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In cooperation with the world’s second largest manufacturer of beverage cartons (SIG Combibloc®) for liquid foodstuffs an innovative off-take for neutralisation of reactive gas in a paper laminating machine was constructed. A great challenge during engineering work was ensuring a high concentration of the reactive gas where needed and at the same time minimising work place impact in a machine basically without housing. Preliminary 2D-models of the machine geometry proved to be insufficient in describing all the governing flow phenomena. A simplified 3D-geometry containing all important parts of the complex machinery was necessary for accurate predictions. It was found that the driving force of air movement and transport of reactive gas (which acts as an adhesive agent) from the reaction zone in the interior of the laminating machine to the outside is a boundary flow caused by the rapid movement of carton material and rotating cylinders. A physically correct simulation result of the boundary flow is a premise for correct prediction of air flow in and around the machinery. Lacking experimental data (due to an inaccessible geometry) a worst case scenario was constructed by generating a grid and using turbulence models that maximised mass transport in the boundary layer region and thus emission of (tracer)gas from the machine. CFD simulations were done using the geometry preprocessor Gambit ™ , and the finite volume solver Fluent ™ . The results of the analysis of the emission paths from the machine were surprising and led to the construction of an effective off-take relatively far away from the emission source. The chosen position ensures low disturbance of highly sensitive flow patterns inside the machine and diffusive mixing, dilution and contamination of the surroundings. The effect of the new off-take is an immediate and significant rise in air quality in the vicinity of the laminating machine and ensures maximum allowed concentration in the plant area. The product quality furthermore is uncompromised by the working off-take which was another important goal of this work.

A shape optimization problem for incompressible flows within a stabilized finite element framework is studied. The goal is to develop and test numerical realizations of optimal shape design problems that could be applied to non-trivial industrial problems. The resulting algorithm is applied to the optimization of the geometry of a tapered header in a paper machine headbox. Copyright © 2000 John Wiley & Sons, Ltd.

This paper focuses on the study and optimization of binding machine's paper punching system, especially on the required actuating torque. The mechanical properties of paper, which are required to perform numerical simulation, are revised from current bibliography. Various hole types, required for the different binding systems are analyzed as well as the puncher's geometry. The actuating mechanisms responsible for the punching movement from several binding machines are presented. Torque measurements were performed to demonstrate the potential improvements from a new puncher configuration and/or actuating mechanism., The support from ACCO Brands Portuguesa, Lda is acknowledge. The authors would like to thank the Materials Testing Laboratory for the required testing., info:eu-repo/semantics/publishedVersion

A mathematical model was developed to predict the plateau stress of axially loaded paper honeycombs in various humidity environments. It is a simple formula relating the plateau stress to the thickness-to-length ratio of a honeycomb cell, the yielding stress of a cell-wall material tested under a controlled atmosphere [23°C and 50% relative humidity (RH)] and the ambient RH. Paper honeycombs with various thickness-to-length ratios were researched under several levels of RH, and the plateau stress of each kind of paper honeycomb was obtained. The created model was then verified by comparing the predictions with observations. A good agreement between them corroborates the feasibility and accuracy of the model. Predictions by the present model and those by empirical relations were compared as well. A better prediction was obtained using the present model for a wide range of thickness-to-length ratios, suggesting that the present model can replace empirical formulas to provide more accurate and effective predictions of the plateau stress for paper honeycombs. The proposed method can be used to characterize the energy-absorption properties of paper honeycombs in an actual logistic environment, and so can be used to optimize the structural design of paper honeycombs. Copyright © 2010 John Wiley & Sons, Ltd.

This is an investigation of the effect of paper-yellowing inhibitors on the viscosity-temperature dependence; scatter particle size, and the associated changes in the surface microstructure. The temperature has no effect on the qualitative viscosity behavior of the coating formulation including inhibitors. Particles size of pigment increases with the combination of UV absorber and radical scavenger. Transmission Electron Microscopy shows the microstructure of increasing agglomerations with added inhibitors to coating mixture. Numerical 3D simulation of the flow in the coating nip of metering size press taking inertia forces into consideration depicts vortex formations on the surface of the coater's rolls.

Theoretical analysis was carried out on the engagement process of a paper based wet clutch. The annular multidisk clutch in a SAE#2 tester was chosen as an example. The average flow model on partial hydrodynamic lubrication proposed by Patir and Cheng was employed for the analysis of squeeze motion taking the permeability, the compressive strain, and the asperity contact of paper facing into account. Simultaneously, the equations of heat conduction were solved to calculate the viscosity reduction due to frictional heat generation. The theoretical torque curve agreed qualitatively with the experimental one in spite of the many assumptions made in this analysis.

