- Dr. Matt Castanier is a Research Mechanical Engineer at the US Army DEVCOM Ground Vehicle Systems Center (GVSC) in Wa... moreDr. Matt Castanier is a Research Mechanical Engineer at the US Army DEVCOM Ground Vehicle Systems Center (GVSC) in Warren, MI. His research interests include powertrain modeling and simulation, multidisciplinary design optimization, and trade space exploration. He received his Ph.D. in Mechanical Engineering from the University of Michigan (UM) in 1995. From 1996 through 2008 he was a member of the research faculty at UM. He joined GVSC in 2008 and was promoted to his current position in 2011. Dr. Castanier has published more than 45 journal articles and over 95 conference papers. He currently serves as the Vice Chair of the SAE Integrated Design and Manufacturing (IDM) Activity.edit
Elicitation of requirements is a critical step in any product development process. An effective elicitation process can lead to capturing more requirements with higher degrees of novelty, variety, and completeness. Current elicitation... more
Elicitation of requirements is a critical step in any product development process. An effective elicitation process can lead to capturing more requirements with higher degrees of novelty, variety, and completeness. Current elicitation techniques such as questionnaires, interviews, focus groups, prototyping, and brainstorming often fail to keep the stakeholders and designers engaged and may face issues, such as lack of stakeholder involvement and poor communication and collaboration. Thus, these techniques become prone to capturing ambiguous or incomplete requirements or even missing some requirements. In recent years, the application of gamification (e.g., leveraging gaming features in non-gaming contexts to create engaging and interactive user experiences) has shown promising effects in improving the motivation and participation of users in different design activities. In this paper, we present the results of a preliminary study on the impacts of gamification features on requirements elicitation activity. An experiment was conducted using two versions of a survey to elicit requirements: (1) a gamified questionnaire and (2) a non-gamified, conventional questionnaire. In both surveys, the participants were asked to generate a list of requirements. The gathered sets of requirements were then analyzed using statistical methods and compared based on three metrics: completeness, variety, and novelty. Our findings suggest that gamification positively impacts participants’ engagement, leading to a greater number of requirements. The preliminary results indicate differences in all three metrics considered here. However, there is no statistical significance in these differences to have confidence in the made observations due to the small sample size. As an initial attempt to investigate the impacts of gamification and how they could be evaluated, our study develops a preliminary understanding of the effects of gamification on requirements elicitation.
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Topology optimization of periodic metamaterials for structural applications usually results in uniformly distributed cells. This paper presents a novel concept designed to better tailor unit cell-based meta-material designs for nonlinear... more
Topology optimization of periodic metamaterials for structural applications usually results in uniformly distributed cells. This paper presents a novel concept designed to better tailor unit cell-based meta-material designs for nonlinear structural applications. First, previous work in the development of a systematic method for the construction and optimization of these advanced materials is reviewed. Results of a previous case study for the design of meta-material backer pads for the wheels of the Abrams tank are presented to provide a platform for the introduction of layer specific dimensional multipliers, dubbed “size factors”. These add an additional layer of complexity for the previously designed homogeneous materials. The methodology behind the size factors is presented and the implementation of the “size factors”, as it pertains to the meta-materials designed using the Modified Unit Cell Synthesis method, is then discussed. Initial assumptions for a final size factor arrangement are presented, prompting the creation of two optimization procedures to compare against one another. Results for both optimizations are obtained and while both show an increase in nonlinearity over the original material, the unorganized arrangement of the parameters results in the most optimal designs, with near zero error between the target and obtained non-linear force-strain relationships.
