Georges Fadel

Clemson University | CU · Department of Mechanical Engineering

This paper presents approaches to compare criteria and help designers make decisions based on trade-offs between criteria. The impetus for the paper is to identify possible directions to improve/innovate a product and propose a value shell model displaying various criteria or their combination to represent the effort needed to improve the criteria....

Planning the shortest collision-free path among scattered obstacles is an NP-complete problem. As reviewed in this paper, a variety of deterministic as well as heuristic methods have been developed to address different instances of the problem. The focus of the deterministic methods is primarily on the optimality of the final solution. Nevertheless...

Advances in machine learning algorithms and increased computational efficiencies give engineers new capabilities and tools to apply to engineering design. Machine learning models can approximate complex functions and, therefore, can be useful for various tasks in the engineering design workflow. This paper investigates using reinforcement learning...

Affordance-based design (ABD) plays an important role in identifying interactions, especially effortless ones, between users and artifacts. Cognitive ergonomics extends our understanding of this effortless interaction. This study combines the two design methodologies together in order to reduce cognitive friction in using digital products. The desi...

Structures with adaptive capabilities offer many potentials to achieve future needs in efficiency, reliability, and intelligence. To this end, bistable CFRP (Carbon Fibre Reinforced Polymers) composites with asymmetric fiber layout are a promising concept that has shown shape morphing capabilities that adapt to the changes in the environment such a...

Thin bistable composite laminates can be used for shape morphing applications by virtue of their material properties and asymmetric ply layup. These laminates are called bistable because they can be snapped into two or more stable shapes. A single bistable patch can result in simple cylindrical shapes and when multiple such patches are assembled in...

This paper is an invitation to a debate on the positioning of engineering design as a field of research. The paper lists a multiplicity of interpretations of design, questioning whether they are sufficient to describe engineering design in all its variety. Following a critical analysis of attempts to describe design's unique characteristics, and ob...

The components of complex systems such as automobiles or ships communicate via connectors, including wires, hoses, or pipes whose weight could substantially increase the total weight of the system. Hence, it is of paramount importance to lay out these connectors such that their overall weight is minimized. In this paper, a computationally efficient...

Bistable carbon fiber composites, whose bistability arises from having asymmetric fiber layouts in different layers, have shown immense potential for using in shape morphing and adaptive structure applications. While many studies in this field focus on these composite laminates’ external shapes at the two stable states, their snap-through behavior...

While using a prosthesis, transtibial amputees can experience pain and discomfort brought on by large pressure gradients at the interface between the residual limb and prosthetic socket. Current prosthetic interface solutions attempt to alleviate these pressure gradients by using soft homogenous liners to reduce and distribute pressures. This resea...

Hysteretic energy loss occurs in bistable curved beams when they undergo back-and-forth snap-throughs due to cyclic loading. While numerical models and simulations can be employed to calculate the energy loss for a given curve beam or system, the effect of design parameters of the beams on the energy loss behavior remains largely implicit in the ca...

This paper presents recent advances in developing a systematic design procedure for nonlinear cellular meta-materials. In previous work by the authors, the Unit Cell Synthesis method was introduced for designing unit-cell-based meta-materials that exhibit targeted nonlinear deformation response. The method is based on a fundamental understanding of...

While using a prosthesis, transtibial amputees can experience pain and discomfort brought on by large pressure gradients, at the interface between the residual limb and prosthetic socket. Current prosthetic interface solutions attempt to alleviate these pressure gradients by using soft homogenous liners to reduce and distribute pressures. This rese...

Ultrasonic vibration has been observed to lower the flow stress necessary to initiate plastic deformation, a phenomenon known as "acoustic softening". This unique effect of ultrasound has been extensively applied in welding, machining, forming of metals, and ultrasonic additive manufacturing to lower the yield stress necessary to initiate plastic d...

The identification, selection, and consideration of appropriate affordances during the preliminary design phase of a product play a critical role in the process of Affordance Based Design (ABD). A design tool named Affordance Based Interactive Genetic Algorithm (ABIGA) evolves products by having designers identify, and then users assess the afforda...

Meta-materials are a class of artificial materials with a wide range of bulk properties that are different from the base material they are made of. The term meta-material in the context of this research refers to a continuous, heterogeneous structure with prescribed elastic properties. Such meta-materials are designed using Topology Optimization (T...

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...

