Coupled Analyses Research Articles

A New Pheromone Race of Acrobasis nuxvorella (Lepidoptera: Pyralidae)

The sex pheromone of the monophagous Acrobasis nuxvorella Neunzig (Lepidoptera: Pyralidae) was reported as (9E,11Z)-hexadecadienal (9E,11Z-16:Ald) (Biorg. Med. Chem. 4: 331–339, 1996), and it has since been an effective integrated pest management (IPM) tool for monitoring this pest in the United States, but not in Mexico. Field and laboratory studies were conducted to confirm that the species in Mexico was indeed A. nuxvorella and to investigate the pheromone chemistry of the Mexican populations of this species. Initial field trials testing compounds structurally related to the known pheromone component, and blends thereof, indicated that a 100 μg:100 μg blend of (9E,11Z)-hexadecadien-1-yl acetate (9E,11Z-16:Ac):9E,11Z-16:Ald in rubber septa was effective in attracting male moths in Mexico. Coupled gas chromatography-electroantennogram analyses confirmed the presence of these compounds in extracts of pheromone glands of females, and antennae of male moths also responded to the alcohol analog (9E,11Z)-hexadecadien-1-ol (9E,11Z-16:OH). Subsequent field trials of various blends of these three compounds in Mexico showed that 1) both the acetate and aldehyde components were required for optimal attraction of male moths of the Mexican populations, and 2) addition of the alcohol suppressed attraction of males in a dose-dependent manner. Tests with the 1:1 9E,11Z-16:Ac:9E,11Z-16:Ald blend at various sites in the United States showed that this blend attracted some moths, but that moths attracted to 9E,11Z-16:Ald alone were predominant in the population. Furthermore, in preliminary studies the latter seemed not to respond to the blend. These findings indicate that there are two pheromone types of the pecan nut casebearer, and they have major implications for the direct use of these pheromones in pecan IPM.

A Numerical Model of a Reciprocating Rod Seal With a Secondary Lip

A numerical model of an elastomeric reciprocating hydraulic rod seal, with both a primary and a secondary lip, has been developed. It is applicable to cases in which the stroke length is significantly larger than the seal width. Coupled fluid mechanics, contact mechanics, and deformation analyses are applied to each lip. Mass conservation and the pressure of the intervening fluid couple the two lips to each other. The leakage, the film thickness distribution, the fluid and contact pressure distributions, and the friction force are predicted for both the outstroke and the instroke for a typical seal, operating with mixed lubrication.

Thermo-electro-structural coupled analyses of crack arrest by Joule heating

Using the finite element method, thermo-electro-structural coupled analyses of the cracked conducting plate under high electric current have been solved. The crack contact condition and temperature-dependent material properties are considered in this analysis. The crack tip temperature, electric current density factor, stress intensity factor and strain energy density factor are obtained for discussions. Due to high electric current density and Joule heating at the crack tip, a circular melting area may exist around the tip. After cooling, a circular void or hole may occur at the crack tip and the crack arrest is achieved. The crack tip temperature decreases when the crack contact area increases. The proper tensile load is necessary for making the crack open enough and causing high current density at the crack tip and associated crack arrest. On the other hand, the crack tip temperature increases with time by the increasing external current and Joule heating. The values of mode-I stress intensity factor and strain energy density factor decrease with time due to the thermal deformation around the crack tip. Because of the temperature-dependent resistivity, the variation of the electric current density factor is complicated. In addition, it is not easy to create a crack-arrest condition when the crack length relative to the plate width is too small.

An Investigation on the Effect of the Coupled and Uncoupled Formulation on Transient Seepage by the Finite Element Method

2-D transient seepage beneath a dam was investigated by the finite element method. Governing equations were considered in coupled and uncoupled methods. At first stage, the fluid continuity equation for compressible porous media considered as uncoupled. Because of the occurrence of seepage forces, and their interaction with the fluid pore pressure, particularly in high compressible soils, uncoupled methods seem to be far from real conditions. Therefore force equilibrium equations were taken into account by coupling with the fluid continuity equation. Finite element formulation based on Galerkin method. Results of two mentioned methods were compared with steady-state seepage results. Comparing the results of coupled and uncoupled models showed that the time require to reach steady-state condition in coupled model considerably shorter than the uncoupled model. Coupled analyses shows that the effective stress due to seepage forces were smaller than ones calculated by the uncoupled method.