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Elicitation of requirements is a critical step in any product development process. An effective elicitation process can lead to capturing more requirements with higher degrees of novelty, variety, and completeness. Current elicitation... more
Elicitation of requirements is a critical step in any product development process. An effective elicitation process can lead to capturing more requirements with higher degrees of novelty, variety, and completeness. Current elicitation techniques such as questionnaires, interviews, focus groups, prototyping, and brainstorming often fail to keep the stakeholders and designers engaged and may face issues, such as lack of stakeholder involvement and poor communication and collaboration. Thus, these techniques become prone to capturing ambiguous or incomplete requirements or even missing some requirements. In recent years, the application of gamification (e.g., leveraging gaming features in non-gaming contexts to create engaging and interactive user experiences) has shown promising effects in improving the motivation and participation of users in different design activities. In this paper, we present the results of a preliminary study on the impacts of gamification features on requiremen...
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Tradespace analysis capabilities are critical for organizations either selecting large programmatic efforts or those engaged in providing solutions to major program opportunities. The ability of an organization to effectively use the... more
Tradespace analysis capabilities are critical for organizations either selecting large programmatic efforts or those engaged in providing solutions to major program opportunities. The ability of an organization to effectively use the tradespace in their decision-making process had a substantial impact upon programmatic success. Poorly bounded tradespaces may lead to prototype vehicles (or any other system to be designed) that are ultimately unacceptable due to performance, cost, or technical risk issues. Tradespaces that are over-constrained can unduly limit design options and lead to stagnant designs that are unable to incorporate technical innovations. Most organizations find that tradespace analysis presents numerous challenges, so this research aims to address the evaluation of strengths, weaknesses, and opportunities for improvement within an organization. In this study, we explain how an interview-based process was used to perform this analysis and make recommendations for opp...
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Tradespace analysis and exploration is used to frame a design problem. By taking stock of available technologies, predictions of the performance of a system defined from a combinatorial combination of technologies (from say a... more
Tradespace analysis and exploration is used to frame a design problem. By taking stock of available technologies, predictions of the performance of a system defined from a combinatorial combination of technologies (from say a morphological matrix) can be made. Based on these assessments, tradeoffs between functional performance objectives (often termed simply Functional Objectives or FOs) can be made. The result of these performance tradeoffs or Trades, can then be used to define a target design space for a problem. That design space can then be characterized with criteria to determine the viability of the tradespace and the design problem. However, the cost to develop the morphological matrix for the tradespace can be prohibitive. The tradespace at the US Army DEVCOM Ground Vehicle Systems Center (GVSC) took more than 2 years of effort by multiple staff and technical experts to develop and allows for the consideration of more than 1021 vehicles. To develop enhanced approaches to tr...
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Topology optimization of periodic metamaterials for structural applications usually results in uniformly distributed cells. This paper presents a novel concept designed to better tailor unit cell-based meta-material designs for nonlinear... more
Topology optimization of periodic metamaterials for structural applications usually results in uniformly distributed cells. This paper presents a novel concept designed to better tailor unit cell-based meta-material designs for nonlinear structural applications. First, previous work in the development of a systematic method for the construction and optimization of these advanced materials is reviewed. Results of a previous case study for the design of meta-material backer pads for the wheels of the Abrams tank are presented to provide a platform for the introduction of layer specific dimensional multipliers, dubbed “size factors”. These add an additional layer of complexity for the previously designed homogeneous materials. The methodology behind the size factors is presented and the implementation of the “size factors”, as it pertains to the meta-materials designed using the Modified Unit Cell Synthesis method, is then discussed. Initial assumptions for a final size factor arrangem...
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: The DOEs Vehicle Technologies Office (VTO) initiated the Computer Aided Engineering for Electric Batteries (CAEBAT) activity in FY 2010 and TARDEC joined the efforts to co-sponsor the program with more focus on battery performance at... more
: The DOEs Vehicle Technologies Office (VTO) initiated the Computer Aided Engineering for Electric Batteries (CAEBAT) activity in FY 2010 and TARDEC joined the efforts to co-sponsor the program with more focus on battery performance at extreme conditions and mechanical destructive behavior.
