A microscale Ligase Detection Reaction (LDR) device was designed and manufactured in polycarbonate. There are at least two mixing stages involved in the LDR identification process. Various micromixers were simulated in Fluent (v5.4, Lebanon, NH) and several test geometries were selected for fabrication. Passive diffusional micromixers were made with aspect ratios from 7 to 20. The mixers were made by SU-8 lithography, LIGA, laser ablation and micromilling to characterize each fabrication method. It was found that LIGA was best for making the micromixers, but was the longest process. The micromixers were fabricated and are being tested using fluorescent dyes. For a successful reaction temperatures of 0°C, 95°C and 65°C were needed. A stationary chamber method was used with thermal cycling in which the sample held while the temperature is cycled. Finite element analysis showed uniform temperatures in the rectangular 1.5 μl chambers and that air slits can effectively separate the thermal cycle zone from the 0°C cooling zone and the mixing region. A test device was laid out and micromilled with the temperature zones. A commercial thin film heater and a thermoelectric module were used with a PID controller to obtain the required process temperatures. Heating from 65°C to 95°C took 10 seconds, while cooling from 95°C to 65°C also took 10 seconds. The residence times at the required temperatures can adapt to changes in the LDR as parameters and reactant concentrations are varied.

scholarly journals Influence of the patch loading length on the buckling coefficient of longitudinally stiffened plate girders

2019 ◽  
Author(s):  
Nelson Loaiza ◽  
Carlos Graciano ◽  
Rolando Chacón
Keyword(s):  
Elastic Buckling ◽  
Stiffened Plate ◽  
Element Analysis ◽  
Geometrical Properties ◽  
Plate Girders ◽  
Linear Finite Element ◽  
Aspect Ratios ◽  
Buckling Behavior ◽  
Buckling Coefficient ◽  
Patch Loading

This paper aims at investigating the effect of the bearing length on the elastic buckling behavior of longitudinally stiffened girder webs subjected to patch loading. Buckling coefficients are calculated by means of linear finite element analysis. Furthermore, a parametric analysis is performed to study the influence of other geometric parameters such as the panel aspect ratio and the geometrical properties of the longitudinal ones. Buckling coefficients of longitudinally stiffened girder webs are computed numerically. The results show that the buckling coefficient for longitudinally stiffener girder webs increases with the loading length. However, this conclusion is considerably affected by other factors such as the position of the stiffener, and panel aspect ratios.

VIBRATION AND DYNAMIC INSTABILITY OF STIFFENED PLATES SUBJECTED TO IN-PLANE HARMONIC EDGE LOADING

2002 ◽  
Vol 02 (02) ◽  
pp. 185-206 ◽  
Author(s):  
A. K. L. SRIVASTAVA ◽  
P. K. DATTA ◽  
A. H. SHEIKH
Keyword(s):  
Dynamic Instability ◽  
Stiffened Plates ◽  
Stiffened Plate ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Stiffness Properties ◽  
Edge Loading ◽  
Instability Regions ◽  
Varying Mass ◽  
Good Agreement

The vibration and dynamic instability behavior of a stiffened plate subjected to uniform in-plane edge loading is studied using finite element analysis. The method of Hill's infinite determinants is applied to analyze the dynamic instability regions. Rectangular stiffened plates possessing different boundary conditions, aspect ratios, varying mass and stiffness properties and varying number of stiffeners have been analyzed for dynamic instability. The results are obtained considering the bending displacements of the plate and the stiffener. Eccentricity of the stiffeners give rise to axial and bending displacement in the middle plane of the plate. The results show that the principal instability regions have a significant effect considering and neglecting in-plane displacements. Comparison with published results indicates good agreement.

