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This study aims to predict dynamic responses of aileron and spoiler control surfaces in subsonic flight via the use of surrogate models. The prepared reduced order models prove useful when quick estimations for a large number of variations are required.

The linear frequency domain (LFD) method was used for the simulation study. Each surrogate contained a database of 100 control surface dynamic responses over a spectrum of 200 harmonics computed with LFD. To interpolate new results, the DLR surrogate modelling toolbox, SMARTy, was used. The database’s samples were prepared in a Halton sequence, making interpolation reliable. The surrogate’s parameter space was the Mach number, Reynold’s number, angle of attack, control surface deflection angle and the control surface chord length.

The LFD method proved effective for the mentioned purpose: the surrogates were accurate, up to 15% of relative error, in reproducing dynamic responses of aileron and spoiler deflections at low speed, within the limitations of flow field linearity, as well as surrogate prediction capability. The restrictions of the surrogate, and the reasoning thereof, are also presented in detail in the study. Future load alleviation studies are a potential of the findings here.

LFD is an innovative technique for load prediction and alleviation studies. This paper provides a reference for engineers wishing to use the method for the two mentioned control surfaces, or the like.

To illustrate the benefits of using the empirical similitude method when creating scale models with rapid prototyping processes, particularly in the context of evolutionary product design.

Apply the empirical similitude method in two experimental examples. Utilize rapid prototyping processes to create scale models. Both examples are based on the context of evolutionary product design. For one example, evaluate accuracy of empirical similitude results as compared to traditional similitude.

The first experimental example showed improved accuracy in the empirical similitude results as compared with traditional similitude. The second experimental example illustrated an effective approach for applying the empirical similitude method to a realistic product evolution.

Limited to two experimental examples. Examples involve a single prototyping process (selective laser sintering). Does not cover limitations of the empirical similitude method.

The approach provides for an effective way of utilizing rapid prototypes to predict the functional behavior of an evolutionary product. Rapid prototypes are readily available, but are rarely used in evaluating product function, due to limitations in part sizes and material properties.

This paper provides a practical way of utilizing rapid prototypes to predict the functional behavior of a product through scale models. It also illustrates the proposed method with two experimental examples.

This study aims to develop a new correlation method for prediction of in-flight wings deflections by integration of the experimental ground tests with computational fluid dynamics (CFD) analysis.

The ground test results are implemented in the curve fitting process to determine deflections at 66 specific points (SPs) on the front and rear wing torque box. By using the obtained deflections and the corresponding applied loads, an experimental deflection equation (EDE) for each point is established through the Castigliano’s theorem. The CFD aerodynamic loads of typical aircraft, which have been obtained earlier by the authors, are once again used in the current research. The total applied loads to each part are achieved via summation of inertia and aerodynamic loads. The obtained loads are transformed to the equivalent concentrated loads at the SPs. By substituting the concentrated load values in the EDEs, the SPs deflections are achieved for mentioned flight conditions. The resulted deflections and the corresponding input flight parameters, i.e. M and α, are incorporated into a linear regression method for development of the appropriate in-flight deflection equations (IFDEs). The validity of IFDEs is approved by comparing IFDEs’ deflections with the corresponding ones calculated through EDEs for different flight conditions.

As an alternative approach to the fairly expensive flight tests, the IFDEs can be used to predict the in-flight wing deflections with comparable degree of accuracy.

Prediction of actual wing deflections distributions without flight tests execution at any given flight condition.

This paper aims to investigate the feasibility of supportless printing of lattice structures by metal fused filament fabrication (MF³) of Ti-6Al-4V. Additionally, an empirical method was presented for the estimation of extrudate deflection in unsupported regions of lattice cells for different geometric configurations.

Metal-polymer feedstock with a solids-loading of 59 Vol.% compounded and extruded into a filament was used for three-dimensional printing of lattice structures. A unit cell was used as a starting point, which was then extended to multi-stacked lattice structures. Feasible MF³ processing conditions were identified to fabricate defect-free lattice structures. The effects of lattice geometry parameters on part deflection and relative density were investigated at the unit cell level. Computational simulations were used to predict the part quality and results were verified by experimental printing. Finally, using the identified processing and geometry parameters, multi-stacked lattice structures were successfully printed and sintered.