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This thesis investigates localization and dissipation phenomena in disordered nearly periodic structures, as well as the efficient dynamic modeling of a particular class of periodic structures, turbomachinery rotors. The effect of... more
This thesis investigates localization and dissipation phenomena in disordered nearly periodic structures, as well as the efficient dynamic modeling of a particular class of periodic structures, turbomachinery rotors. The effect of structural damping on the dynamics of periodic and nearly periodic structures is examined. Decay rates due to disorder and damping are calculated, and the interaction of the localization and dissipation mechanisms in the forced response is investigated. It is shown that damping increases the overall decay rate but reduces localization. Lyapunov exponents of a system wave transfer matrix are employed to analyze localization in multi-coupled (and as a special case, mono-coupled) disordered structures. The largest Lyapunov exponent is calculated numerically for a representative mono-coupled system, and found to compare well with localization factors found by Monte Carlo methods and perturbation approximations. The Lyapunov exponents are also computed for an example of a disordered bi-coupled system, and compared with wave amplitude decay and wave conversion observed in this system. The physical significance of the Lyapunov exponents is discussed. The standard deviations of the Lyapunov exponents are calculated and used to determine frequency ranges in which localization effects, rather than off-resonance or dissipation effects, are strongest. The modeling of bladed disks in turbomachines is considered. An order reduction method is presented which is capable of generating reasonably accurate, very low order models of mistuned bladed disks, so that forced response Monte Carlo simulations may be performed at a reasonable cost. This technique is based on selected component modes of vibration from a finite element analysis of a single disk-blade sector. An example reduced order model is generated, and the mistuned frequencies and localized mode shapes are found to match closely those of the mistuned finite element model. A transfer matrix is formulated, and a Lyapunov exponent analysis is shown to predict a frequency range where localized modes are found.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/104594/1/9542803.pdfDescription of 9542803.pdf : Restricted to UM users only
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ABSTRACT Modeling and re-analysis techniques are proposed for predicting the dynamic response of complex structures that have suffered damage in one or more of their components. When such damages are present, the model of the healthy... more
ABSTRACT Modeling and re-analysis techniques are proposed for predicting the dynamic response of complex structures that have suffered damage in one or more of their components. When such damages are present, the model of the healthy structure may no longer capture the system-level response or the loading from the rest of the structure on the damaged components. Hence, novel models that allow for an accurate re-analysis of the response of damaged structures are needed in important applications, including damage detection. Herein, such models are obtained by using a reduced order modeling approach based on component mode synthesis. Because the resonant response of a complex structure is often sensitive to component uncertainties (in geometric parameters such as thickness, material properties such as Young's modulus, etc.), novel parametric reduced order models (PROMs) are developed. In previous work, PROMs have been applied for handling uncertainties in a single substructure. Herein, PROMs are extended to the general case of multiple substructures with uncertain parameters or damage. Two damage cases are considered: severe structural deformation (dents), and cracks. For the first damage case, an approximate method based on static mode compensation (SMC) is used to perform fast re-analysis of the vibration response of the damaged structure. The re-analysis is performed through a range of locations and severity levels of the damage. For selected damage locations and levels, the SMC approximation is compared to full finite element analysis to demonstrate the accuracy and computational time savings for the new method. For the second damage case (cracks), the vibration problem becomes nonlinear due to the intermittent contact of the crack faces. Therefore, to estimate the resonant frequencies for a cracked structure, the bi-linear frequency approximation (BFA) is used for cracks of various lengths. Since BFA is based on linear analyses, it is fast and particularly well suited for implementation with PROMs for structural re-analysis. In contrast, most other nonlinear techniques for predicting the dynamic response are computationally intensive and cumbersome. For validating the proposed PROMs, resonant frequencies predicted using BFA and PROMs are shown to agree very well with results obtained using a much more expensive commercial finite element tool.