Parametric Optimization is used to solve problems that have certain design variables as implicit functions of some independent input parameters. The optimal solutions and optimal objective function values are provided as functions of the input parameters for the entire parameter space of interest. Since exact solutions are available merely for para...

Maier and Fadel pioneered Affordance-Based Design (ABD) based on Gibson's revolutionary theory of affordances and Norman's deployment of the concept in his book, “The Design of Everyday Things”. Gibson (1979) introduced the affordance concept into the discipline of Ecological Psychology to address the interactions between an object and an agent. Th...

Routing or path-planning is the problem of finding a collision-free and preferably shortest path in an environment usually scattered with polygonal or polyhedral obstacles. The geometric algorithms oftentimes tackle the problem by modeling the environment as a collision-free graph. Search algorithms such as Dijkstra’s can then be applied to find an...

The design process of laminated composites faces two challenges: the engineer designs the product and its morphology, but also, simultaneously, the material. The number of design solutions can be huge since the solution space is very large. Standard CAE systems (CAD, Finite Element Simulation) do not offer to the designer an approach to explore des...

The design process of laminated composites faces two challenges: the engineer designs the product and its morphology, but also, simultaneously, the material. The number of design solutions can be huge since the solution space is very large. Standard CAE systems (CAD, Finite Element Simulation) do not offer to the designer an approach to explore the...

Purpose For part models with complex shape features or freeform shapes, the existing build orientation determination methods may have issues, such as difficulty in defining features and costly computation. To deal with these issues, this paper aims to introduce a new statistical method to develop fast automatic decision support tools for additive m...

The goal of this research is to optimize an object's macroscopic topology and localized gradient material properties (GMPs) subject to multiple loading conditions simultaneously. The gradient material of each macroscopic cell is modeled as an orthotropic material where the elastic moduli in two local orthogonal directions we call x and y can change...

Build orientation determination is one of the most important preprocessing steps in Additive Manufacturing (AM) since the build orientation affects the manufacturing quality, time and cost of building a part. For part models with regular shapes features, there is already a plethora of orientation optimization methods proposed in the literature. How...

The problem of finding a collision free path in an environment occupied by obstacles, known as path planning, has many applications in design of complex systems such as wire routing in automobile assemblies or motion planning for robots. Developing the visibility graph of the workspace is among the first techniques to address the path-planning prob...

Designers can involve users in the design process. The challenge lies in reaching multiple users and finding the best way to use their input in the design process. Affordance based design (ABD) is a design method that focuses in part on the perceived or existing interactions between the user and the artifact. The shape and physical characteristics...

This report introduces a novel, generic, multi-layered network model of large-scale multicriteria decision making (MCDM), with a focus on the design and optimization of complex products and platforms. The report provides some examples of network structures in MCDM applications and develops two use-cases for the multi-layered model. The starting poi...

During the past few years, the need for functionally graded material (FGM) parts has surfaced with the development of material science and additive manufacturing techniques. The Direct Metal Depo-sition (DMD) process, a metal based additive manufacturing technique, can locally deposit dissimilar metal powders to produce FGM parts. Yet inappropriate...

A systematic unit cell synthesis approach is presented for designing metamaterials from a unit cell level, which are made out of linearly elastic constitutive materials to achieve tunable nonlinear deformation characteristics. This method is expected to serve as an alternative to classical Topology Optimization methods (solid isotropic material wit...

Affordance based design is developed since the beginning of 21 st century. Affordances being revealed properties of a system in a context, they may be much diverse and unexpected. Consequently, it is an utopia to think of enumerating all the existing precise affordances in advance. Presently, identifying affordances along a design or redesign proce...

The goal of this research is to optimize an object’s macroscopic topology and gradient material properties subject to multiple loading conditions. The gradient material is modeled as an orthotropic material where the elastic modulus in the x and y directions can change in addition to rotating the orthotropic material to align with the loading condi...

Purpose This paper aims to introduce a new nesting scheme to better describe and solve the single-layer-part packing problem in additive manufacturing (AM). Design/methodology/approach Parallel nesting scheme using two-dimensional (2D) changeable projection profiles is developed. At first, a feature-based orientation optimization method is used to...

The direct metal deposition (DMD) process is one of the metal-based additive manufacturing techniques available today. In this study, an injection nozzle design methodology is proposed based on the finite element modeling of substrate temperature and powder distribution. The design methodology is applied to the deposition of Ti-6Al-4V powder in bui...