Aerodynamic Characteristics of Bodies of Revolution at Near-Sonic Speeds

pressure distributions, drag, and flow characteristics around a family of sting- mounted truncated parabolic bodies of revolution at near-sonic and low-supersonic speeds by comparisons with an extensive existing wind-tunnel database. The analyses included both inviscid and viscous coupled boundary layer analyses. The investigations also included assessments of wind-tunnel wall interference effects as influenced by the various body geometries and test conditions. Extensive test versus theory comparisons of surface pressure distributions, flowfield pressures, anddrag forces are presented for subsonic through low-supersonic Mach numbers for the family of test configurations. An additional objective of these studies was to demonstrate the value of using existing and even rather historic experimental data. The experimental data used in the current studies were obtained from NACA wind-tunnel tests reported in 1958. ECENT near-sonic and low-sonic boom transport aircraft development studies have sparked a renewed interest in the natureoftheaerodynamicsaboutconfigurationsdesignedtocruiseat near-sonic or low-supersonic speeds. The validity of both the wind- tunnel test facilities and the computational methods are challenged by the characteristics of the flow at near-sonic speeds. The flow disturbances induced by a configuration at near-sonic and low- supersonic speeds extend to very large lateral distances. This presents a significant challenge to obtain interference-free wind- tunnel test data and also greatly increases the required lateral extent of the typical computational domain. Consequently, a number of fundamental aerodynamic studies were conducted to assess the ability of the TRANAIR full potential code to predict pressure distributions, drag, and flow characteristics around a family of sting-mounted truncated parabolic bodies of revolution at near-sonic and low-supersonic speeds by comparisons with an extensive existing wind-tunnel data base (1,2). The analyses includedbothinviscidandviscouscoupledboundarylayeranalyses. The investigations also included assessments of the effects of wind- tunnelwallinterferenceasinfluencedbythevariousbodygeometries and test conditions. The physics of the actual flow characteristics separating behind a truncated body and flowing onto a support sting are not correctly modeled by inviscid computational fluid dynamics (CFD) methods which typically include a constant area wake equal to the base area that trails behind the body. Using an analogy between the separated flowfromtheaftbodytothestingandthatofseparated flowbehinda backward facing step, a simple representation of the wake shape was developed and implemented in the TRANAIR analyses. The total drag for each configuration included the pressure drag obtainedbyintegrationofthepressuredistributions,plustheviscous drag. For the inviscid analyses, the viscous drag was estimated by using flatplateskinfrictiontheory.Theviscousdragestimatesforthe coupled boundary layer viscous analyses were obtained by integration of the calculated local skin friction distribution over the surface area of each body. This report presents the results of the subsonic, near-sonic, and supersonic investigations. An additional objective of these studies was to demonstrate the value of using existing and even rather historic experimental data. The experimental data usedin the current studies were obtained from NACA wind-tunnel tests reported in 1958. The study reported in this paper illustrates a process of using the essential tools of the aerodynamist shown in Fig. 1. These tools include computational fluid dynamics (CFD), experimental fluid dynamics (EFD), simplified fluid dynamics (SFD), visual fluid dynamics (VFD), and the most important tool of all, understanding fluid dynamics (UFD).

Magnet design and optimization: The INFN-Genova experience using ANSYS

ANSYS is a general purpose finite element code that can be used to obtain solutions to a large class of engineering problems involving stress analysis, heat transfer, electromagnetism, fluid flow, as well as many coupled field analyses in one, two or three dimensions. ANSYS is thoroughly effective in tackling all the problems that can be classically dealt with a finite element code. For this reason, the INFN-Genova group adopted ANSYS in 1994, and then followed its evolution and innovation. This paper will highlight the ANSYS most distinguishing features we found out in the last years while designing magnets and electromagnetic devices.

Enabling Coupled Quantitative Genomics and Proteomics Analyses from Rat Spinal Cord Samples

Translational research is progressing toward combined genomics and proteomics analyses of small and precious samples. In our analyses of spinal cord material, we systematically evaluated disruption and extraction techniques to determine an optimum process for the coupled analysis of RNA and protein from a single 5-mm segment of tissue. Analyses of these distinct molecular species were performed using microarrays and high resolution two-dimensional gels, respectively. Comparison of standard homogenization with automated frozen disruption (AFD) identified negligible differences in the relative abundance of genes (44) with all genes identified by either process. Analysis on either the Affymetrix or Applied Biosystems Inc. gene array platforms provided good correlations between the extraction techniques. In contrast, the AFD technique enabled identification of more unique proteins from spinal cord tissue than did standard homogenization. Furthermore use of an optimized CHAPS/urea extraction provided better protein recovery, as shown by quantitative two-dimensional gel analyses, than did solvent precipitation during TRIzol-based RNA extraction. Thus, AFD of tissue samples followed by protein and RNA isolation from separate aliquots of the frozen powdered sample is the most effective route to ensure full, quantitative analyses of both molecular entities.