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Research Interests: Engineering, Structural Engineering, Energy, Numerical Analysis, Optimization, and 14 moreModels, Structures, Damping, Stiffness, Physical sciences, Sound and Vibration, Modification, Displacement, Performance Engineering, Requirements, Statics, Parametric Statistics, Computations, and Parametric analysis
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The maximum blade forced response amplitudes for mistuned turbomachinery rotors are generally much greater than those of their tuned counterparts. However, it is known that the ratio of mistuned to tuned maximum vibration amplitudes, the... more
The maximum blade forced response amplitudes for mistuned turbomachinery rotors are generally much greater than those of their tuned counterparts. However, it is known that the ratio of mistuned to tuned maximum vibration amplitudes, the amplitude magnification, is often largest at a relatively small level of mistuning. Increasing the level of mistuning beyond this critical value actually leads to a decrease in the amplitude magnification. This suggests that it might be beneficial to introduce some level of mistuning into the nominal design of the system intentionally. In this study, the effectiveness of this intentional mistuning strategy is investigated. Intentional mistuning is introduced into the rotor design by varying the nominal blade stiffnesses in harmonic and square-wave patterns. In addition, the unavoidable, random mistuning of the blades is included in the model as usual. The statistics of the forced response are examined for lumped parameter models, as well as for a finite element based reduced-order model of an industrial rotor. For the cases considered, it is found that intentional mistuning can greatly reduce a rotor's sensitivity to random mistuning.
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Recent findings indicate that structural interstage (stage-to-stage) coupling in multi-stage rotors can have a critical impact on bladed disk dynamics by altering significantly the flexibility of the disk. This affects local... more
Recent findings indicate that structural interstage (stage-to-stage) coupling in multi-stage rotors can have a critical impact on bladed disk dynamics by altering significantly the flexibility of the disk. This affects local eigenfrequency veering characteristics, and thus a design’s sensitivity to mistuning. In response to these findings, two reduced order modeling techniques are presented that accurately capture structural interstage coupling effects, while keeping model sizes at practical levels. Both free and forced responses of an example two-stage rotor are examined using novel component-mode-based reduced order modeling techniques for mistuned multi-stage assemblies. Both techniques employ an intermediate multi-stage model constructed by component mode synthesis (CMS), which is further reduced by either: (a) partial secondary modal analyses on constraint-mode partitions; or (b) a full-scale secondary modal analysis on the entire multi-stage CMS model. The introduced techniques are evaluated using finite element results as a benchmark. The proposed reduced order modeling techniques are shown to facilitate accurate multi-stage modeling and analyses with or without blade mistuning, using only computationally inexpensive modal data from a cyclic disk sector and a single blade per stage. It is concluded that the most promising and practically feasible approach may be a combination of approaches (a) and (b), in which secondary modal analyses and truncations are first carried out on disk-blade constraint-mode partitions, followed by a tertiary modal analysis on the resulting multi-stage model. In conclusion, by alleviating the restriction to single-stage analyses, the presented multi-stage modeling techniques will enable engineers to analyze the dynamics of mistuned turbomachinery rotor assemblies with greater confidence.
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The intentional mistiming of blades in order to reduce the forced response amplitudes of turbomachinery rotors is considered. The statistics of the maximum blade response amplitudes for a simple model of a 12-bladed disk are investigated.... more
The intentional mistiming of blades in order to reduce the forced response amplitudes of turbomachinery rotors is considered. The statistics of the maximum blade response amplitudes for a simple model of a 12-bladed disk are investigated. It is shown that the maximum response amplitudes are appropriately modeled by a Type III Weibull distribution. Intentional mistuning is introduced into the model by varying the nominal blade stiffnesses in rotationally periodic patterns. Of the six non-zero harmonics, the first and second harmonics are shown to provide a significant decrease in the maximum amplitudes. A more practical, pseudo-harmonic-two configuration of mistuning is also considered. This pattern requires only two unique blade designs, and it results in an even larger decrease in the maximum response than that provided by the harmonic-two intentional mistuning.
