An adaptive Dendrite-HDMR metamodeling technique for high dimensional problems

High dimensional model representation (HDMR), decomposing the high-dimensional problem into summands of different order component terms, has been widely researched to work out the dilemma of “curse-of-dimensionality” when using surrogate techniques to approximate high-dimensional problems in engineering design. However, the available one-metamodel-based HDMRs usually encounter the predicament of prediction uncertainty, while current multi-metamodels-based HDMRs cannot provide simple explicit expressions for black-box problems, and have high computational complexity in terms of constructing the model by the explored points and predicting the responses of unobserved locations. Therefore, aimed at such problems, a new stand-alone HDMR metamodeling technique, termed as Dendrite-HDMR, is proposed in this study based on the hierarchical Cut-HDMR and the white-box machine learning algorithm, Dendrite Net. The proposed Dendrite-HDMR not only provides succinct and explicit expressions in the form of Taylor expansion, but also has relatively higher accuracy and stronger stability for most mathematical functions than other classical HDMRs with the assistance of the proposed adaptive sampling strategy, named KKMC, in which k-means clustering algorithm, k-Nearest Neighbor classification algorithm and the maximum curvature information of the provided expression are utilized to sample new points to refine the model. Finally, the Dendrite-HDMR technique is applied to solve the design optimization problem of the solid launch vehicle propulsion system with the purpose of improving the impulse-weight ratio, which represents the design level of the propulsion system.

A Novel Approach to Configuration Redesign: Using Multiobjective Monotonicity Analysis to Alter the Pareto-set

Configuration (or topology or embodiment) design remains a ubiquitous challenge in product design optimization and in design automation, meaning configuration design is largely driven by experience in industrial practice. In this article, we introduce a novel configuration redesign process founded on the interaction of the designer with results from rigorous multiobjective monotonicity analysis. Guided by Pareto-set dependencies, the designer seeks to reduce trade-offs among objectives or improve optimality overall, deriving redesigns that eliminate dependencies or relax active constraints. The method is demonstrated on an ingestible medical device for oral drug delivery, currently in early concept development.

2021 Reviewers With Distinction Award

The Journal of Mechanical Design Reviewers with Distinction Award is given to reviewers who have made a meritorious contribution to the journal in terms of the number, quality, and turnaround time of reviews completed during the past year.

Configuration design and screening of multi-mode double-planetary-gears hybrid powertrains

Hybrid powertrains with planetary gearset(PG) have been widely used. However, there are few types of powertrains in use, more powertrains have not been found. Based on the principle of organic chemistry, a design and screening method of multi-mode 2-PGs hybrid powertrain is proposed, which is divided into five stages. Firstly, powertrains are expressed in the form of molecules. Secondly, powertrains split into the libraries of PGs and power sources. The power sources can be mutually identified to construct new library. Thirdly, the mode switching rules are defined to screen power source group. Fourthly, two libraries interact with each other to promote the generation of new molecules, namely, new powertrains. And the more modes, the greater the vehicle performance potential. Powertrains are screened with mode richness theory firstly. Finally, taking the comprehensive evaluation of power performance and fuel economy as the optimal standard, powertrains are screened and evaluated twice. Through the method, hybrid powertrains with smooth mode switching, simpler structure, and optimal power and economy can be obtained.

A Large Range Compliant Nano-Manipulator Supporting Electron Beam Lithography

Electron beam lithography (EBL) is an important lithographic process of scanning a focused electron beam (e-beam) to direct write a custom pattern with nanometric accuracy. Due to the very limited field of the focused election beam, a motion stage is needed to move the sample to the e-beam field for processing large patterns. In order to eliminate the stitching error induced by the existing “step and scan” process, we in this paper propose a large range compliant nano-manipulator so that the manipulator and the election beam can be moved in a simultaneous manner. We also present an optimization design for the geometric parameters of the compliant manipulator under the vacuum environment. Experimental results demonstrate 1 mm × 1 mm travel range with high linearity, ~ 0.5% cross-axis error and 5 nm resolution. Moreover, the high natural frequency (~ 56 Hz) of the manipulator facilitates it to achieve high-precision motion of EBL.

Deep generative tread pattern design framework for efficient conceptual design

Tire tread patterns have played an important role in the automotive industry because they directly affect automobile performances. The conventional tread pattern development process has successfully produced and manufactured many tire tread patterns. However, a conceptual design process, which is a major part of the whole process, is still time-consuming due to repetitive manual interaction works between designers and engineers. In the worst case, the whole design process must be performed again from the beginning to obtain the required results. In this study, a deep generative tread pattern design framework is proposed to automatically generate various tread patterns satisfying the target tire performances in the conceptual design process. The main concept of the proposed method is that desired tread patterns are obtained through optimization based on integrated functions, which combine generative models and tire performance evaluation functions. To strengthen the effectiveness of the proposed framework, suitable image pre-processing, generative adversarial networks (GANs), 2D image-based tire performance evaluation functions, design generation, design exploration, and image post-processing methods are proposed with the help of domain knowledge of the tread pattern. The numerical results show that the proposed automatic design framework successfully creates various tread patterns satisfying the target tire performances such as summer, winter, or all-season patterns.