Application of ASME Code Section XI Appendix L Using 3-D Finite Element Analyses

2020 ◽  
Author(s):  
Charles Fourcade ◽  
Minji Fong ◽  
James Axline ◽  
Do Jun Shim ◽  
Chris Lohse ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Growth ◽  
Cyclic Stress ◽  
Finite Element Analyses ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Flaw Tolerance ◽  
Asme Code ◽  
Stress Ratios

Abstract As part of a fatigue management program for subsequent license renewal, a flaw tolerance evaluation based on ASME Code, Section XI, Appendix L may be performed. The current ASME Code, Section XI, Appendix L flaw tolerance methodology requires determination of the flaw aspect ratio for initial flaw size calculation. The flaw aspect ratios listed in ASME Section XI, Appendix L, Table L-3210-2, for austenitic piping for example, are listed as a function of the membrane-to-gradient cyclic stress ratio. The Code does not explicitly describe how to determine the ratio, especially when utilizing complex finite element analyses (FEA), involving different loading conditions (i.e. thermal transients, piping loads, pressure, etc.). The intent of the paper is to describe the methods being employed to determine the membrane-to-gradient cyclic stress ratios, and the corresponding flaw aspect ratios (a/l) listed in Table L-3210-2, when using finite element analysis methodology. Included will be a sample Appendix L evaluation, using finite element analysis of a pressurized water reactor (PWR) pressurizer surge line, including crack growth calculations for circumferential flaws in stainless steel piping. Based on this example, it has been demonstrated that, unless correctly separated, the membrane-to-gradient cyclic stress ratios can result in extremely long initial flaw lengths, and correspondingly short crack growth durations.

scholarly journals Geometrical behavior of laminated graphite/epoxy composite using hypermesh

2018 ◽  
Vol 7 (2.20) ◽  
pp. 214
Author(s):  
Ch Siva RamaKrishna ◽  
KV Subba Rao ◽  
Saineelkamal Arji
Keyword(s):  
Residual Stresses ◽  
Epoxy Composite ◽  
Weight Ratio ◽  
Laminated Composite ◽  
High Strength ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Military Applications ◽  
Inherent Strength

The laminated composite material is  made of ply which are specically used in automotive, aerospace and military applications due to less in weight and high strength to weight ratio. The role of structural strength is very important in composites, as the material is weak in inherent strength leads to damage of equipment made with the laminated composite. Hence, an accurate understanding of their structural geometrical behavior for residual stresses is required, such as residual stresses with different aspect ratios. In present work, various aspect ratios of laminated composite and its residual stresses are investigated using finite element analysis. The numerical results showed, on the residual stresses, that the effects the change the residual stresses due change of aspect ratio of laminated Graphite/epoxy composite. 

The interfacial reliability of through-glass vias for 2.5D integrated circuits

2020 ◽  
Vol 37 (4) ◽  
pp. 181-188
Author(s):  
Omar Ahmed ◽  
Golareh Jalilvand ◽  
Scott Pollard ◽  
Chukwudi Okoro ◽  
Tengfei Jiang
Keyword(s):  
Integrated Circuits ◽  
Material Selection ◽  
Thermal Mismatch ◽  
Element Analysis ◽  
Content Type ◽  
Interfacial Delamination ◽  
Mismatch Strain ◽  
Aspect Ratios ◽  
Interfacial Reliability ◽  
The Impact

Purpose Glass is a promising interposer substrate for 2.5 D integration; yet detailed analysis of the interfacial reliability of through-glass vias (TGVs) has been lacking. The purpose of this paper is to investigate the design and material factors responsible for the interfacial delamination in TGVs and identify methods to improve reliability. Design/methodology/approach The interfacial reliability of TGVs is studied both analytically and numerically. An analytical solution is presented to show the dependence of the energy release rate (ERR) for interfacial delamination on the via design and the thermal mismatch strain. Then, finite element analysis (FEA) is used to investigate the influence of detailed design and material factors, including the pitch distance, via aspect ratio, via geometry and the glass and via materials, on the susceptibility to interfacial delamination. Findings ERR for interfacial delamination is directly proportional to the via diameter and the thermal mismatch strain. Thinner wafers with smaller aspect ratios show larger ERRs. Changing the via geometry from a fully filled via to an annular via leads to lower ERR. FEA results also show that certain material combinations have lower thermal mismatch strains, thus less prone to delamination. Practical implications The results and approach presented in this paper can guide the design and development of more reliable 2.5 D glass interposers. Originality/value This paper represents the first attempt to comprehensively evaluate the impact of design and material selection on the interfacial reliability of TGVs.

