Mobile networks, constructed with simple linkages by tessellation, have great application potential in engineering as they could change their shapes according to the need of working state by one degree of freedom (DOF). However, the existing one-DOF networks are always composed of bar-like links, and cooperated membranes should be designed and fabricated additionally, which makes the design and the realization more complicated. This paper is to construct a one-DOF network of Bennett linkages with identical square panels. Geometric conditions to construct the network are derived by investigating the kinematic compatibility, kinematics is carried out to show the relationships among all Bennett linkages, and the discussion on the design parameter shows the extensibility and the deploying performance, which is validated by two physical prototypes. This work initials the construction of mobile networks with identical polygon-like links, which will simplify the fabrication and realization of deployable structures.

The multi-fidelity surrogate (MFS) model is designed to make use of a small amount of expensive but accurate high-fidelity (HF) information and a lot of inaccurate but cheap low-fidelity (LF) information. In this paper, a canonical correlation analysis (CCA)-based MFS model in which the least squares (LS) method is used to determine optimal parameters, named CCA-LS-MFS, is proposed. The CCA-LS-MFS model consists of three stages. The first stage is to construct two transition matrices of HF and LF samples using the CCA method. Then, the discrepancy function between HF and LF models is constructed. In the third stage, parameters are determined by using the LS method. The correlation between HF and LF models, the cost ratio of HF to LF models, and the combination of HF and LF samples are explored. It is observed that the increase of the correlation between HF and LF models can highly improve the performance of the CCA-LS-MFS model. CCA-LS-MFS is capable of providing more robust performance than the other two baseline MFS models, especially when the HF and LF models are highly or weakly correlated, and is promising for being applied into the engineering problems with unclear correlation between HF and LF models. In addition, it has been found that in case of given total budget and HF information, the cost ratio of HF to LF models plays an important role in prediction performance, which requires more research in the future work.

Lightweight lattice structure generation and topology optimization (TO) are common design methodologies. In order to further improve potential structural stiffness of lattice structures, a method combining the multi-topology lattice structure design based on unit-cell library with topology optimization is proposed to optimize the parts. First, a parametric modeling method to rapidly generate a large number of different types of lattice cells is presented. Then, the unit-cell library and its property space are constructed by calculating the effective mechanical properties via a computational homogenization methodology. Third, the template of compromise Decision Support Problem (cDSP) is applied to generate the optimization formulation. The selective filling function of unit cells and geometric parameter computation algorithm are subsequently given to obtain the optimum lightweight lattice structure with uniformly varying densities across the design space. Lastly, for validation purposes, the effectiveness and robustness of the optimized results are analyzed through finite element analysis (FEA) simulation.

The structural synthesis of Baranov trusses is still an open problem, although Baranov trusses are widely used in the design and analysis of mechanisms and robots. This paper proposes a systematic method for the structural synthesis of Baranov trusses. First, the definition review and the graph-form representations of Baranov trusses are proposed. Second, seven propositions on structural characteristics of Baranov trusses are concluded. Then, based on the set of constraint equations and a rigid subchain detection algorithm, a systematic method is presented to synthesize the complete set of Baranov trusses with a specified number of links. Finally, the synthesis results of contracted graphs (including valid and rigid contracted graphs) and topological graphs of Baranov trusses with up to 13 links are provided, and the synthesis methods and results between ours and the ones in the existing literature are compared and discussed in detail.

The optimization of black-box models is a challenging task owing to the lack of analytic gradient information and structural information about the underlying function, and also due often to significant run times. A common approach to tackling such problems is the implementation of Bayesian global optimization techniques. However, these techniques often rely on surrogate modeling strategies that endow the approximation of the underlying expensive function with nonexistent features. Further, these techniques tend to push new queries away from previously queried design points, making it difficult to locate an optimum point that rests near a previous model evaluation. To overcome these issues, we propose a gold rush (GR) policy that relies on purely local information to identify the next best design alternative to query. The method employs a surrogate constructed pointwise, that adds no additional features to the approximation. The result is a policy that performs well in comparison to state of the art Bayesian global optimization methods on several benchmark problems. The policy is also demonstrated on a constrained optimization problem using a penalty method.