A generic code DYNTECC has been adapted to perform a parametric study of the effect of inlet flow distortion on the stability of the Pratt and Whitney TF30 engine. This code was developed at Arnold Engineering Development Center, USA, for single and dual spool systems. It was modified at AMRL to accommodate the particular geometry of the TF30 engine. The stage characteristics needed to operate DYNTECC were derived from experimental data for the fan and low-pressure compressor. For the high-pressure compressor they were derived using the STGSTK code developed at NASA Lewis Research Center. This program was modified at AMRL to include real flow effects that were in turn derived using yet another adapted code, CASCAD. The code was primarily used at AMRL to predict the onset of system instability due to simulated full-face rapid inlet temperature ramps typical of those caused during armament firings. It was also run with sinusoidal total pressure oscillations of varying amplitudes and frequencies at the inlet. The code predictions were compared with available data whenever possible, and were found to be consistent with the observed experimental trends.

An overview of the contributions made at the Particle Technology Forum in the general context of multiphase flow research is presented. Recent developments in the measuring and computational simulation techniques have made significant inroads in the field. There is an increased interest on basic two-phase flow mechanisms, particularly for dense suspension flows. The numerical simulations are more sophisticated and closer to industrial design and applications. Rapidly changing technologies provide support for the non-intrusive instrumentation and on-line technology for two-phase flow. The necessity to combine experimental, theoretical and numerical simulation techniques in most research projects has highlighted the importance of a broader university education and the use of interdisciplinary research teams. Several open research issues have been identified.

Numerical simulation of history-dependent curl has been made on the basis of the viscoelastic laminate model [5]. Curl behavior of paper under varying humidity conditions depends not only on the present value of moisture content but also on the moisture history that paper has experienced in the past, such as typically seen in Figs. 1 to 3. In order to predict such complex curl behavior, a computer simulation model was developed by using the classical lamination theory and the general linear theory of viscoelasticity which was proposed by Coleman [4]. Drying stress effects were incorporated by assuming presence of stresses in the reference state, which was taken in the final drying stage [5].Simulation results for curvature response to repeated humidity cycling showed that the paper curl can be separated into two components, i. e., reversible and irreversible componets. The reversible component is essentially determined by difference in hygroexpansion coefficients between top and bottom sides of the sheet, whereas the irreversible curl is governed mainly by mechanical causes, i. e., asymmetric distribution of drying stresses and two-sidedness in relaxation moduli. When the top and bottom sides of the sheet are subjected to different moisture histories and returned to the original uniform moisture distribution, such as often seen in printing and xerography processes, paper shows residual curl after the process in the absence of non-uniformity in paper properties in the thickness direction. This phenomenon is caused by viscoelastic relaxation of hygro-stress gradient which is produced during the process. In this case it is, therefore, important to control the “average” values of hygroexpansion coefficients and relaxation moduli through the thickness, as well as the two-sidedness of these properties.Since paper curl is a complex manifestation of different effects of non-uniformity, a measure for curl control varies with practical situations. The computer simulation model developed in this study provides a rational design tool for various paper products by clarifying each contribution of the different curl mechanisms.

Thoracic endovascular aortic repair (TEVAR) has been accepted as the mainstream treatment for type B aortic dissection, but post-TEVAR biomechanical-related complications are still a major drawback. Unfortunately, the stent-graft (SG) configuration after implantation and biomechanical interactions between the SG and local aorta are usually unknown prior to a TEVAR procedure. The ability to obtain such information via personalised computational simulation would greatly assist clinicians in pre-surgical planning. In this study, a virtual SG deployment simulation framework was developed for the treatment for a complicated aortic dissection case. It incorporates patient-specific anatomical information based on pre-TEVAR CT angiographic images, details of the SG design and the mechanical properties of the stent wire, graft and dissected aorta. Hyperelastic material parameters for the aortic wall were determined based on uniaxial tensile testing performed on aortic tissue samples taken from type B aortic dissection patients. Pre-stress conditions of the aortic wall and the action of blood pressure were also accounted for. The simulated post-TEVAR configuration was compared with follow-up CT scans, demonstrating good agreement with mean deviations of 5.8% in local open area and 4.6 mm in stent strut position. Deployment of the SG increased the maximum principal stress by 24.30 kPa in the narrowed true lumen but reduced the stress by 31.38 kPa in the entry tear region where there was an aneurysmal expansion. Comparisons of simulation results with different levels of model complexity suggested that pre-stress of the aortic wall and blood pressure inside the SG should be included in order to accurately predict the deformation of the deployed SG.

Numerical simulation of pulp flow in rotating and non-rotating grooves is carried out to investigate the effect of pulp rheological properties and groove geometry on the rotational motion of the pulp flow. The eucalyptus pulp suspension is considered as a working fluid in the present study whose apparent viscosity correlation is available from the experimental measurements reported in the literature. The simulations are carried out with OpenFoam for different values of pulp material, fiber concentrations, and groove cross-section. Helicity is introduced to measure the turnover rate of pulp flow in the groove due to the importance of such motion on the final properties of the pulp flow. A measurement of helicity magnitude and its distribution along the groove revealed that a change in the pulp material would significantly affect the flow structures within the groove. Further investigation on the effects of fiber concentration, c, showed that this parameter does not have a significant effect on the averaged helicity magnitude for c = 2.0 and 2.5, whereas the helicity distribution over the groove cross-section changes clearly for c = 1.5. The results showed that the helicity level is negligible for almost half of the cavity cross-section in the non-rotating groove simulations, which can be considered as a shortcoming of the original geometry of the groove. Therefore, a smaller cross-section for the groove is considered through which an enhancement in the helicity magnitude is observed.