During the past few years, metal-based additive manufacturing technologies have evolved and may enable the direct fabrication of heterogeneous objects with full spatial material variations. A heterogeneous object has potentially many advantages, and in many cases can realize the appearance and/or functionality that homogeneous objects cannot achiev...

The augmented Lagrangian coordination (ALC), as an effective coordination method for decomposition-based optimization, offers significant flexibility by providing different variants when solving nonhierarchically decomposed problems. In this paper, these ALC variants are analyzed with respect to the number of levels and multipliers, and the resulti...

The objective of this research is to optimally design both the topology and material distribution of functionally gradient material objects while considering more than one objective. Many techniques exist for both topology optimization and optimal placement of functionally gradient material within a single object, but combining the two is challengi...

The need for functionally graded material (FGM) parts has surfaced with the development of material science and additive manufacturing techniques. Direct Metal Deposition (DMD) processes can locally deposit different metallic powders to produce FGM parts. Yet inappropriate mixing of materials without considering the influence of varying dilution ra...

The Direct Metal Deposition (DMD) process is one of the most important metal based additive manufacturing techniques available today. In this study, a print head design optimization methodology is proposed based on the finite element modeling of powder distribution and substrate temperature distribution. The design methodology is applied to the dep...

In this chapter, the authors summarize many years of design research at Clemson University and the subsequent impact on industrial practice, particularly in the evolution and transition of disparate ideas into cohesive concepts that were eventually transitioned to industry. In design research, a broad area of endeavor, design theories take the long...

The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major op...

The cooling system for internal combustion engines removes waste heat to ensure a normal in-cylinder combustion process. To accomplish this task, the thermostat valve, radiator, radiator fan(s), and water pump circulate cooling fluid through the engine block and reject heat to the local environment. Since the cooling system consumes a portion of th...

Over the past decade, there has been an increase in the intentional design of meso-structured materials that are optimized to target desired material properties. This paper reviews and critically compares common numerical methodologies and optimization techniques used to design these meso-structures by analyzing the methods themselves and published...

During the past few years, metal based additive manufacturing technologies have evolved and may enable the direct fabrication of heterogeneous objects with full spatial material variations. A heterogeneous object has potentially many advantages and in many cases can realize appearance and/or functionality that homogeneous objects cannot achieve. In...

This paper presents the challenges and solutions encountered while printing functionally gradient material (FGM) objects using an off the shelf Fused Deposition Modeling (FDM) 3D printer. The printer, Build Builder Dual-Feed Extruder from 3dprinter4u, has the unique design of extruding two different filaments out of one nozzle. Two separate motors...

Augmented Lagrangian Coordination (ALC) is one of the more popular coordination strategies for decomposition based optimization. It employs the augmented Lagrangian relaxation approach and has shown great improvements in terms of efficiency and solution accuracy when compared to other methods addressing the same type of problem. Additionally, by of...

The objective of this research is to develop a computational representation of knowledge associated with affordance-based design (ABD). The ABD ontology formalizes the entities, properties, and relationships within the domains of ABD. The ontology enables designers to describe the affordances of existing products and specify the intended affordance...

In industrial design, color is one of the most expressive and appealing attributes of an artifact. Specifically, color can induce feelings (color attractiveness) and or the perception of some affordances (“color affordance”) in users. Researchers define “color affordance” as the inducing of a certain behavior, perception or understandings in direct...

This paper presents the challenges and solutions encountered while designing and then printing functionally gradient material (FGM) objects using an off the shelf fused deposition modeling (FDM) 3D printer. The printer, Big Builder Dual-Feed Extruder from 3dprinter4u, Noordwijkerhout, The Netherlands, has the unique design of extruding two differen...

Centralized augmented Lagrangian coordination (ALC) has drawn much attention due to its parallel computation capability, efficiency, and flexibility. The initial setting and update strategy of the penalty weights in this method are critical to its performance. The traditional weight update strategy always increases the weights and research shows th...

Systematic engineering of components that employ metamaterials has expanded the mechanical design field in recent years. Yet, topology optimization remains a burdensome tool to utilize within a systematic engineering paradigm. In this work, the design of a metamaterial shear beam for a nonpneumatic wheel using a systematic, two-level design approac...

Packing for engineering design involves the development and use of methods to determine the arrangement of a set of subsystems or components within some enclosure to achieve a set of objectives without violating spatial or performance constraints. Packing problems, also known as layout optimization problems are challenging because they are highly m...