Optimization of dynamic systems often requires system simulation. Several important classes of dynamic system models have computationally expensive time derivative functions, resulting in simulations that are significantly slower than real time. This makes design optimization based on these models impractical. An efficient two-loop method, based on surrogate modeling, is presented here for solving dynamic system design problems with computationally expensive derivative functions. A surrogate model is constructed for only the derivative function instead of the simulation response. Simulation is performed based on the computationally inexpensive surrogate derivative function; this strategy preserves the nature of the dynamic system, and improves computational efficiency and accuracy compared to conventional surrogate modeling. The inner-loop optimization problem is solved for a given derivative function surrogate model (DFSM), and the outer loop updates the surrogate model based on optimization results. One unique challenge of this strategy is to ensure surrogate model accuracy in two regions: near the optimal point in the design space, and near the state trajectory in the state space corresponding to the optimal design. The initial evidence of method effectiveness is demonstrated first using two simple design examples, followed by a more detailed wind turbine codesign problem that accounts for aeroelastic effects and simultaneously optimizes physical and control system design. In the last example, a linear state-dependent model is used that requires computationally expensive matrix updates when either state or design variables change. Results indicate an order-of-magnitude reduction in function evaluations when compared to conventional surrogate modeling. The DFSM method is expected to be beneficial only for problems where derivative function evaluation expense, and not large problem dimension, is the primary contributor to solution expense (a restricted but important problem class). The initial studies presented here revealed opportunities for potential further method improvement and deeper investigation.

Matching of orthopedic plates and bony surfaces does not have a high certainty of success because bone anatomy differs among individuals. Considering that surfaces of both orthopedic plates and bones manifest themselves as freeform surfaces and are especially suitable for surface feature-based design, a novel surface feature-based method for designing orthopedic plates is put forward, with detailed steps as follows. First, the bone surface feature (BSF) is established through feature representation of an average bone surface model, obtained based on the investigated samples. Second, the abutted surface of an orthopedic plate is established directly based on the BSF surface to increase matching between the plate and bony surface. The abutted surface feature (ASF) is then established through feature representation of the abutted surface. Third, the hierarchical mapping relationship between BSF and ASF is setup based on the framework of “three-level parameters and two-grade mappings.” The result is that semantic parameters defined on BSF and ASF are separated as an operation interface to make it convenient to edit orthopedic plates according to bone sizes. Finally, the orthopedic plate is generated by thickening the abutted surface, which is generated based on parameters defined on BSF. Taking radius as an example, a group of volar plates suitable for distal radius with different sizes are generated, showing that the proposed method is valid and feasible. Meanwhile, biomechanical stresses of designed volar plates are analyzed with finite element analysis, and the result shows that designed volar plates have good structural strength.

Modular design is an effective approach to shorten lead-time and reduce cost for development of complex products and systems (CoPS). Because the physical details of the product are not available at the conceptual design stage, considerations in the downstream product development phases such as manufacturing and assembly cannot be used for partition of modules at the conceptual design stage. Since design solution at the conceptual design stage can be modeled by functions and relationships among these functions such as function flows including information flows, material flows, and energy flows, a novel approach is introduced in this research for function module partition of CoPS through community detection using weighted and directed complex networks (WDCN). First, the function structure is obtained and mapped into a weighted and directed complex network. Based on the similarity between behaviors of communities in WDCN and behaviors of modules in CoPS, a LinkRank-based community detection approach is employed for function module partition through optimization with simulated annealing. The function module partition for the power mechanism in a large tonnage crawler crane is conducted as a case study to demonstrate the effectiveness of the developed approach.

Different from explicit customer needs that can be identified directly by analyzing raw data from the customers, latent customer needs are often implied in the semantics of use cases underlying customer needs information. Due to difficulties in understanding semantic implications associated with use cases, typical text mining-based methods can hardly identify latent customer needs, as opposite to keywords mining for explicit customer needs. This paper proposes a two-layer model for latent customer needs elicitation through use case reasoning. The first layer emphasizes sentiment analysis, aiming to identify explicit customer needs based on the product attributes and ordinary use cases extracted from online product reviews. Fuzzy support vector machines (SVMs) are developed to build sentiment prediction models based on a list of affective lexicons. The second layer is geared toward use case analogical reasoning, to identify implicit characteristics of latent customer needs by reasoning the semantic similarities and differences analogically between the ordinary and extraordinary use cases. Case-based reasoning (CBR) is utilized to perform case retrieval and case adaptation. A case study of Kindle Fire HD 7 in. tablet is developed to illustrate the potential and feasibility of the proposed method.

A novel structural mechanism (SM) that is capable of transforming itself into various hyperbolic paraboloid (hypar) geometries is introduced in this paper. Composed of straight bars and novel joint types, the SM is designed based on the ruled surface generation method. Thus, the paper first investigates the geometrical properties and morphology of the hypar surface. Second, it constructs the SM and discusses its transformation capability with respect to its kinematic properties. Then, it presents a parametric model not only to analyze the geometry and possible configurations of the SM but also to prepare a model for the structural analysis. Finally, a transformable shelter structure is proposed as an architectural application of the SM and its feasibility is tested based on the structural analysis conducted in different configurations of the structure. According to the results of the structural analysis, the strength, and the stiffness of the structure are discussed in detail.