In situ behaviour of a stiff layered clay subject to thermal loading: observations and interpretation

The paper presents an interpretation of an in situ heating test carried out on Opalinus clay in the Mont Terri underground laboratory. Opalinus clay is a stiff, strongly bedded, Mesozoic clay of marine origin. When subjected to thermal loading, saturated stiff clays exhibit a strong pore pressure response that significantly affects the hydraulic and mechanical behaviour of the material. The observations gathered in the in situ test have provided an opportunity to examine the integrated thermo-hydro-mechanical (THM) response of this sedimentary clay. Coupled THM numerical analyses have been carried out to provide a structured framework for interpretation, and to enhance understanding of THM clay behaviour. Numerical analyses have been based on a coupled theoretical formulation that incorporates a constitutive law especially developed for this type of material. The law includes degradation of bonding by damage. By performing three-dimensional computations, it has been possible to incorporate anisotropy of material parameters and of in situ stresses. The 3D simulation has proved able to furnish a satisfactory representation of the development of the in situ test and of the main observed patterns of behaviour. A sensitivity analysis has also been carried out to examine the potential effect of various key or uncertain parameters. The critical examination of test observations and the results of the numerical analyses have allowed the classification, by differing degrees of significance, of the various coupled phenomena present in the problem.

Coupled field analysis of a piezoelectric bimorph disc in a direct write process

This paper investigates the behavior of a piezoelectric (PZT) bimorph disc within a Direct Write Process. A modified Continuous Inkjet Print (CIJ) method is utilized to selectively deposit a variety of conductive nano particulate materials for building functionally gradient materials (FGM). The spatial and temporal complexity of the novel CIJ based microfabrication process necessitates a computational solution to complement its experimental development. Static and modal coupled field finite element analyses were conducted for determining the operating frequency range of the PZT disc within a CIJ print head. The transient behavior of the PZT disc was subsequently analyzed in a conductive ink environment using a fluid–structure interaction (FSI) algorithm. Finally, parametric studies were conducted to generate empirical expression and to determine the relative importance that the density and kinematic viscosity of fluids had on the excitation behavior of the piezoelectric disc.

Implicit domain decomposition methods for coupled analysis of offshore platforms

AbstractThis work presents the implementation of optimized numerical tools for the coupled analysis of floating platforms for offshore oil exploitation. The focus is on time‐domain, nonlinear dynamic analysis, considering the coupling between the hydrodynamic behaviour of the hull and the structural behaviour of the mooring lines and risers modelled by finite elements (FEs). Some aspects of the formulation and solution of the large‐amplitude equations of motion of the hull of the platform are presented, including a brief description of the hydrodynamic models and calculation of the environmental forces. The main aspects of the formulation for the spatial and time discretization of the structural model for the lines are also discussed. Since coupled analyses may require excessive computational costs, the objective of this work is to present the implementation and application of domain decomposition methods, adapted and specialized for the problem at hand, in order to optimize the efficiency of the computational tool. Two groups of domain decomposition methods are considered: the first is a subcycling technique that takes into account the natural partition that exists between the hull and the lines; the second considers the internal decomposition of the mesh of FEs to represent the mooring lines and risers. The methods are devised having in mind their implementation in computers with parallel architecture. Results of a numerical application are presented in order to assess the performance of the methods. Copyright © 2006 John Wiley & Sons, Ltd.

Fluid-Structure Interaction Analysis of Flow-Induced Deformation in a Two-Phase, Neo-Hookean Marine Egg

Coupled computational fluid dynamics and finite element analyses were used to determine the material properties of the egg and jelly layer of the sea urchin Arbacia punctulata. Prior experimental shear flow results were used to provide material parameters for these simulations. A Neo-Hookean model was used to model the hyperelastic behaviors of the jelly layer and egg. A simple compressive simulation was then performed, to compare the maximum von Mises stresses within eggs, with and without jelly layers. Results of this study showed that (1) shear moduli range from ∼100to160Pa, and ∼40to140Pa for an egg without a jelly layer, and jelly layer itself, respectively; and (2) the presence of the jelly layer significantly reduces maximum von Mises stress in an egg undergoing compression.