The successful application of multiobjective optimization to engineering problems has motivated studies of more complex systems involving multiple subsystems and design disciplines, each with multiple design criteria. Complex system design requires participation of different teams that are highly specialized within each discipline and subsystem. Su...

Blaha and Langenecker are the first to document the phenomena known as "acoustic softening": a significant reduction of static stress in tensile tests when applying longitudinal ultrasonic waves to various metals. Based on experimental observations, they hypothesized that acoustic heating due to internal friction and energy activation at dislocatio...

Functionally Gradient Materials (FGM) smoothly transition from one material to another within a single object, allowing engineers to customize the physical response of different regions of the object by modifying the material composition at each region. New FGM research makes design, manufacturing, and use of FGM objects a promising alternative to...

As system design problems increase in complexity, researchers seek approaches to optimize such problems by coordinating the optimizations of decomposed sub-problems. Many methods for optimization by decomposition have been proposed in the literature among which, the Augmented Lagrangian Coordination (ALC) method has drawn much attention due to its...

The complexity of design and optimization tasks of modern products which cannot be carried out by a single expert or by a single design team motivated the development of the field of decomposition-based optimization. In general, the process of decomposition-based optimization consists of two procedures: (1) Partitioning the original problem into su...

In this paper, an algorithm and associated procedure for computing the envelope of non-convex manifold objects is proposed. The envelope generation algorithm is developed in the context of vehicle packaging and layout and is intended for use during the conceptual phase of the vehicle design process. The envelope generation algorithm presented in th...

In this paper, a fast and efficient shape morphing algorithm specifically designed for packing and layout applications is presented. The shape morphing algorithm is based on a modified mass-spring system which is used to model the morphable object. The shape morphing algorithm mimics a quasi-physical process similar to inflation/deflation of a ball...

The present invention provides an improved shear band for use in non-pneumatic tires, pneumatic tires, and other tech nologies. The improved shearband is uniquely constructed of honeycomb shaped units that can replace the elastomeric continuum materials such as natural or synthetic rubber or polyurethane that are typically used. In particular, hone...

A shear layer for a shear band that is used in a tire is provided that has multiple cells or units having an auxetic configuration and that are constructed from aluminum or titanium alloys. The cells may have an angle of −10°

Ultrasonic Additive Manufacturing (UAM) is a promising additive manufacturing process used to build complex structures by joining thin metal films. Layers of metal foil are joined by being compressed under moderate pressure using a rolling ultrasonic horn which vibrates at a high frequency in a direction transverse to the rolling motion. Foil–foil...

The automotive industry is an example of flow production and manufacturing efficiency. Its performance is based on taking the right decisions on strategic, tactical, and operational processes by the responsible engineers. Over the last decade, discrete-event simulation became the tool of choice to verify strategic decisions and tactical measures in...

This paper describes the development and evolution of research themes in the Design Theory and Methodology (DTM) conference. Essays containing reflections on the history of DTM, supported by an analysis of session titles and papers winning the “best paper award”, describe the development of the research themes. A second set of essays describes the...

The increasing computational power available to practitioners leads to challenging applications of optimization approaches to large scale systems. To address such problems, decomposition of the original or “all-in-one” (AiO) problem into smaller and simpler subproblems is the approach taken by engineers. Analytical target cascading (ATC), a hierarc...

This work considers the impact of thermal behavior in battery design. The cell performance worsens when the operating temperature falls outside of the ideal range, and evenness of cell temperatures is sought to prevent cell electrical unbalance which may lead to performance fading and premature failure. The heat transfer between the cells and the c...

Heterogeneous objects have shown their high potential in many areas. Appliances, machines, and parts can be seen as a mixture of materials in a continuous or discrete way. The material distribution affects the properties of the objects, so the combination and the density presence of the materials can be designed to achieve high performance of parts...

Affordance based design (ABD) theory has been presented in several papers and has interested several researchers in the field of design. One criticism of ABD is that the number of affordances identified can be very large, and therefore, the approach may not be amenable for automation. This paper presents a computer based implementation of a process...

The complexity of managing multidisciplinary engineering systems offers an unprecedented opportunity to investigate decomposition methods, which separate a system into a number of smaller subsystems that can be designed in multiple physical locations and coordinate the design of the subsystems to collaboratively achieve the original system design....