scholarly journals Active Microstructured Optical Arrays of Grazing Incidence Reflectors

2010 ◽  
Vol 2010 ◽  
pp. 1-15
Author(s):  
Richard Willingale ◽  
Charlotte Feldman ◽  
Alan Michette ◽  
Tim Button ◽  
Camelia Dunare ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Optical Design ◽  
Grazing Incidence ◽  
X Rays ◽  
Element Analysis ◽  
Tissue Samples ◽  
Aligned Arrays ◽  
Aspect Ratios ◽  
Radiation Induced ◽  
The Uk

The UK Smart X-Ray Optics (SXO) programme is developing active/adaptive optics for terrestrial applications. One of the technologies proposed is microstructured optical arrays (MOAs), which focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels. Although such arrays are similar in concept to polycapillary and microchannel plate optics, they can be bent and adjusted using piezoelectric actuators providing control over the focusing and inherent aberrations. Custom configurations can be designed, using ray tracing and finite element analysis, for applications from sub-keV to several-keV X-rays, and the channels of appropriate aspect ratios can be made using deep silicon etching. An exemplar application will be in the microprobing of biological cells and tissue samples using Ti Kα radiation (4.5 keV) in studies related to radiation-induced cancers. This paper discusses the optical design, modelling, and manufacture of such optics.

An Improved Method for Designing Flexure-Based Nonlinear Springs

2012 ◽  
Author(s):  
Qiaoling Meng ◽  
Giovanni Berselli ◽  
Rocco Vertechy ◽  
Vincenzo Parenti Castelli
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanisms ◽  
Empirical Equations ◽  
Element Analysis ◽  
Closed Form Solutions ◽  
Nonlinear Springs ◽  
Aspect Ratios ◽  
Analytical Relations ◽  
Flexural Hinges

Monolithic Flexure-based Compliant Mechanisms (MFCM) can functionally act as nonlinear springs by providing a desired load-displacement profile at one point on their structure. Once the MFCM topology is chosen, these particular springs can be conveniently synthesized by resorting to the well-known Pseudo-Rigid-Body approximation, whose accuracy strongly depends on the modeling precision of the flexures’ principal compliance. For various types of flexures, closed-form solutions have been proposed which express the compliance factors as functions of the flexure dimensions. Nonetheless, the reliability of these analytical relations is limited to slender, beam-like, hinges undergoing small deflections. In order to overcome such limitations, this paper provides empirical equations, derived from finite element analysis, that can be used for the optimal design of circular, elliptical, and corner-filleted flexural hinges with general aspect ratios on the basis of both principal compliance and maximum bearable stress. As a case study, a nonlinear spring conceived as a four-bar linkage MFCM is synthesized and simulated by means of finite element analysis. Numerical results confirm that the aforementioned empirical equations outperform their analytical counterparts when modeling thick cross-section hinges undergoing large deflections.

A boundary-element analysis of flagellar propulsion

1987 ◽  
Vol 184 ◽  
pp. 533-549 ◽  
Author(s):  
N. Phan-Thien ◽  
T. Tran-Cong ◽  
M. Ramia
Keyword(s):  
Boundary Element ◽  
Cell Body ◽  
Quantitative Agreement ◽  
Optimum Number ◽  
Element Analysis ◽  
Slender Body Theory ◽  
Aspect Ratios ◽  
Optimal Value ◽  
Micro Organisms ◽  
Body Theory

The swimming of a flagellar micro-organism by the propagation of helical waves along its flagellum is analysed by a boundary-element method. The method is not restricted to any particular geometry of the organism nor does it assume a specific wave motion for the flagellum. However, only results for an organism with a spherical or ellipsoidal cell body and a helically beating flagellum are presented here.With regard to the flagellum, it is concluded that the optimum helical wave (amplitude α and wavenumber k) has αk ≈ 1 (pitch angle of 45°) and that for the optimum flagellar length L/A = 10 (L being the flagellar length, A being the radius of the assumed spherical cell body) the optimum number of wavelengths Nλ is about 1.5. Furthermore there appears to be no optimal value for the flagellar radius a, with the thinner flagella being favoured. These conclusions show excellent quantitative agreement with those of slender-body theory.For the case of an ellipsoidal cell body, the optimum aspect ratios B/A and C/A of the ellipsoid are about 0.7 and 0.3 respectively; A, B and C are the principal radii of the ellipsoid. These and all of the above conclusions show good qualitative agreement with experimental observations of efficiently swimming micro-organisms.