The internal architecture of the femur and its fracture behaviour vary greatly between subjects. Femoral architecture and subsequent fracture risk are strongly influenced by load distribution during physical activities of daily living. The objective of this work is to evaluate the impact of outer cortical surface shape as a key affector of load distribution driving femoral structure and fracture behaviour. Different femur cortical shapes are generated using a statistical shape model. Their mesoscale internal architecture is predicted for the same activity regime using a structural optimisation approach previously reported by the authors and fracture under longitudinal compression is simulated. The resulting total volume of bone is similar in all geometries although substantial differences are observed in distribution between trabecular and cortical tissue. Greater neck-shaft and anteversion angles show a protective effect in longitudinal compression while a thinner shaft increases fracture risk.

Critical-sized bone defects are critical healing conditions that, if left untreated, often lead to non-unions. To reduce the risk, critical-sized bone defects are often treated with recombinant human BMP-2. Although enhanced bone tissue formation is observed when BMP-2 is administered locally to the defect, spatial and temporal distribution of callus tissue often differs from that found during regular bone healing or in defects treated differently. How this altered tissue patterning due to BMP-2 treatment is linked to mechano-biological principles at the cellular scale remains largely unknown. In this study, the mechano-biological regulation of BMP-2-treated critical-sized bone defect healing was investigated using a multiphysics multiscale in silico approach. Finite element and agent-based modeling techniques were combined to simulate healing within a critical-sized bone defect (5 mm) in a rat femur. Computer model predictions were compared to in vivo microCT data outcome of bone tissue patterning at 2, 4, and 6 weeks postoperation. In vivo, BMP-2 treatment led to complete healing through periosteal bone bridging already after 2 weeks postoperation. Computer model simulations showed that the BMP-2 specific tissue patterning can be explained by the migration of mesenchymal stromal cells to regions with a specific concentration of BMP-2 (chemotaxis). This study shows how computational modeling can help us to further understand the mechanisms behind treatment effects on compromised healing conditions as well as to optimize future treatment strategies. ispartof: BIOMECHANICS AND MODELING IN MECHANOBIOLOGY vol:20 issue:4 pages:1627-1644 ispartof: location:Germany status: published

Penetration of a flexible and steerable needle into a soft target material is a complex problem to be modelled, involving several mechanical challenges. In the present paper, an adaptive finite element algorithm is developed to simulate the penetration of a steerable needle in brain-like gelatine material, where the penetration path is not predetermined. The geometry of the needle tip induces asymmetric tractions along the tool–substrate frictional interfaces, generating a bending action on the needle in addition to combined normal and shear loading in the region where fracture takes place during penetration. The fracture process is described by a cohesive zone model, and the direction of crack propagation is determined by the distribution of strain energy density in the tissue surrounding the tip. Simulation results of deep needle penetration for a programmable bevel-tip needle design, where steering can be controlled by changing the offset between interlocked needle segments, are mainly discussed in terms of penetration force versus displacement along with a detailed description of the needle tip trajectories. It is shown that such results are strongly dependent on the relative stiffness of needle and tissue and on the tip offset. The simulated relationship between programmable bevel offset and needle curvature is found to be approximately linear, confirming empirical results derived experimentally in a previous work. The proposed model enables a detailed analysis of the tool–tissue interactions during needle penetration, providing a reliable means to optimise the design of surgical catheters and aid pre-operative planning. Electronic supplementary material The online version of this article (10.1007/s10237-020-01310-x) contains supplementary material, which is available to authorised users.

The mechanical characterization of brain tissue is a complex task that scientists have tried to accomplish for over 50 years. The results in the literature often differ by orders of magnitude because of the lack of a standard testing protocol. Different testing conditions (including humidity, temperature, strain rate), the methodology adopted, and the variety of the species analysed are all potential sources of discrepancies in the measurements. In this work, we present a rigorous experimental investigation on the mechanical properties of human brain, covering both grey and white matter. The influence of testing conditions is also shown and thoroughly discussed. The material characterization performed is finally adopted to provide inputs to a mathematical formulation suitable for numerical simulations of brain deformation during surgical procedures.

Pulp pump plays an important role in the transportation process of pulp and paper making industry. A CFD based investigation toward pump performance optimization was performed by using the commercial package CFX15.0. To improve accuracy, the grid irrelevance was examined by employing different mesh sizes. In addition, the simulations were performed at steady state with the RNG k-e model. The comparisons between numerical and experimental results of the originally designed pump were further analyzed. it was showed that the head and efficiency were much lower than the expected performances. To optimize the pump performance, the Design of Experiments (DOE) method was further applied to improve the originally designed pump. The experiments with different outlet blade angles, impeller suction eye diameters, and volute widths were conducted. The results showed that the performance of the pump with smaller impeller inlet diameter and smaller volute inlet width was comparatively better. In addition, the head and efficiency was increased a little by increasing the blade outlet angle appropriately.