An Articulated Robotic Forceps Design with a Parallel Wrist-Gripper Mechanism and Parasitic Motion Compensation

In this paper, a novel 4 degrees-of-freedom articulated parallel forceps mechanism with a large orientation workspace (±/−90deg in pitch and yaw, 360deg in roll rotations) is presented for robotic minimally invasive surgery. The proposed 3RSR-1UUP parallel mechanism utilizes a UUP center-leg which can convert thrust motion of the 3RSR mechanism into gripping motion. This design eliminates the need for an additional gripper actuator, but also introduces the problem of unintentional gripper opening/closing due to parasitic motion of the 3RSR mechanism. Here, position kinematics of the proposed mechanism, including the workspace, is analyzed in detail, and a solution to the parasitic motion problem is provided. Human in the loop simulations with a haptic interface are also performed to confirm the feasibility of the proposed design.

Grooved cam mechanism with a translating follower having an added ternary-roller intermediate link

The paper presents an analytical approach for designing grooved cam mechanisms with a modified arrangement of the common translating follower. That is, an intermediate link having three rollers is added between the cam and the common follower. On the basis of an existing cam mechanism with a common roller follower, an intermediate link that has three rollers is added between the cam and the common follower. Such a cam mechanism has two set of profile and can create multiple contact points between the cam and the follower at any instant. The two sets of profiles of such a cam mechanism can serve as the grooved types. Since the follower has three rollers that can simultaneously contact the cam at any instant, it can be positive driven along the guided groove of cam contour. The contact forces and contact stresses of such cam mechanisms are analyzed to illustrate the advantage of spreading force transmission and reducing contact stress of this uncommon follower. The obtained results indicate that the contact stress at the surface of the cam and the follower for such a cam mechanism can be reduced by 30% to 47% in comparison to those of cam mechanism with a common translating roller follower. In conclusion, the cam mechanism with a translating follower having an added ternary-roller intermediate link can be a preferable choice for the applications that follower is against heavy loads or move at high speed.

Assessing Early Stage Design Sketches and Reflections on Prototyping

Designers routinely create informal “thinking” sketches to explore a design space, “talking” sketches to communicate design ideas during the early phases of the design process, and “learning” prototypes to test potential concepts. This study presents two new tools to assess novice designers' sketch attributes and prototyping reflections in the context of an introductory design course. First, it proposes a rubric for assessing the quality of early stage design sketches including line smoothness, proportion, and understandability. Of particular note is the contribution of assessing understandability as a metric for sketches as communication tools. This study also presents a tool to capture designer reflections after each iteration of a prototype. Not only does this record what is learned about a design, but also personal and emotional reactions to the process. Sketching-related results show a positive correlation between sketch quality and understandability, indicating the importance of sketch quality especially when designers use sketches to communicate. Results also indicate that early stage sketch quantity, but not quality, is linked with design outcomes. The study also finds a link between frequency of sketching and higher maximum sketch quality scores (i.e. at least one excellent sketch) as well as a correlation between individuals' maximum sketch quality scores and overall design outcomes. Preliminary results around prototyping indicate that reflection on both the technical and emotional aspects of prototyping may be a worthwhile area of further study. Finally, several results point to novice designers' lack of consistent focus on users in their prototyping reflections and presentations.

The application of ethnographic methods to engineering for global development: the case of the Improvised Betel Nut Cutter

This technical brief is an attempt to report a case analysis of Engineering for Global Development (EGD) research from India. As a part of the engineering design and research project, two models of Improvised Betel Nut Cutter (IBNC) are designed, manufactured and field-tested. Engineering ethnography is adopted as a research tool during the design process of IBCN. It facilitated the participation of local stakeholders in the design process which is found to be effective for contextual understandings of the target community's needs, aspirations, constraints and socio-cultural norms and values. The technological intervention is expected to solve the problems like finger cuts, health drudgery (musculoskeletal pain, back pain, etc.) of the women involved in the supari business in Assam, India. It will also improve productivity and efficiency in the supari cutting practices of women. This case analysis depicts the effectiveness of trans-disciplinary effort in solving complex engineering problems at the bottom of the pyramid (BOP). Evidence gathered from this study is expected to be a useful resource for future endeavours in EGD research.