독립적으로 모델링된 유한요소 부분구조물 시스템의 통합 연계해석을 위한 이동최소자승 정계접합법의 개발

본 논문에서는 독립적으로 모델링되어 절점 불일치 경계면이 존재하는 유한요소 부분구조물들로 구성된 복합 구조시스템의 통합적인 연계해석을 위해 이동최소자승 경계접합법을 제안한다. 제안된 이론을 합성함수 구성 및 근사화 과정을 통해 설명하고, 새로 제안된 경계접합법의 타당성, 수렴성 및 효율성을 고찰하기 위해 각종 수치실험을 수행한다. 패치 테스트, 수렴성 조사를 통해 제안된 이론의 타당성을 보이고, 각종 통합 연계해석 수치예제를 통해 격자 재생성이나 추가적 미지수의 도입이 필요 없는 이동최소자승 경계접합법의 실제적 효율성을 입증한다. In this paper, a novel moving least squares interface welding method is proposed to carry out the coupled analysis of whole model composed of independently modeled finite element substructures with nodal mismatching interfaces. To verify the validity, and efficiency of the proposed interface welding method, various numerical examples are worked out including patch tests, convergence tests, and examples of coupled analyses of the structural systems with mismatching substructures. From the numerical tests, it is confirmed that one can efficiently carry out the coupled analysis of whole model composed of mismatching finite element substructures through the proposed method without any remeshing or any additional unknown.

Efficient Handling of Implicit Entities in Reduced Mesh Representations

State-of-the-art numerical analyses require mesh representation with a data structure that provides topological information. Due to the increasing size of the meshes currently used for simulating complex behaviors with finite elements or boundary elements (e.g., adaptive and/or coupled analyses), several researchers have proposed the use of reduced mesh representations. In a reduced representation, only a few types of the defined topological entities are explicitly represented; all the others are implicit and retrieved “on-the-fly,” as required. Despite being very effective in reducing the memory space needed to represent large models, reduced representations face the challenge of ensuring the consistency of all implicit entities when the mesh undergoes modifications. As implicit entities are usually described by references to explicit ones, modifying the mesh may change the way implicit entities (which are not directly modified) are represented, e.g., the referenced explicit entities may no longer exist. We propose a new and effective strategy to treat implicit entities in reduced representations, which is capable of handling transient nonmanifold configurations. Our strategy allows, from the application point of view, explicit and implicit entities to be interchangeably handled in a uniform and transparent way. As a result, the application can list, access, attach properties to, and hold references to implicit entities, and the underlying data structure ensures that all such information remains valid even if the mesh is modified. The validity of the proposed approach is demonstrated by running a set of computational experiments on different models subjected to dynamic remeshing operations.

Identification of the Sex Pheromone of the Swede Midge, Contarinia nasturtii

Coupled gas chromatographic-electroantennographic detection analyses of ovipositor extracts of calling Contarinia nasturtii females revealed two compounds that elicited responses from antennae of male midges. Using synthetic reference samples, these components were identified by gas chromatography mass spectrometry and enantioselective GC as (2S,9S)-diacetoxyundecane and (2S,10S)-diacetoxyundecane. In addition, trace amounts of 2-acetoxyundecane were found in ovipositor extracts, and the (S)-enantiomer was synthesized. When tested in the wind tunnel, a blend of 5 ng (2S,9S)-diacetoxyundecane and 10 ng (2S,10S)-diacetoxyundecane (mimicking the ratio found in the extracts) did not attract any of the males tested, but when 0.1 ng (S)-2-acetoxyundecane was added to the blend, 86.8% of the males were attracted to the bait. Three-component blends with lower or higher relative concentrations than 1% of (S)-2-acetoxyundecane [relative to (2S,10S)-diacetoxyundecane] were less attractive. In a field trapping experiment with released laboratory-reared C. nasturtii adults, traps baited with 500:1000:10 ng of (2S,9S)-diacetoxyundecane/(2S,10S)-diacetoxyundecane/(S)-2-acetoxyundecane applied to rubber septa or dental cotton rolls were tested. Traps without dispensers were used as controls. All three treatments were tested at 20 and 50 cm above ground. The estimated recapture rate was 30-50%, and 81.9% of the recaptured males were caught in traps positioned at 20 cm above ground, and 88.4% in traps with dental cotton rolls as dispensers.