The buckling behaviour of corrugated paper packages was studied by means of an experimental and theoretical analysis. Mechanical behaviour of paperboard was first evaluated experimentally, then a local geometry FEM model, able to reproduce with a very good accuracy buckling loads obtained experimentally in the standard edge compression test, was developed. In order to investigate the buckling of a complete package, a finite element ‘corrugated board’ was introduced by means of a dedicated homogenization procedure. The FEM model of the package, assembled with this new element, can accurately predict the experimental data of incipient buckling observed during the standard box compression test, despite the few degrees of freedom and the minimal computational effort. Copyright © 2003 John Wiley & Sons, Ltd.

The numerical simulation of an integrated, liquid-fuelled ramjet engine comprising supersonic air intake, subsonic combustor and a convergent-divergent nozzle has been carried out and the results are discussed in this paper. These results include cold flow studies, heat addition in the combustor and full engine analysis with coupled simulation of supersonic air-intake and combustion chamber along with the nozzle. Overall ramjet operation depends on the performance of the air intake and the combustion chamber. The coupling phenomena are very dominant and performance of air intake is affected vastly by the combustor operation and vice versa. In this paper, a numerical analysis of integrated liquid ramjet engine considering coupling phenomena between various sub-systems viz., air intake, combustor and nozzle has been reported. � 2008, DESIDOC.

3D thermal-mechanical coupled numerical simulation of heat pulp mould was carried out. The numerical simulation result shows the rising up process of mould temperature. Temperature distribution contours shows the temperature status on the mould. Temperature distribution results provide reliable guarantee to change the mould structure, so that the temperature distribution on surface becomes uniform. Displacement contours show the mould deformation under the coupled effect of hot temperature and mechanical pressure. The displacement value of nodes can offer reference size to scale mould at the design stage. As a result, high accuracy mould will be manufactured, and this will improve the passing rare of product.

A goal function approach is used to derive an extension of Murray’s law that includes effects of nonlinear mechanics of the artery wall. The artery is modeled as a thin-walled tube composed of different species of nonlinear elastic materials that deform together. These materials grow and remodel in a process that is governed by a target state defined by a homeostatic radius and a homeostatic material composition. Following Murray’s original idea, this target state is defined by a principle of minimum work. We take this work to include that of pumping and maintaining blood, as well as maintaining the materials of the artery wall. The minimization is performed under a constraint imposed by mechanical equilibrium. We derive a condition for the existence of a cost-optimal homeostatic state. We also conduct parametric studies using this novel theoretical frame to investigate how the cost-optimal radius and composition of the artery wall depend on flow rate, blood pressure, and elastin content. At the time for thesis presentation publication was in status: ManuscriptFunding Agencies|Swedish Research Council [621-2012-3117]

Laboratory flotation rate measurements were made on site using pulp generated in an operating plant. The purpose of the measurements was to design an optimized flotation circuit to improve the plant performance. The laboratory tests, which included a locked cycle test, indicated that substantial improvements in the plant circuit were possible. There was excellent agreement between the numerically simulated and the experimentally simulated material balances.

In this paper based on the experiment principle of evaluating adhesion property by scratch testing, the peeling mechanism of thin films is discussed by applying contact theory and surface physics theory. A mathematical model predicting the critical load is proposed for calculating critical load as determined by scratch testing. The factors for correctly evaluating adhesion of coatings according to the experimental data are discussed.

Automobile compartments arc exposed to unstable heat loads due to solar radiation, combined convection, conduction and radiation beat transfer through the cabin surfaces, air exchange and metabolic heat production of the occupants. In this study, a dynamic model of the heat loads that affect the thermal behaviour of the automobile compartment was developed in a Matlab-Simulink environment. Solar irradiation on cabin surfaces and thermal interactions between the driver and cabin interior can be calculated by the model. In order to determine mean radiant temperature and direct solar irradiation absorbed by the driver, view factors between the person and the interior surrounding surfaces were obtained by using a 3-D CFD model of cabin and driver. Experiments were also performed and the simulation results were compared with the measured and the obtained experimental data available in the literature. The effects of colour (white and black) and windows' optical properties (transmissivity, reflectivity and absorptivity coefficients) oil the thermal comfort were also investigated.

This paper deals with the use of the numerical computer oriented method for the analysis and verification of the design of workpiece clamping. The inaccuracies of the positioning in clamping locating points were simulated using the FEM software ANSYS. The influence of inaccuracies in the positions of contact locating points on the displacements of the workpiece characteristic points and their position in clamped removable jaws was examined. The reaction forces in the contact locating points were also computed and analyzed.