Past studies have identified the following cognitive skills relevant to conceptual design: divergent thinking, spatial reasoning, visual thinking, abstract reasoning, and problem formulation (PF). Standardized tests are being developed to assess these skills. The tests on divergent thinking and visual thinking are fully developed and validated; this paper focuses on the development of a test of abstract reasoning in the context of engineering design. Similar to the two previous papers, this paper reports on the theoretical and empirical basis for skill identification and test development. Cognitive studies of human problem solving and design thinking revealed four indicators of abstract reasoning: qualitative deductive reasoning (DR), qualitative inductive reasoning (IR), analogical reasoning (AnR), and abductive reasoning (AbR). Each of these is characterized in terms of measurable indicators. The paper presents test construction procedures, trial runs, data collection, norming studies, and test refinement. Initial versions of the test were given to approximately 250 subjects to determine the clarity of the test problems, time allocation and to gauge the difficulty level. A protocol study was also conducted to assess test content validity. The beta version was given to approximately 100 students and the data collected was used for norming studies and test validation. Analysis of test results suggested high internal consistency; factor analysis revealed four eigenvalues above 1.0, indicating assessment of four different subskills by the test (as initially proposed by four indicators). The composite Cronbach’s alpha for all of the factors together was found to be 0.579. Future research will be conducted on criterion validity.

The crochet knitting machine is a warp knitting machine with a weft insertion system placed on a weft guide bar. On standard machines, the weft guide bar is made from aluminum and weighs about 570 g. The single-drive motors, which power the bar, account for 15–20% of the machines total power consumption. The aim of this research was to reduce power consumption by decreasing the mass of the weft guide bar. This was done by constructing the bar from carbon fiber reinforced plastics rather than aluminum, resulting in a mass saving of 260 g.

Geometric constraint programming (GCP) is an approach to synthesizing planar mechanisms in the sketching mode of commercial parametric computer-aided design software by imposing geometric constraints using the software's existing graphical user interface. GCP complements the accuracy of analytical methods with the intuition developed from graphical methods. Its applicability to motion generation, function generation, and path generation for finitely separated positions has been previously reported. By implementing existing, well-known theory, this technical brief demonstrates how GCP can be applied to kinematic synthesis for motion generation involving infinitesimally and multiply separated positions. For these cases, the graphically imposed geometric constraints alone will in general not provide a solution, so the designer must parametrically relate dimensions of entities within the graphical construction to achieve designs that automatically update when a defining parameter is altered. For three infinitesimally separated positions, the designer constructs an acceleration polygon to locate the inflection circle defined by the desired motion state. With the inflection circle in place, the designer can rapidly explore the design space using the graphical second Bobillier construction. For multiply separated position problems in which only two infinitesimally separated positions are considered, the designer constrains the instant center of the mechanism to be in the desired location. For example, four-bar linkages are designed using these techniques with three infinitesimally separated positions and two different combinations of four multiply separated positions. The ease of implementing the techniques may make synthesis for infinitesimally and multiply separated positions more accessible to mechanism designers and undergraduate students.

As an ancient paper craft originating from Japan, origami has been naturally embedded and contextualized in a variety of applications in the fields of mathematics, engineering, food packaging, and biological design. The computational and manufacturing capabilities today urge us to develop significantly new forms of folding as well as different materials for folding. In this paper, by allowing line cuts with crease patterns and creating folded hinges across basic structural units (BSU), typically not done in origami, we achieve a new multiprimitive folding framework such as using tetrahedral, cuboidal, prismatic, and pyramidal components, called “Kinetogami.” “Kinetogami” enables one to fold up closed-loop(s) polyhedral mechanisms (linkages) with multi-degree-of-freedom and self-deployable characteristics in a single build. This paper discusses a set of mathematical and design theories to enable design of 3D structures and mechanisms all folded from preplanned printed sheet materials. We present prototypical exploration of folding polyhedral mechanisms in a hierarchical manner as well as their transformations through reconfiguration that reorients the material and structure. The explicit 2D fabrication layout and construction rules are visually parameterized for geometric properties to ensure a continuous folding motion free of intersection. As a demonstration artifact, a multimaterial sheet is 3D printed with elastomeric flexure hinges connecting the rigid plastic facets.

