This paper explores the formal roles of non-functional requirements’ (NFR) elicitation, definition, and verification in the early stages of an engineering design project. This is performed using a case study conducted at an automotive original equipment manufacturer (OEM) during the design and development of a rear bumper sub-system. The purpose of this exploration is to determine if NFRs should be formalized within requirements modeling scheme. This can capture conceptual design information to identify their impact on other requirements while conducting design changes. The modeling scheme in this paper consists of a sequence of following domains—requirements, functions, working principle, components, design parameters, test measures, and tests—that are mapped to each other using matrices. It is revealed through this case study that non-functional requirements drive much of the design decision-making process and constrain the manner in which the product functionality is realized. Hence, the inclusion of NFRs as a separate and distinct domain in the design process is critical to recognize their significance during design changes. Based on the observations made in the case study, the NFR domain is included in the requirements modeling scheme.

Designing products for recyclability is driven by environmental and economic goals. Several design for assembly (DFA) rules and parameters can be used to gauge the recyclability index of product designs. These indices can be used for comparative analysis of the recyclability of different products. This assists the designer in making design choices related to the product's end of life. However, many of the existing recyclability indices are only available after design and manufacturing decisions are made. If such design decisions could be made earlier in the design process, when the design space is less bound, recyclability could be considered earlier. A case study is performed to determine if DFA parameters could be utilized to determine product recyclability. The parameters were obtained from existing DFA time estimate tables. The results of the study indicated that the recyclability of the product, as defined by established recyclability metrics, could be predicted through DFA measures. A negative correlation was realized between recyclability and insertion time. Components that required greater time to mate during assembly adversely affected the recyclability of the product. Conversely, handing time was found to have no predictive capability on product recyclability. These findings are used to develop a recyclability index that utilizes the DFA measures, allowing designers and engineers to determine recyclability earlier in the design process.

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Recent advances in additive manufacturing technologies have already led to the wide-scale adoption of 3D-printed parts in the aerospace, medical, automotive, tooling, and electronics industries. The expansion in choice of materials that can be processed, in particular, using fused deposition modeling (FDM), selective laser sintering/melting, and stereolithography, and the steady advancements in dimensional accuracy control, have extended the range of applications beyond rapid prototyping. However, additive manufacturing still has considerable limitations compared to traditional and subtractive manufacturing processes. This work addresses limitations associated with the as-deposited surface roughness of 3D-printed parts. The effects of roughness-induced stress concentrations on the mechanical strength were studied, and ultrafast laser postprocessing was utilized to reduce the surface roughness of 3D-printed parts. The samples were manufactured using a commercial desktop FDM system and standard ASTM flat dogbone geometries. The samples were then postprocessed with a high-repetition-rate ultrafast Yb-fiber laser using a multi-layer scan approach. This novel postprocessing method enables high-efficiency material removal without inducing excessive thermal residual stresses into the material and, therefore, is suitable for postprocessing thermally sensitive materials, such as PLA and other polymers as well as parts with engineered porosity. In this work, we vary laser process parameters, such as average power and number of laser-processed layers, to achieve various levels of surface roughness. Values of tensile strength of the specimens were compared between 3D-printed samples featuring initial roughness and laser postprocessed samples with different values of surface roughness. The results indicate that the laser-processed samples exhibit an almost 10% increase in tensile strength depending on specific laser processing parameters.

Designing products for recyclability is driven by environmental and economic goals. Several Design for Assembly rules and parameters can be used to gauge the recyclability index of product designs. These indices can then be used for comparative analysis of the recyclability of different products. This would assist the designer in making design choices related to the end of the product’s life cycle. Further, such design decisions could be made earlier in the design process, when the design space is less bound. A case study was conducted for different products to compare their recyclability indices. The parameters were obtained from existing Design for Assembly time estimate tables. The results of the study indicated the recyclability of the product, as defined by established recyclability metrics, could be predicted through design for assembly measures. A statistically significant negative correlation was realized between recyclability and insertion time. Effectively, components that required greater time to mate during assembly adversely affected the recyclability of the product. Conversely, handing time was found to have no predictive capability to product recyclability.