Purpose Surface coatings have been introduced on the contact surfaces to protect the mechanical parts for a long time. However, in terms of the optimum design of coatings, some key coating parameters are still selected by trial and error. The optimum design of coatings can be conducted by numerical experiments. This paper aims to predict the contact behavior of the coated rough surfaces accurately. One improved asperity contact model for the coated rough surfaces considering the misalignment of asperities would be developed. Design/methodology/approach Incorporating the coated asperity contact model into the improved Greenwood Tripp-based statistical approach, the proposed model can predict the elastic-plastic behaviors of the interacting coated asperities. Findings According to numerical experiments, compared with the coated asperity contact model in which an equivalent rough surface against a plane is assumed, the improved asperity contact model for the coated contacts can account for the effect of permitting misalignment of two rough surfaces. The contacts having the thicker, stiffer and harder coatings result in higher asperity contact pressure and smaller real contact area fraction under the given Stribeck oil film ratio. Originality/value In this paper, one statistical coated asperity contact model for two rough surfaces was developed. The developed model can consider the elastic-plastic behavior of interacting coated asperities. The effects of the coating thickness and its mechanical properties on the contact behavior of the rough surfaces with coatings can be evaluated based on the developed model.

Ignition and flame inception are well recognised as affecting performance and stable operation of spark ignition engines. The very early stage of combustion is indeed the main source of cycle-to-cycle variability, in particular in gasoline direct injection (GDI) engines, where mixture formation may lead to non-homogenous air-to-fuel distributions, especially under some speed and load conditions. From a numerical perspective, 3D modelling of combustion within Reynolds Averaged Navier Stokes (RANS) approaches is not sufficient to provide reliable information about cyclic variability, unless proper changes in the initial conditions of the flow transport equations are considered. Combustion models based on the flamelet concept prove being particularly suitable for the simulation of the energy conversion process in internal combustion engines, due to their low computational cost. These models include a transport equation for the flame surface density, which needs proper initialization. A flame collocation is indeed to be properly made when starting the calculations, often just based on the user's skill and without resorting to any quantitative data derived from experiments. However, the way to define initial conditions for cyclic variability prediction is often based on just statistical considerations. This work aims at exploiting information derived from images collected in a single cylinder 4-stroke GDI engine to properly collocate the flame at the start of the combustion calculation. The considered engine is optically accessible through a wide fused-silica window fixed on the piston crown having a Bowditch design. Image processing methodologies are applied to evaluate local and integral luminous intensity, and flame morphology parameters. The collected data allows improving the numerical simulation and gaining hints about the main parameters defining the engine cyclic variability.

In this paper, aiming at focusses on many problems existing in the mathematical model of temperature change in the low-pressure casting solidification process of aluminum alloy wheel hub, there is a big gap between the simulation and the actual temperature change, which affects the research on the solidification defects of the wheel hub. In order to study the solidification behavior of aluminum alloy hub in low-pressure casting process, the mathematical model describing the temperature change in the process of casting solidification is established by using different solidification latent heat methods. through finite element simulation and experiment, the temperature change in the process of aluminum alloy (A356) solidification is obtained to compare the difference between the temperature change described by different mathematical models, simulation and experiment. The results show that the temperature numerical model of "the temperature compensation heat capacity method" proposed in this paper is most consistent with the simulation temperature change during the solidification process of the aluminum alloy wheel in the simulation mold, which lays a good theoretical foundation for the study of the low-pressure casting process of the aluminum alloy wheel hub.

Purpose This paper aims to solve the lubrication failures in the turning arm bearing of RV reducer, give some help in perfecting the bearing structure design and provide theoretical basis for the reducer’s performance improvement. Design/methodology/approach The paper establishes a mixed lubrication analysis model to study performance parameters. According to the discretization of parameters and iteration of equations, numerical simulation and theoretical analysis are achieved in computational process. Findings Considering influences of contact load, real rough surface and realistic geometry of RV reducer turning arm roller bearing, the mixed lubrication analysis model is established to study the ratio of oil film thickness, pressure distribution and maximum von Mises stress in different speeds, temperatures and fillets. The results of mixed lubrication show that reasonable round corner modification, increase in temperature and speed, decrease of surface roughness and lubricant types can improve the lubrication performance. Originality/value The mixed lubrication analysis model is established to study the influences of contact load, real rough surface and realistic geometry of RV reducer turning arm roller bearing. Different speed, temperature, lubricant and fillet modification are also considered in the research to analyze oil film thickness, pressure distribution and maximum von Mises stress. These studies can optimize structural design of bearing and direct engineer operations.

The response of cold-formed steel roof trusses undergoing large deformations resulting from unconventional loading is not totally known. Roof truss end-connections are one structural component that can cause premature failure. This paper investigates the failure capacities and the energy absorption capabilities of roof truss end-connections. Experimental tests were performed to obtain the capacities of these connections under quasi-static vertical and horizontal (tension and shear) loadings. Numerical simulations were developed to predict the connection response to failure for any configuration. Implicit and explicit dynamic procedures were used in the analysis of the numerical simulations. A deformable screw behavior with failure criterion was used in the numerical modeling to predict the progressive failure of the connection. The paper includes four verifications that validate the deformable behavior of #10 TEK screw used in the simulations. Results showed that the toughness (energy absorbed to failure) of the end-connection is greatly affected by the screw configuration and the direction of loading.