Mechanical Characterization of Thin SOFC Electrolytes With Honeycomb Support

2013 ◽  
Vol 10 (1) ◽  
Author(s):  
Ryan B. Berke ◽  
Mark E. Walter
Keyword(s):  
Effective Properties ◽  
Mesoscale Model ◽  
Honeycomb Structure ◽  
Small Scale ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Electrolyte Membranes ◽  
Point Bend ◽  
Representative Area

Planar solid oxide fuel cells are made up of repeating sequences of electrolytes, electrodes, seals, and current collectors. The electrolyte should be as thin as possible for optimal electrochemical efficiency; however, for electrolyte-supported cells, the thin electrolytes are susceptible to damage during production, assembly, and operation. To produce cells that are sufficiently mechanically robust, electrolytes can be made having a cosintered honeycomb structure that supports thin, electrochemically efficient electrolyte membranes. Use of finite element analysis is desirable to mechanically characterize such electrolytes. To maintain reasonable numbers of elements and element aspect ratios, it is not possible to simultaneously model the small-scale details together with the overall membrane response. A two-scale approach is devised: the smaller mesoscale analyzes a representative area of the electrolyte, while the larger macroscale examines the electrolyte as a whole. Elastic properties for the mesoscale model are measured over a range of temperatures using a sonic resonance technique. Effective properties for the macroscale are obtained over a range of mesoscale geometries and can be obtained without needing to rerun the mesoscale simulations. The effective properties are experimentally validated using four-point bend experiments on representative samples. The bulk properties and the effective properties can then be used as material inputs for the macroscale model in order to design cells that are more sufficiently mechanically robust without sacrificing electrochemical performance.

Understanding Magnetic Flux Leakage Signals From Dents

2006 ◽  
Author(s):  
Lynann Clapham ◽  
Vijay Babbar ◽  
Alex Rubinshteyn
Keyword(s):  
Magnetic Flux ◽  
Pipe Wall ◽  
Experimental Studies ◽  
Mechanical Damage ◽  
Magnetic Behaviour ◽  
Magnetic Flux Leakage ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Stress Relieving ◽  
Flux Leakage

The Magnetic Flux Leakage (MFL) technique is sensitive both to pipe wall geometry and pipe wall stresses, therefore MFL inspection tools have the potential to locate and characterize mechanical damage in pipelines. However, the combined influence of stress and geometry make MFL signal interpretation difficult for a number of reasons: 1) the MFL signal from mechanical damage is a superposition of geometrical and stress effects, 2) the stress distribution around a mechanically damaged region is very complex, consisting of plastic deformation and residual (elastic) stresses, 3) the effect of stress on magnetic behaviour is not well understood. Accurate magnetic models that can incorporate both stress and geometry effects are essential in order to understand MFL signals from dents. This paper reports on work where FEA magnetic modeling is combined with experimental studies to better understand dents from MFL signals. In experimental studies, mechanical damage was simulated using a tool and die press to produce dents of varying aspect ratios (1:1, 2:1, 4:1), orientations (axial, circumferential) and depths (3–8 mm) in plate samples. MFL measurements were made before and after selective stress-relieving heat treatments. These annealing treatments enabled the stress and geometry components of the MFL signal to be separated. Geometry and stress ‘peaks’ tend in most cases to overlap — however stress features are most prominent in the dent rim region and geometry peaks over central region. In general the geometry signal scales directly with depth. The stress scales less significantly with depth. As a result deep dents will display a ‘geometry’ signature while in shallow dents the stress signature will dominate. In the finite element analysis work, stress was incorporated by modifying the magnetic permeability in the residual stress regions of the modeled dent. Both stress and geometry contributions to the MFL signal were examined separately. Despite using a number of simplifying assumptions, the modeled results matched the experimental results very closely, and were used to aid in interpretation of the MFL signals.

Sign in / Sign up

Export Citation Format

Share Document