This paper considers systems with field constraints, when elements cannot be placed in special regions such as a high-temperature field, a high-pressure field, a high magnetic field, etc.  Fields place constraints on architectural modularity choices and provide creative opportunities for the design of complex systems. This paper develops practical design guidelines for modularity by considering field constraints and highlighting on a system block diagram which elements are within a high field region. The ideas are demonstrated on a medical contrast injector that must partially operate in magnetic and sterile fields. These field constraints are shown to be designer choices: by changing the design concept one can move functional elements into or out of fields. This approach provides opportunities for innovation through a focus on moving field boundaries to generate new product-system architecture concepts. For the medical contrast injector device, an exemplar innovation for higher accuracy dosage was moving the pump away from the motor into the magnetic field through an umbilical drive. Overall, field boundaries are inherent considerations in product architecture, and the techniques in this paper provide a foundational set of guidelines and a general approach for designing systems within such considerations. ​

For the full article visit ASME's Digital Collection

Many modern products, such as automobiles, aircrafts, laptops and smartphones, are engineered systems. The performance, function, and architecture of an engineered system continuously changes and improves over time. For example, cell phones of the 1990’s were limited to phone calls and text messages. Today's cell phones are computers capable of cinematography and reading the news. Research in engineered system evolution goes beyond tracking and predicting the technical performance and the functional and architectural changes of existing engineered systems. This research also studies how and why these changes occur and searches for causal factors behind these evolutions. The results of this research are valuable for designers, R&D managers, investors, and policy makers by aiding the generation of innovative design concepts, setting reasonable R&D targets, investing in promising technologies, and developing effective incentive policies. This paper summarizes key research questions, identifies pioneering literature, and discusses the opportunities and challenges for future research in engineered system evolution. Importantly, a free access database is provided for facilitating future research in this area. The database currently includes more than 100,000 data points that belong to 31 technical performance metric categories of 7 engineering systems (i.e., passenger aircraft, orbital launch system, automobile, computer, refrigerator, lamp, and direct-fire ground weapon systems) and their components.  

Carlye A. Lauff; Daria Kotys-Schwartz; Mark E. Rentschler
J. Mech. Des. 2018; 140(6):061102-061102-12; doi: 10.1115/1.4039340
 
Prototyping is an essential part of a company’s product development process. It is critical to launching new products to market; these products can range from the next generation iPhone to surgical devices for doctors to your favorite shoes. Currently, there are limited research studies conducted within companies, meaning we lack an understanding about how companies engage in prototyping activities. This research project observed the entire product development process within three companies in the fields of consumer electronics, medical devices, and footwear. Through our analysis, we uncovered that prototypes are tools for enhanced communication, increased learning, and informed decision-making.

​Delivering a variety of products with minimal lead time is a critical issue given today’s competitive manufacturing industry. Many design and production firms address the challenges of variety by adopting a product family manufacturing strategy. Product families are a broad range of artifacts, known as product variants, which share a number of common components. Thus, engineering changes in a product family affect the product under consideration and other product variants in the family. This increases the difficulty of predicting the change propagation within a family of products. This paper introduces a seven-step change propagation approach that predicts and evaluates the impact of change propagation across product variants. Interdependencies and logical relationships between directly connected components are captured using a Component-based Design Structure Matrix. This highlights the different change propagation paths that are available in the product’s structure. Risk analysis in terms of lead time is performed at the component level. The results demonstrate that avoiding project delays requires selecting suitable change propagation paths in a family of products.

Jan Andrysek; Matthew J. Leineweber; Hankyu Lee
​J. Mech. Des. 2017; 139(3):035001-035001-7
doi: 10.1115/1.4035372

People with severe impairment of the lower body caused by conditions such as polio or stroke often rely on assistive devices for mobility. Knee orthosis plays an important role in restoring mobility by stabilizing the weakened lower limb and providing support for standing and walking. Concurrently, the orthosis should allow for natural and efficient movement of the limb as required for walking. The focus of this work is to develop a new method for controlling orthotic knee joints. The new control method uses a mechanical system to monitor loading and timing events and patterns, and apply knee-locking function when the limb is loaded. A prototype was built and tested on a polio patient and demonstrated the feasibility of this approach for providing reliable orthotic function. Further work aims to test the knee joint on a larger group of individuals within the community.

For the full paper please visit ASME's Digital Collection.