Fluids that are infused into the human body must be at a temperature that is compatible with the internal thermal state of the body. Since infusants are typically stored at temperatures that are too low for compatibility, a heating means is required to achieve the appropriate infusion temperature. This paper sets forth a synergistic investigation involving coupled experimentation and numerical simulation of the characteristics of one of the main categories of body-fluid heating means. The methodology developed here serves equally well as a design optimization tool. The paper encompasses two stages: (a) an experimental and numerical evaluation of a generic warming device in common use and (b) a redesign utilizing the same tools to elevate the performance of devices of this category. The numerical simulation dealt with steady and unsteady three-dimensional fluid flow and heat transfer which are endemic to devices of this kind. The two-pronged approach developed here was shown to be capable of coping with an operating feature called stopflow wherein an officiating physician orders an immediate cessation of fluid flow. The thermal events following stopflow are well described by the numerical simulations.

Purpose This paper aims to develop a robust controller to control vibration of a thin plate attached with two piezoelectric patches in the presence of uncertainties in the mass of the plate. The main goal of this study is to tackle dynamic perturbation that could lead to modelling error in flexible structures. The controller is designed to suppress first and second modal vibrations. Design/methodology/approach Out of various robust control strategies, μ-synthesis controller design algorithm has been used for active vibration control of a simply supported thin place excited and actuated using two piezoelectric patches. Parametric uncertainty in the system is taken into account so that the robust system will be achieved by maximizing the complex stability radius of the closed-loop system. Effectiveness of the designed controller is validated through robust stability and performance analysis. Findings Results obtained from numerical simulation indicate that implementation of the designed controller can effectively suppress the vibration of the system at the first and second modal frequencies by 98.5 and 88.4 per cent, respectively, despite the presence of structural uncertainties. The designed controller has also shown satisfactory results in terms of robustness and performance. Originality/value Although vibration control in designing any structural system has been an active topic for decades, Ordinary fixed controllers designed based on nominal parameters do not take into account the uncertainties present in and around the system and hence lose their effectiveness when subjected to uncertainties. This paper fulfills an identified need to design a robust control system that accommodates uncertainties.

In many applications, lightweight structures need to combine outstanding component properties and low weight. Here, fibre-reinforced polymers offer particular advantages, as their material-inherent anisotropic material damping behaviour facilitates the design of lightweight structures with both low sound radiation levels and low mass. At the same time, composite structures often have to fulfil a high level of stiffness and strength. These manifold requirements result in a complex design process with optimisation scenarios often involving contrary objectives in terms of weight, stiffness and sound radiation. Those objectives are in turn accompanied by many different design variables. The aim of the work presented in this paper was therefore to develop a material-specific design strategy for scenarios of this type. The authors developed semi-analytical models for the calculation of structural dynamics and sound radiation in composite structures before combining them with optimisation algorithms in order to perform effective sensitivity analyses. Parametric studies were used to define material-specific input parameters for physical characteristics, which in turn provided a basis for the detailed numerical simulation of the vibro-acoustic behaviour of complex geometries. This paper uses a trough-shaped structure as an application-oriented example of the optimisation of vibro-acoustic behaviour with the aid of the numerical model developed by the authors.

As a major component and work unit of micro gas turbine, the performance of micro turbine directly determines the realizability of micro gas turbine. In order to explore the feasibility, to obtain the performance, and to verify the design results of a micro radial turbine, this paper mainly presents the investigation on overall performance of a micro radial turbine with 10 mm diameter for 50W-class micro gas turbine by the cold model test. Firstly, the aerodynamic performance test platform for high speed micro radial turbine was exhibited. Then, the feasibility and overall performance test of micro radial turbine was carried out. At present, the rotational speed of micro radial turbine has achieved at 359,900 rpm by using hydrostatic gas bearing, which is approximately 80% rotational speed of the design point in cold model test. Thirdly, based on the experimental data and numerical simulation, the operating performance and overall performance of the micro gas turbine were analyzed and discussed in details. The final results indicate that the feasibility of the millimeter-scale micro radial turbine with 10 mm diameter has partly been proven at present level and the micro radial turbine system need to be further improved. These works not only obtain the some valuable experimental data, but also accumulate experience of micro radial turbine design. And this paper not only exhibits the test and design results as engineering reference, but also presents the operation problems and its potential solutions of ultra-high rotational speed experiment and performance test of a micro radial turbine.

This paper deals with the problem of designing a controller for a thrust-propelled vehicle which steers the vehicle to track a 3D spatial path, while effective compensation for both time-varying disturbances and uncertainties is achieved as well. Taking advantage of extraction algorithm, we separate the design for the translational and rotational dynamics. A back-stepping-based controller and a sliding mode controller are, respectively, designed for the translational and rotational dynamics in succession. The stability of the control framework is established through Lyapunov analysis. A numerical simulation is also included in the paper to render the effectiveness of the proposed control scheme.