Lattice geometry required considerable changes in MF³ printing parameters as compared to printing bulk parts. Lattice cell dimensions showed a considerable effect on dimensional variations and relative density due to varying aspect ratios. The experimental printing of lattice showed large deflection/sagging in unsupported regions due to gravity, whereas simulation was unable to estimate such deflection. Hence, an analytical model was presented to estimate extrudate deflections and verified with experimental results. Lack of diffusion between beads was observed in the bottom facing surface of unsupported geometry of sintered unit cells as an effect of extrudate sagging in the green part stage. This study proves that MF³ can fabricate fully dense Ti-6Al-4V lattice structures that appear to be a promising candidate for applications where mechanical performance, light-weighting and design customization are required.

Supportless printing of lattice structures having tiny cross-sectional areas and unsupported geometries is highly challenging for an extrusion-based additive manufacturing (AM) process. This study investigated the AM of Ti-6Al-4V supportless lattice structures using the MF³ process for the first time.

Purpose – This paper proposes a new procedure for measuring affective responses during social interaction using facial thermographic imaging.

Methodology – We first describe the results of several small pilot experiments designed to develop and refine this new measure that reveal some of the methodological advantages and challenges offered by this measurement approach. We then demonstrate the potential utility of this measure using data from a laboratory experiment (N=114) in which we used performance feedback to manipulate identity deflection and measured several types of affective responses – including self-impressions and emotions.

Findings – We find warming of the brow (near the corrugator muscle) and cheek (near the zygomatic major muscle) related most strongly to emotion valence and self-potency, with those whose brows and cheeks warmed the most feeling less positive emotion and less potent self-impressions. Warming in the eye area (near the orbicularis oculi) related most closely to undirected identity deflection and to positive self-sentiments. Positive self-views and strong identity disruptions both contributed to warming of the eyes.

Implications – The rigor of contemporary sociological theories of emotion exceeds our current ability to empirically test these theories. Facial thermographic imaging may offer sociologists new assessments of affect and emotion that are ecologically valid, socially unreactive, temporally sensitive, and accurate. This could dramatically improve our ability to test and develop affect based theories of social interaction.

Industrial robots are extensively used in the robotic assembly of rigid objects, whereas the assembly of flexible objects using the same robot becomes cumbersome and challenging due to transient disturbance. The transient disturbance causes vibration in the flexible object during robotic manipulation and assembly. This is an important problem as the quick suppression of undesired vibrations reduces the cycle time and increases the efficiency of the assembly process. Thus, this study aims to propose a contactless robot vision-based real-time active vibration suppression approach to handle such a scenario.

A robot-assisted camera calibration method is developed to determine the extrinsic camera parameters with respect to the robot position. Thereafter, an innovative robot vision method is proposed to identify a flexible beam grasped by the robot gripper using a virtual marker and obtain the dimension, tip deflection as well as velocity of the same. To model the dynamic behaviour of the flexible beam, finite element method (FEM) is used. The measured dimensions, tip deflection and velocity of a flexible beam are fed to the FEM model to predict the maximum deflection. The difference between the maximum deflection and static deflection of the beam is used to compute the maximum error. Subsequently, the maximum error is used in the proposed predictive maximum error-based second-stage controller to send the control signal for vibration suppression. The control signal in form of trajectory is communicated to the industrial robot controller that accommodates various types of delays present in the system.

The effectiveness and robustness of the proposed controller have been validated using simulation and experimental implementation on an Asea Brown Boveri make IRB 1410 industrial robot with a standard low frame rate camera sensor. In this experiment, two metallic flexible beams of different dimensions with the same material properties have been considered. The robot vision method measures the dimension within an acceptable error limit i.e. ±3%. The controller can suppress vibration amplitude up to approximately 97% in an average time of 4.2 s and reduces the stability time up to approximately 93% while comparing with control and without control suppression time. The vibration suppression performance is also compared with the results of classical control method and some recent results available in literature.

The important contributions of the current work are the following: an innovative robot-assisted camera calibration method is proposed to determine the extrinsic camera parameters that eliminate the need for any reference such as a checkerboard, robotic assembly, vibration suppression, second-stage controller, camera calibration, flexible beam and robot vision; an approach for robot vision method is developed to identify the object using a virtual marker and measure its dimension grasped by the robot gripper accommodating perspective view; the developed robot vision-based controller works along with FEM model of the flexible beam to predict the tip position and helps in handling different dimensions and material types; an approach has been proposed to handle different types of delays that are part of implementation for effective suppression of vibration; proposed method uses a low frame rate and low-cost camera for the second-stage controller and the controller does not interfere with the internal controller of the industrial robot.