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Research Interests: Engineering, Algorithms, Finite element method, Topology, Sensitivity Analysis, and 15 moreBoundary Element Methods, Automotive Engineering, High Frequency, Simulation, Modelling and simulation, Conceptual Design, Boundary Element Method, Efficiency Analysis, Statistical Energy Analysis, Next Generation, Sizing, Power flow, Noise analysis, Parameter Uncertainty, and Proof of Concept
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The optimal design of the disk of a turbine engine rotor stage is examined as a means of reducing worst-case blade vibration and stress levels. The cross-sectional profile of the disk is modified in search of an optimum that achieves... more
The optimal design of the disk of a turbine engine rotor stage is examined as a means of reducing worst-case blade vibration and stress levels. The cross-sectional profile of the disk is modified in search of an optimum that achieves minimum weight while ensuring that the stresses due to centrifugal loading and vibration remain below a safe level, as defined by a Goodman diagram, even when blade mistuning is introduced. In order to predict the vibration response of a tuned or mistuned bladed disk, a reduced-order modeling technique is employed. Rotational effects are included in the reduced-order model, and a response metric based on vibration energy is used to estimate the dynamic stress level. This process enables the evaluation of a design configuration in a manner that is sufficiently rapid to enable a comprehensive design optimization process. Using two example systems, the developed design methodology is found to yield bladed disk designs that are less sensitive to blade mistuning, thus reducing maximum stress and alleviating high cycle fatigue failure concerns.
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Page 1. REPORT DOCUMENTATION PAGE AFRL-SR-AR-TR-02-Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searchi f\7^J / JI / iw'n9 the... more
Page 1. REPORT DOCUMENTATION PAGE AFRL-SR-AR-TR-02-Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searchi f\7^J / JI / iw'n9 the collection of information. ...
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In this study, the mechanical behavior, joint characterization and process sensitivity of aluminum 6061-T6 alloy Resistance Spot Welded (RSW) joints are investigated. Tensile tests were conducted on single weld lap-shear coupons until... more
In this study, the mechanical behavior, joint characterization and process sensitivity of aluminum 6061-T6 alloy Resistance Spot Welded (RSW) joints are investigated. Tensile tests were conducted on single weld lap-shear coupons until failure in order to determine the optimum welding parameters. Welding currents, forces and times have been investigated to establish the correlation between failure loads and nugget sizes. The experimental and preliminary finite element analysis (FEA) results indicate that failure loads and nugget sizes are strongly dependent upon welding parameters and the material anisotropy.
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The present work is concerned with predicting the power flow between two coupled substructures with parameter uncertainties. The power flow is averaged over an ensemble of systems due to the variation of the system parameters. The... more
The present work is concerned with predicting the power flow between two coupled substructures with parameter uncertainties. The power flow is averaged over an ensemble of systems due to the variation of the system parameters. The ultimate aim is to develop a statistical method which may be applied to the mid-frequency range of vibration for a complex structure. The system considered in this paper is two coupled, nominally identical beams on simple supports, with a torsional spring attached at the coupling point. Various methods are presented to calculate the power flow for this system. The Parameter-based Statistical Energy Method (PSEM) is applied to a classical modal solution and a wave solution. The wave approach appears to be more accurate and computationally efficient for this one-dimensional system. The power flow formulated by applying Component Mode Synthesis (CMS) is also presented. It is seen that the CMS formulation may provide a framework for the efficient numerical ana...
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In this paper we propose a value-iteration based algorithm to compute controlled invariant sets in cases where the range of certain parameters in the system model are not known a priori. By defining the value function in a way that is... more
In this paper we propose a value-iteration based algorithm to compute controlled invariant sets in cases where the range of certain parameters in the system model are not known a priori. By defining the value function in a way that is related to parameter ranges, the proposed computation allows us to analyze parameter sensitivity for the controlled invariant set. The convergence properties of the algorithm are analyzed for certain classes of systems. Finally, a vehicle team power management case study is used to illustrate the efficacy and scalability of the proposed algorithm.