This paper discusses the gear coupling mechanics of the ancient Antikythera mechanism, among whose distinctive characteristics was the triangular shaping of the teeth. The engagement of the tooth pairs is analyzed in detail, estimating the temporal variation of the speed ratio due to the back and forth shifting of the relative instant center. The admissibility of the theoretical contact points is carefully checked, and the magnitude of the successive tooth collisions is calculated together with the energy losses arising from the particular nature of the coupling. Some interesting results are that only one tooth pair turns out to be active at each time instant and the real path may belong only to the approach or to the recess region entirely, or may split into separate subphases, in approach and in recess, or may even straddle both regions. The occurrence of each of these conditions depends on the average speed ratio (tooth ratio) and the assigned clearance between the wheels. It is also found that the speed oscillation is roughly contained in a ±10% range and the efficiency may reach rather high values, despite the presumable crude finishing of the ancient gearwheels due to the rather rudimentary technology used in the construction of the tooth profiles.

An attempt has been made in this work to develop a simple yet efficient sun tracking mechanism (SSTM) using smart shape memory alloy (SMA). This mechanism is directly activated by the sun dispensing with the requirement of an additional external source to power it. The SMA element incorporated in the SSTM device performs the dual functions of sensing and actuating in such a way as to position the solar receptor tilted appropriately to face the sun directly at all times during the day. The mechanism has been designed such that the thermal stimulus needed to activate the SMA element is provided by the concentration and direct focusing of the incident sun rays on to the SMA element. This paper presents, in detail, the design and construction adopted to develop the functional model that was fabricated and tested for performance.

This paper proposes a new synthesis approach by using constraints for limb synthesis to target mobility-change in the mechanism construction. The limbs therefore produced have the facility to reconfigure the limb twist-system to change the screw system order for reconfigurability. This presents various reconfigurable limbs with geometric constraints of their joints based on the newly invented reconfigurable Hook (rT) joints. The procedure of the limb synthesis is put forward to fully utilize the property of the new joint for generating the reconfigurable limbs. The paper further presents a mobility-change condition to construct a metamorphic mechanism with the reconfigurable limbs. This gives a family of metamorphic parallel mechanisms that have the facility to change mobility in the range of 3– 6. A further family of metamorphic parallel mechanisms is proposed with a central strut. Their topological configuration change is investigated by examining the constraint change stemming from the phase alteration of the reconfigurable Hooke rT joint.

Computational tools such as finite element analysis and simulation are widely used in engineering, but they are mostly used for design analysis and validation. If these tools can be integrated for design optimization, it will undoubtedly enhance a manufacturer’s competitiveness. Such integration, however, faces three main challenges: (1) high computational expense of simulation, (2) the simulation process being a black-box function, and (3) design problems being high dimensional. In the past two decades, metamodeling has been intensively developed to deal with expensive black-box functions, and has achieved success for low dimensional design problems. But when high dimensionality is also present in design, which is often found in practice, there lacks of a practical method to deal with the so-called high dimensional, expensive, and black-box (HEB) problems. This paper proposes the first metamodel of its kind to tackle the HEB problem. This paper integrates the radial basis function with high dimensional model representation into a new model, RBF-HDMR. The developed RBF-HDMR model offers an explicit function expression, and can reveal (1) the contribution of each design variable, (2) inherent linearity/nonlinearity with respect to input variables, and (3) correlation relationships among input variables. An accompanying algorithm to construct the RBF-HDMR has also been developed. The model and the algorithm fundamentally change the exponentially growing computation cost to be polynomial. Testing and comparison confirm the efficiency and capability of RBF-HDMR for HEB problems.

Gear dynamic models with time-varying mesh stiffness, viscous mesh damping, and sliding friction forces and moments lead to complex periodic differential equations. For example, the multiplicative effect generates higher mesh harmonics. In prior studies, time-domain integration and fast Fourier transform analysis have been utilized, but these methods are computationally sensitive. Therefore, semianalytical single- and multiterm harmonic balance methods are developed for an efficient construction of the frequency responses. First, an analytical single-degree-of-freedom, linear time-varying system model is developed for a spur gear pair in terms of the dynamic transmission error. Harmonic solutions are then derived and validated by comparing with numerical integration results. Next, harmonic solutions are extended to a six-degree-of-freedom system model for the prediction of (normal) mesh loads, friction forces, and pinion/gear displacements (in both line-of-action and off-line-of-action directions). Semianalytical predictions compare well with numerical simulations under nonresonant conditions and provide insights into the interaction between sliding friction and mesh stiffness.

This paper proposes a synthesis method for rectilinear motion generating spatial mechanism with application to automotive suspension. First, it presents a generic process to synthesize the kinematic chains of a mechanism with the prescribed mobility, and then it deduces the construction criteria of feasible kinematic chains for such a mechanism. The most outstanding advantages of the rectilinear motion generating spatial mechanism used as the independent automotive suspension are that the orientation and position parameters such as kingpin, caster, camber, axis distance, and wheel track are always maintained constant during jounce and rebound. These ideal characteristics are guaranteed by the particular rigid guidance mechanism whose end effector only has one translation along an exact straight line.