The purpose of this study is to develop an analytical model that is capable of predicting the behavior of shear endplate beam-column assemblies when exposed to fire, taking into account the thermal creep effect.

An analytical model is developed and validated against finite element (FE) models previously validated against experimental tests in the literature. Major material and geometrical parameters are incorporated in the analysis to investigate their influence on the overall response of the shear endplate assembly in fire events.

The analytical model can predict the induced axial forces and deflections of the assembly. The results show that when creep effect is considered explicitly in the analysis, the beam undergoes excessive deformation. This deformation needs to be taken into account in the design. The results show the significance of thermal creep effect on the behavior of the shear endplate assembly as exposed to various fire scenarios.

However, the user-defined constants of the creep equations cannot be applied to other connection types. These constants are limited to shear endplate connections having the material and geometrical parameters specified in this study.

The importance of the analytical model is that it provides a time-effective, simple and comprehensive technique that can be used as an alternative to the experimental tests and numerical methods. Also, it can be used to develop a design procedure that accounts for the transient thermal creep behavior of steel connections in real fire.

Numerical models are being increasingly relied upon to evaluate wind turbine performance by simulating phenomena that are infeasible to measure experimentally. These numerical models, however, require a large number of input parameters that often need to be calibrated against available experiments. Owing to the unavoidable scarcity of experiments and inherent uncertainties in measurements, this calibration process may yield non-unique solutions, i.e. multiple sets of parameters may reproduce the available experiments with similar fidelity. The purpose of this paper is to study the trade-off between fidelity to measurements and the robustness of this fidelity to uncertainty in calibrated input parameters.

Here, fidelity is defined as the ability of the model to reproduce measurements and robustness is defined as the allowable variation in the input parameters with which the model maintains a predefined level of threshold fidelity. These two vital attributes of model predictiveness are evaluated in the development of a simplified finite element beam model of the CX-100 wind turbine blade.

Findings of this study show that calibrating the input parameters of a numerical model with the sole objective of improving fidelity to available measurements degrades the robustness of model predictions at both tested and untested settings. A more optimal model may be obtained by calibration methods considering both fidelity and robustness. Multi-criteria Decision Making further confirms the conclusion that the optimal model performance is achieved by maintaining a balance between fidelity and robustness during calibration.

Current methods for model calibration focus solely on fidelity while the authors focus on the trade-off between fidelity and robustness.

The purpose of this study is to propose an improved design of PneuNets bending actuator which aims at obtaining larger deflection with the same magnitude of pressure. The PneuNets bending actuator shows potential application in the morphing trailing edge concept.

Finite element method is used to investigate the characteristics of the improved design bending actuator. Multiobjective optimal design of the PneuNets bending actuator is proposed based on the Gauss process regression models.

The maximum deflection is obtained when the height of the beams is smaller than half the height of the chambers. The spacing between chambers (beam length) has little effect on the deflection. Larger spacing could be used to reduce the actuator weight.

With the same pressure magnitude, the deflection of the improved design bending actuator is much larger than that of the baseline configuration. PneuNets bending actuator could increase the continuity of the aerodynamic surface compared to other actuators.

The purpose of this paper is to present an overview of the aircraft design problems which can be efficiently solved using a special solid finite‐element model of variable density.

Optimization algorithms based on fully‐stressed design philosophy, sensitivity coefficients, and employing material density as a design variable provide means to generate optimal topology layouts, subject to a wide range of design constraints. A novel non‐dimensional criterion is used for assessment of load‐carrying efficiency of structures and knowledge accumulation.

Variable density model, together with non‐dimensional criterion of structural efficiency, yields a new versatile approach to a structural weight estimation at early design stages. New weight equations are used. The approach is a powerful tool for addressing complex multidisciplinary design optimization (MDO) problems such as aerodynamic load prediction taking aeroelastic deformations into account and aerodynamic‐structural design optimization of unconventional aircraft configurations.

For accurate estimation of wing weight and deflections, the method should be tuned by regression analysis of existing aircraft to properly account for secondary structural weight.

The developed software tools for aeroelastic behaviour prediction and coupled aerodynamic‐structural design optimization are ready for integration into the complex MDO framework.

The variable density model is shown to have broad predictive opportunities for design problems at early stages of a product development.