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In this paper, the free response of bladed disks with intentional mistuning is considered in detail. A simple lumped-parameter model of a bladed disk is employed. Intentional mistuning is included by applying a sinusoidal variation to the... more
In this paper, the free response of bladed disks with intentional mistuning is considered in detail. A simple lumped-parameter model of a bladed disk is employed. Intentional mistuning is included by applying a sinusoidal variation to the nominal blade stiffnesses. It is shown that if the intentional mistuning harmonic number and the number of blades have a common integer factor greater than one, then the eigenvalue problem reduces to a set of smaller problems. It is found that the ratio of intentional mistuning strength to the interblade coupling strength is a key parameter for the free response. As this ratio increases, the modes become localized. More importantly, the modes of the intentionally mistuned system have several non-zero nodal diameter components, in contrast to the tuned system which has pure nodal diameter modes. Furthermore, if only random mistuning is present, each mode of the bladed disk assembly still retains a strong nodal diameter component. However, the modes ...
A proposed new method of energy absorption in multilayered plates is to implement shearthickening fluids between the plate layers to act as a damping mechanism. Research into the implementation of shear thickening fluids (STF) in Kevlar... more
A proposed new method of energy absorption in multilayered plates is to implement shearthickening fluids between the plate layers to act as a damping mechanism. Research into the implementation of shear thickening fluids (STF) in Kevlar body armor has yielded positive results for ballistic loadings. The objective of this integrated computational materials engineering (ICME) study is to accurately model the behavior of shear thickening fluids using the discrete element method (DEM) to better understand shear-thickening mechanisms and how shear thickening fluids behave under high shear rates experienced during impulse loading. These results are implemented in a reduced order model of a multilayered plate to determine the effect of shear thickening fluids on energy absorption capabilities. INTRODUCTION Structural energy absorption is critical for improving vehicle survivability and mitigating occupant injury in blast events. Increasing armor material is not always a viable solution; th...
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ABSTRACT Modeling and fast reanalysis techniques are proposed for predicting the dynamic response of complex structures with uncertainty represented by parameter variability (in geometric and material properties) at component-level. The... more
ABSTRACT Modeling and fast reanalysis techniques are proposed for predicting the dynamic response of complex structures with uncertainty represented by parameter variability (in geometric and material properties) at component-level. The novel models allow for accurate reanalyses and are useful in many applications where the model of the pristine structure may not capture the changes in the system-level response due to component-level parameter variations. Herein, such models are obtained by using a novel approach based on a modified concept of component mode synthesis. The novel models, referred to as parametric reduced-order models, are developed for the general case of multiple substructures with parameter variabilities. Three types of parameteric variabilities are considered: (a) geometric (thickness) variability, (b) structural deformations (dents), and (c) cracks. For the first case, a novel parametrization of component-level mass and stiffness matrices is employed to predict the system-level response. For the second case, a novel approximate method based on static mode compensation is implemented. For the third case (cracks), a generalized formulation for the bi-linear frequency approximation is used. The predicted vibration responses of complex structures are shown to agree very well with results obtained using a much more computationally expensive commercial tool.
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This work presents a framework for multi-robot tour guidance in a partially known environment with uncertainty, such as a museum. In the proposed centralized multi-robot planner, a simultaneous matching and routing problem (SMRP) is... more
This work presents a framework for multi-robot tour guidance in a partially known environment with uncertainty, such as a museum. In the proposed centralized multi-robot planner, a simultaneous matching and routing problem (SMRP) is formulated to match the humans with robot guides according to their selected places of interest (POIs) and generate the routes and schedules for the robots according to uncertain spatial and time estimation. A large neighborhood search algorithm is developed to efficiently find sub-optimal low-cost solutions for the SMRP. The scalability and optimality of the multi-robot planner are evaluated computationally under different numbers of humans, robots, and POIs. The largest case tested involves 50 robots, 250 humans, and 50 POIs. Then, a photo-realistic multi-robot simulation platform was developed based on Habitat-AI to verify the tour guiding performance in an uncertain indoor environment. Results demonstrate that the proposed centralized tour planner is...