The reported researches only analyze vibration parameters of the seed-metering device. However, they do not adopt any algorithm to conduct a multi-objective optimization for the vibration performance of the seed-metering device. In this paper, the vibration of the seed-metering device is numerically computed firstly, and the correctness of the computational model is validated by experimental test. Then, some parameters including the plate thickness, inclination angle, excitation source position and supporting leg thickness of the seed-metering device are studied. In this way, those parameters which have serious impacts on the vibration are obtained. Therefore, the vibration performance is tried to optimize using these parameters as the design variables. This paper proposes a novel multi-layer immune algorithm based on genetic algorithms (ML-IGA). In order to further verify validity of the novel ML-IGA model for optimizing the vibration of the seed-metering device, it is compared with the traditional GA model and PSO-GA model. When the iteration of ML-IGA model was conducted to the 156th generation, the predicted error is smaller than the set critical error. Compared with other two kinds of algorithms, the optimized time is reduced. Regarding optimization of the GA model, the vibration amplitudes are increased by 2.49 % and 4.22 % respectively. Regarding optimization of the PSO-GA model, the vibration amplitudes are increased by 9.74 % and 6.024 % respectively. Regarding optimization of the ML-IGA model, the vibration amplitudes are increased by 17.34 % and 6.78 % respectively. Obviously, structures with better performance can be obtained through using the novel ML-IGA model.

Purpose One of the crucial steps in the molded bra production is the process of developing the mold head. The purpose of this paper is to determine the final cups style and size. Compared with traditional development process of the mold head, less time-consuming and a more quantitative method is needed for the design and modification of the mold head. Design/methodology/approach A three-dimensional (3D) numerical model for the simulation of large compressive deformation was built in this paper to research the foam bra cup molding process. Since the head cones have more representative than the mold heads, the male and female head cones were used in the simulation. All of the solid shapes are modeled by using 3D Solid 164 elements as well as an automatic surface-to-surface contact between head cones. Findings Simulation of the foam cup molding process is conducted by inputting different properties of the foam material and stress-strain curves under different molding temperatures. Research limitations/implications In order to simulate the laminated foam moulding process, heat transfer through a layered textile assembly can be studied by using the thermo-mechanical coupled FE model. Practical implications According to the different foam performance parameters under different temperatures along with different head cone shapes, distribution and variation in the stress field can be obtained as well as the ultimate capacity of foam materials. Social implications A computer-aided parametric design system for the mold heads provides an effective solution to improving the development process of mold heads. Originality/value The distribution and variation in the stress fields can be analyzed through simulation, providing a reference for the mold head design.

In the present paper, preliminary steady-state neutronic evaluations are carried out to understand the dynamics of a molten salt reactor. Oak Ridge National Laboratory’s (ORNL) Molten Salt Reactor Experiment(MSRE) is selected for the case study and the system of nuclear codes DRAGON and ARCH are used for lattice and core calculations respectively. DRAGLIB, an open-source group condensed cross-section library compatible with DRAGON is used for transport calculations. Differences in the reactivity values are observed using the two recent libraries namely, JEFF 3.1.2 and ENDF/BVII.1. A reactivity difference of about 4.5 mk, close to a typical beta value for the reactor, is observed for MSRE core using ENDF/BVII.1 and JEFF3.1.2 libraries. This is attributed to the absence of (n,2n) neutron multiplication reaction cross section for Beryllium in the processed JEFF 3.1.2 draglib library. The effect of missing (n,2n) cross-section leads to an underestimated net reactivity. Core calculations for the MSRE are found satisfactory and highlight observations regarding flux and power distribution which were not seen previously in ORNL’s calculations. A study on the reactivity coefficients reconfirm that the graphite temperature coefficient as calculated previously was overestimated due to lack of proper data library. The present paper aims to understand the MSR neutronics and validate numerical simulation methodology as well as benchmark the indigenously developed core code ARCH on molten salt systems. It also emphasizes the effect of beryllium as a neutron multiplier in the fluid fuel for typical MSRs and highlights its importance in the library evaluations and on the computational correctness of the reactivity of molten salt systems.

Purpose The DELTA® beam composite floor system is a recently developed shallow floor type that has seen many applications in contemporary construction. It involves partially encasing DELTA® steel beams in concrete, with the lower flange remaining exposed. Besides the satisfactory behavior of the system at ambient conditions, understanding its response under elevated temperatures is critical in evaluating its overall performance. Despite certification from the manufacturing company that the system has adequate fire resistance, its behavior under fire conditions has neither been investigated to depth nor reported in detail. The purpose of this paper is the detailed numerical investigation of their behavior in fire. For this reason, the finite element method was implemented in this paper to simulate the response of such beams subjected to fire. Material properties were modeled according to the Eurocodes. The coupled thermal-structural parametric analyses involved four different variations of the “shortest” and “deepest” cross-section (eight case studies in total) specified by the manufacturing company. Other simulations of these cross-sections, in which either the thermal expansion or the structural load were not taken into account, were carried out for comparison purposes. Design/methodology/approach The methodology for simulating such systems, which has been successfully implemented and validated against fire test results elsewhere (Maraveas et al., 2012) was also followed here. To investigate the statement made by Maraveas et al. (2014) and the equations proposed by Zaharia and Franssen (2012) that the insulation is not so effective for “short” cross-sections, two beams, one with a D20-200 (Deltabeam Technical Manual, 2013) cross-section (shallowest section) and one with a D50-600 (Deltabeam Technical Manual, 2013) cross-section (deepest section), were simulated in this paper for comparison purposes. Additionally, reasonable assumptions were made for the cross-sectional dimensions not specified by the manufacturer (Deltabeam Technical Manual, 2013) and parametric analyses were carried out to investigate their effect on the structural response of the system. Findings Composite DELTA® beams can achieve fire resistances ranging from 120 to 180 min, depending on the depth and geometry of their cross-section, with deeper sections displaying a better fire response. The intense thermal bowing that occurs when these beams are heated from below has a more pronounced effect, in terms of thermally induced deflections for deeper sections. The satisfactory fire resistance of these beams is achieved due to the action of the concrete encased web and the reinforcement which compensate for the loss of the exposed lower flange. Increasing the thickness of the web in deeper sections improves their fire rating up to 180 min. The thickness of the lower flange affects the fire rating of the beams only in a minor way. Practical/implications The paper describes a numerical methodology to estimate the fire resistance of complex flooring systems.