Current design theory lacks a systematic method to identify what designers know that helps them to create innovative products. In the early stages of idea generation, designers may find novel ideas come readily to mind, or may become fixated on their own or existing products. This may limit the ability to consider more, and more varied candidate concepts that may potentially lead to innovation. To aid in idea generation, we sought to identify “design heuristics,” or “rules of thumb,” evident in award-winning designs. In this paper, we demonstrate a content analysis method for discovering heuristics in the designs of innovative products. Our method depends on comparison to a baseline of existing products so that the innovative change can be readily identified. Through an analysis of key features and functional elements in the designs of over 400 award-winning products, forty heuristic principles were extracted. These Design Heuristics are outlined according to their perceived role in changing an existing product concept into a novel design, and examples of other products using the heuristics are provided. To demonstrate the ease of use of these Design Heuristics, we examined outcomes from a classroom study, and found that concepts created using Design Heuristics were rated as more creative and varied. The analysis of changes from existing to innovative products can provide evidence of useful heuristic principles to apply in creating new designs.
 

For the complete article visit ASME's Digital Collection.

Soheil Arastehfar, Ying Liu and Wen Feng Lu
J. Mech. Des 138(3), 031103 (Feb 01, 2016); doi: 10.1115/1.4032396
​
​Digital prototype (DP), as a form of communication media, allows designers to communicate design concepts to users by rendering the physical characteristics, e.g., size, colour, and texture. One important aspect is how well users can estimate the values of the physical characteristics of design concepts through interactions with DPs. Better estimates can lead to better perceptions of the designed attributes closely associated with the physical characteristics, and hence, useful user feedback about design concepts. The correctness of the estimates depends on two crucial factors: the ability of DPs to render physical characteristics and the way DPs are used to communicate physical characteristics in a particular environment and via different input/output devices. To date, little attention has been paid to the latter. Hence, it is important to identify an effective way of using DPs via the effectiveness assessment of various possibilities. This paper introduces a methodology for evaluating the effectiveness of communicating physical characteristics to users using DPs. During user interactions with DPs, the methodology collects user estimates of various physical characteristics and assesses the estimates on three dimensions, i.e., degree of correctness, time to make an estimate and handling of different values. The assessments are then evaluated by statistical analysis to reveal the effectiveness of the way of engaging DPs in helping users correctly and quickly estimate the values. The evaluated effectiveness reflects how successful the way of using a DP is, and also helps to suggest a better approach.  

​ 
Additive manufacturing (AM) techniques provide designers with greater freedom in creating customized products with complex shapes. When major design changes are made to a part, undesirable high cost increments may be incurred due to AM process setting adjustments, challenging designers to explore AM-enabled design freedom while controlling costs at the same time. In this research, we introduce the concept of a variable product platform and its associated AM process setting platform, based on which the design and process setting adjustments can be restricted within a bounded feasible space in order to limit cost increments. Fuzzy Time-Driven Activity-Based Costing (FTDABC) approach is introduced to predict AM production costs based on process settings. The process setting adjustment’s feasible space boundary is identified by solving a multiobjective optimization problem. Design parameter limitations are computed in a Mamdani-type expert system and then used as constraints in the design optimization to maximize customer perceived utility. Case studies on designing an R/C racing car family illustrate the proposed methodology and demonstrate that the optimized additive manufactured variable platforms can improve product performances at lower costs than conventional consistent platform based design.

For the complete article please see ASME's Digital Collection.

​Computational Design Synthesis (CDS) methods can be used to enable the computer to generate valid and even creative solutions for engineering tasks. In grammatical approaches to CDS, formal grammars are used to represent a desired design language. This language consists of vocabulary that usually describes components and subsystems of a design and a set of grammar rules that describe possible design transformations. The formalized engineering knowledge can then be used by the computer to synthesize designs. For most engineering tasks, two different kinds of rules are required: rules that change the topology of a design, i.e. how the components are connected, and rules that change parameters of a design. One of the main challenges in CDS using topologic and parametric grammar rules is to decide a priori which type of rule to apply in which stage of the synthesis process as well as whether to start from a valid design and perturb it or to start from a void design. The research presented in this paper compares different strategies for topologic and parametric rule applications during automated design synthesis driven by a search algorithm. The presented strategies are compared considering quantity and quality of the generated designs. The effect of the strategies, the selected search algorithm, and the initial design, from which the synthesis is started, are analyzed for two case studies: the synthesis of gearboxes and of bicycle frames. Results show that the effect of the strategy is dependent on the design task and recommendations are given on which strategies to use for which design task.