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One of the main thrusts in current Army Science & Technology (S&T) activities is the development of occupant-centric vehicle structures that make the operation of the vehicle both comfortable and safe for the soldiers. Furthermore, a... more
One of the main thrusts in current Army Science & Technology (S&T) activities is the development of occupant-centric vehicle structures that make the operation of the vehicle both comfortable and safe for the soldiers. Furthermore, a lighter weight vehicle structure is an enabling factor for faster transport, higher mobility, greater fuel conservation, higher payload, and a reduced ground footprint of supporting forces. Therefore, a key design challenge is to develop lightweight occupant-centric vehicle structures that can provide high levels of protection against explosive threats. In this paper, concepts for using materials, damping and other mechanisms to design structures with unique dynamic characteristics for mitigating blast loads are investigated. The Dynamic Response Index (DRI) metric [1] is employed as an occupant injury measure for determining the effectiveness of the each blast mitigation configuration that is considered. A model of the TARDEC Generic V-Hull structure c...
Autonomous robots have significant potential for reconnaissance and environmental monitoring applications. Ground robots, in particular, are performing reconnaissance missions in places that are too hazardous for humans. However, these... more
Autonomous robots have significant potential for reconnaissance and environmental monitoring applications. Ground robots, in particular, are performing reconnaissance missions in places that are too hazardous for humans. However, these robots are constrained by energy limitations that are impacted by uncertain environments and harsh terrains. The purpose of this work is to develop methods for improving the efficiency of reconnaissance missions through energy awareness. To address such limitations, robot energy usage is spatially modeled with a Gaussian Process (GP) through measurements collected during the mission. The resulting energy predictions are incorporated into a centralized waypoint-based optimization with the goal of minimizing the uncertainty of a spatio-temporal field, subject to ensuring the robots' return to their respective starting locations for refueling. Simulation results for a 3-robot system demonstrate the effectiveness of incorporating energy predictions into reconnaissance missions.
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Motivated by military applications, this work considers connected platoons of ground vehicles of potentially different sizes and presents a model-free approach for optimizing the speed of the plato...
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In this paper, Component Mode Synthesis (CMS) is used as a basis for predicting power flow in complex structures. Each component structure may be represented by a separate finite element model. The Craig-Bampton method of CMS is used to... more
In this paper, Component Mode Synthesis (CMS) is used as a basis for predicting power flow in complex structures. Each component structure may be represented by a separate finite element model. The Craig-Bampton method of CMS is used to formulate a reduced order model of ...
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Blade-to-blade mistuning is always inevitable in bladed disk assemblies due to imperfections in the manufacturing progress as well as wear during operation. As a result, the forced response of a mistuned bladed disk may be drastically... more
Blade-to-blade mistuning is always inevitable in bladed disk assemblies due to imperfections in the manufacturing progress as well as wear during operation. As a result, the forced response of a mistuned bladed disk may be drastically larger than that of the nominal or tuned design. The attendant increase in stress can lead to premature high cycle fatigue (HCF) of the blades. Therefore, it is of great importance to predict and, ultimately, to reduce the blade forced response levels caused by mistuning. In this paper, intentional and random mistuning is introduced into a simplified 12-bladed disk model by varying the stiffness of the blades. The combined effects of intentional mistuning, damping and coupling are examined. The numerical results indicate that there is some threshold value of intentional mistuning and coupling that leads to maximum mistuning effects and certain relations among intentional mistuning strength, integer harmonics, damping and coupling can suppress the respo...