The present paper deals with free vibration analysis of laminated composite skew plates with and without cut-outs. The experimental investigation along with numerical simulation has been presented in this paper for complete understanding of the dynamic behaviour of laminated skew plates with cut-out. Glass fibre-reinforced laminated composite plates have been prepared by resin infusion process using vacuum bagging technique in the laboratory for experimental analysis. The experimental studies have been carried out on skew composite plates with varying size of cut-out placed at the centre. The numerical analysis has been carried out by developing a computer code in MATLAB. Special attention is drawn on the formulation of mass matrix by considering effect of rotary inertia. The results obtained by the finite element formulation using nine-noded isoparametric plate-bending elements are validated by comparing the results from relevant published literature. The numerical and experimental data are then compared for experimental verification of present investigation. The consistency of mode shapes between experimental and numerical investigations is checked by using modal assurance criteria.

To study the aerodynamic noise characteristics of alternators in vehicles, this paper established a computational model for the aerodynamic noise of an alternator based on computational fluid dynamics (CFD). The alternator adopted a non-scaling model and considered the detailed structure of collectors and other parts. Based on Lighthill acoustic theory, this paper adopted three-dimensional and large eddy simulation (LES) to conduct an unsteady numerical simulation for the flow field around the alternator, and Ffowcs Williams-Hawkings (FW-H) model was then adopted to conduct an unsteady computation for the aerodynamic noise of the alternator in the far field. When the rotational speed of the alternator was 10000 r/min, this paper obtained the aerodynamic noise characteristics of the alternator and the unsteady flow field structure around the alternator. Studied results showed: The main aerodynamic noise sources of the alternator were front fan, rear fan and stator structure; main influence orders of aerodynamic noises were the 6th, 8th, 10th, 12th, 18th, 24th, 30th and 36th orders. Similarly, this paper also conducted an experimental test on the noise of vehicle alternators. The main influence orders of aerodynamic noises of alternators were the 6th, 8th, 10th, 12th, 18th, 24th, 30th and 36th orders, which was consistent with the working condition of numerical simulation. It showed the correctness of computational results in this paper. In addition, this paper adopted the method of vector synthesis and the distribution of fan blades of the alternator to explain the cause of various orders and provided engineering application foundation for further reducing the noise of main orders.

Purpose Lattice Boltzmann method (LBM) has made great success in computational fluid dynamics, and this paper aims to establish an efficient simulation model for the polymer injection molding process using the LBM. The study aims to validate the capacity of the model for accurately predicting the injection molding process, to demonstrate the superior numerical efficiency in comparison with the current model based on the finite volume method (FVM). Design/methodology/approach The study adopts the stable multi-relaxation-time scheme of LBM to model the non-Newtonian polymer flow during the filling process. The volume of fluid method is naturally integrated to track the movement of the melt front. Additionally, a novel fractional-step thermal LBM is used to solve the convection-diffusion equation of the temperature field evolution, which is of high Peclet number. Through various simulation cases, the accuracy and stability of the present model are validated, and the higher numerical efficiency verified in comparison with the current FVM-based model. Findings The paper provides an efficient alternative to the current models in the simulation of polymer injection molding. Through the test cases, the model presented in this paper accurately predicts the filling process and successfully reproduces several characteristic phenomena of injection molding. Moreover, compared with the popular FVM-based models, the present model shows superior numerical efficiency, more fit for the future trend of parallel computing. Research limitations/implications Limited by the authors’ hardware resources, the programs of the present model and the FVM-based model are run on parallel up to 12 threads, which is adequate for most simulations of polymer injection molding. Through the tests, the present model has demonstrated the better numerical efficiency, and it is recommended for the researcher to investigate the parallel performance on even larger-scale parallel computing, with more threads. Originality/value To the authors’ knowledge, it is for the first time that the lattice Boltzmann method is applied in the simulation of injection molding, and the proposed model does obviously better in numerical efficiency than the current popular FVM-based models.