Coupled effects in stability analysis of pile–slope systems

A numerical comparison of predictions by limit equilibrium analysis and 3D numerical analysis is presented for a slope–pile system. Special attention is given to the coupled analysis based on the explicit-finite-difference code, FLAC 3D. To this end, an internal routine (FISH) was developed to calculate a factor of safety for a pile-reinforced slope according to a shear strength reduction technique. Coupled analyses were performed for stabilizing piles in a slope, in which the pile response and slope stability are considered simultaneously and subsequently the factors of safety are compared to a solution for a homogeneous slope using an uncoupled analysis (limit equilibrium analysis). Based on a limited parametric study, it is shown that the factor of safety for the slope is less conservative for a coupled analysis than for an uncoupled analysis and thus represents a definitely larger safety factor when the piles are installed in the middle of the slopes and the pile heads are restrained.

Assessment on Integrity of BWR Internals against Impact Load by Water Hammer under Conditions of Reactivity Initiated Accidents

The integrity of the reactor pressure vessel (RPV) head and reactor internals was assessed by means of fluid and fluid-structural coupled analyses to evaluate the water hammer phenomenon arising from postulated high burnup fuel failure under reactivity initiated accident (RIA) conditions. The fluid viscosity effect on the water column burst as well as the complex three-dimensional flow paths caused by a core shroud and standpipes were considered in this study. It is shown that fluid viscosity becomes an influential factor to dissipate impacting kinetic energy. Integrity of the RPV head and the shroud head was ensured with a sufficient level of margin even under these excessively conservative RIA conditions.

膜構造エアロシェルの変形を解析するための多粒子系モデルとその検証

A three-dimensional particle-based membrane model, which is used to predict the shape of the membrane aeroshell with large deformation due to the aerodynamic force acting on the body, is developed. In this model, the elastic forces consisting of the tensile force, shear force, and bending force are considered as well as the aerodynamic force. Thanks to the particle-based formulation, the present model is less complicated and can be solved with small computation time. To check the validity of the model, various problems on the membrane including the Poisson effect, large deformation, buckling and wrinkling are solved and the results are in a good agreement with the analytical solutions. At last, the present method is applied to the re-entry capsule concept with a flare-type membrane aeroshell. Coupled analyses with the Newtonian flow approximation show that the flare-type membrane aeroshell is deformed to concave shape and some longitudinal wrinkles are generated by the aerodynamic force.

Coupled Field Analyses in MEMS With Finite Element Analysis

This paper deals with the design and analysis of a horizontal thermal actuator common in MEMS applications using Finite Element Analysis; with the objective of exploring means to improve its sensitivity. The influence of variables like voltage and the dimensions of the cold arm of the actuator unit were examined by comprehensive, coupled thermal-stress analyses. Simulation results from this study showed that the sensitivity of the actuator increases with the applied voltage as well as the width of the cold arm of the thermal actuator. An important observation made from this study is that the size and thermal boundary conditions at the fixed end of the actuator primarily control the stroke and the operating temperature of the actuator for a given potential difference between cold and hot arms. The coupled field analyses also provided a design tool for maximizing the service voltage and dimensional variables without compromising the thermal or structural integrity of the actuator.

Variational Coupled Loads Analyses: Reducing Risk in Development of Space-Flight Hardware

Before space hardware can be launched, positive structural margins of safety must be demonstrated relative to the booster-supplied math model and forcing functions. To identify appropriate structural loads on which to base such margins, several iterations of coupled loads analyses are typically performed during hardware development. Such analyses are traditionally done with a single payload dynamic math model, derived from finite element models, which are combined to form a booster/payload system-level model. Uncertainty in such analyses, relative to both the hardware's final configuration and its modes of vibration, is most often addressed with uncertainty factors selected without any insight into actual loads sensitivity. With recent advances, the analysis process has been accelerated, allowing for variational coupled loads analyses. Such an analysis can account for possible variations in the final hardware configuration: for example, frequency, weight, presence of comanifested payloads, damping, etc. The results of such a variational analysis are presented. The results demonstrate that the use of uncertainty factors can greatly penalize much of the structure with overly conservative load criterion, while at the same time being unconservative for those structural elements most sensitive to the variations. The conclusion is that the utilization of variational coupled loads analyses can result in both reduced risk and more efficient structural designs.

Coupled and uncoupled analyses of piezoelectric free-edge effect in laminated plates

The present paper considers the effect of electromechanical coupling on the interlaminar stresses and the electric field strengths at free edges of laminated plates with piezoelectric material properties. A comparison of coupled and uncoupled piezoelectric analyses is performed using the finite element method. Two symmetric cross-ply plates and one symmetric angle-ply laminate are investigated under uniaxial tension. It is shown that the interlaminar stresses at the free edge are significantly higher in the coupled case for cross-ply laminates, whereas the coupling effect for the symmetric angle-ply laminate is of minor significance. In addition, the occurrence of electric field strengths with singular character is revealed.