Topology Optimization of Plastic Parts for Injection Molding

Topology optimization is broadly recognized as a design approach to generate high-performance conceptual designs suitable for freeform fabrication, e.g., additive manufacturing. When other fabrication methods are considered, topology optimization must integrate manufacturing constraints. The integration of constraints for extrusion and casting has been addressed in the past by a few researcher groups. In this work, extrusion and casting constraints are revisited and extended to include plastic injection. The proposed method relies on the use of intersection planes and the definition of a parting line within the planes. The resulting topologies can be injected in a two-plate mold without the use of inserts. The implementation and results of the proposed approach are demonstrated in classic three-dimensional problems that include a cantilevered beam with different load conditions.

Axiomatic Design to Foster Additive Manufacturing-Specific Design Knowledge

Axiomatic design has the potential to help designers understand the increased design freedom and limitations of additive manufacturing prior to starting the actual design process. The purpose of this study is to verify the usefulness of Axiomatic Design in the design process of complex additively manufactured components. The article uses a case study involving the design of a non-assembly turbine to demonstrate that Axiomatic Design can be applied as a supportive tool to acquire information on new limitations imposed by additive manufacturing, such as minimum wall thickness and maximum size of parts. The use of axiomatic design is demonstrated by describing the process of decomposition of the non-assembly turbine and examining the suitability of the general design according to the independence axiom. The resulting decomposition chart is subsequently used as a basis by the authors to design individually two competing designs of a turbine. Finally, the information axiom is used to determine the design with the lowest information content according to design (part and support volume), performance (pressure drop) and economic parameters (cost).

Design and Start-Up of a Plant for Dairy Processed Sweets

The industry of processed dairy and fruit sweets is listed in the agroindustry as one of the most representative at the economic level preceding poultry and oil palm production. In addition, the requirements of safety and product quality that are indispensable, it also requires committed and specialized labor generating a social impact in terms of employability and competitiveness of the companies that make up the production chain. The production process is carried out in an artisanal way, therefore, one of the problems faced by this industry is the absence of technology and / or automation that allows them to improve process times and, consequently, productivity. However, this can be solved with the incorporation of systems that optimize the acquisition and control of the process variables of cooking and dosing of the sweet, reducing the costs due to waste and poor handling of its ingredients, as well as reaching higher production levels with quality and products that meet the standards imposed by globalized markets. This article shows the development, implementation and start-up of a pilot plant for the cooking and dosing of the sweet, taking into account that the capacity of the hopper is 70 liters. The results show a considerable improvement in the quality and process standards, as well as establishing criteria to optimize other variables that appear in the development.

A Compared Approach on How Deep Learning May Support Reverse Engineering for Tolerance Inspection

Reverse Engineering (RE) may help tolerance inspection during production by digitalization of analyzed components and their comparison with design requirements. RE techniques are already applied for geometrical and tolerance shape control. Plastic injection molding is one of the fields where it may be applied, in particular for die set-up of multi-cavities, since no severe accuracy is required for the acquisition system. In this field, RE techniques integrated with Computer-Aided tools for tolerancing and inspection may contribute to the so-called “Smart Manufacturing”. Their integration with PLM and suppliers’ incoming components may set the information necessary to evaluate each component and die. Intensive application of shape digitalization has to front several issues: accuracy of data acquisition hardware and software; automation of experimental and post-processing steps; update of industrial protocol and workers knowledge among others. Concerning post-processing automation, many advantages arise from computer vision, considering that it is based on the same concepts developed in a RE post-processing (detection, segmentation and classification). Recently, deep learning has been applied to classify point clouds, considering object and/or feature recognition. This can be made in two ways: with a 3D voxel grid, increasing regularity, before feeding data to a deep net architecture; or acting directly on point cloud. Literature data demonstrate high accuracy according to net training quality. In this paper, a preliminary study about CNN for 3D points segmentation is provided. Their characteristics have been compared to an automatic approach that has been already implemented by the authors in the past. VoxNet and PointNet architectures have been compared according to the specific task of feature recognition for tolerance inspection and some investigations on test cases are discussed to understand their performance.

Optimum Synthesis of Rigid Mechanisms Using a Dynamic Ant-Search Method With Sensitivity Analysis

Four-bar linkages are commonly used mechanisms in various mechanical systems and components. Several techniques for optimum synthesis of planar mechanisms have been suggested in literature such as the Genetic, Tabu, Simulated Annealing, Swarm-Based and many other algorithms. This paper covers optimization of four-bar mechanisms with path generation tasks using a Dynamic Ant Search (DAS) algorithm. Unlike the Modified Ant Search (MAS) technique where ants unanimously moved between the exploration and exploitation phases, in the proposed algorithm, each ant is free to travel between the two aforementioned phases independent of other ants and as governed by its own pheromone intensity level. Moreover, sensitivity analysis is conducted on the design parameters to determine their corresponding neighborhood search boundaries and thus improve the search while in the exploitation mode. These implemented changes demonstrated a remarkable impact on the optimum synthesis of mechanisms for path generation tasks. A briefing of the MAS based algorithm is first presented after which the proposed modified optimization technique and its implementation on four-bar mechanisms are furnished. Finally, three case studies are conducted to evaluate the efficiency and robustness of the proposed methodology where the performances of the obtained optimum designs are benchmarked with those previously reported in literature.

Influence of Geometric Shape Defects on Operating Parameters in Cylindrical Journal Bearings

Very high quality standards need to be guaranteed for the manufacturing of cylindrical journal bearings due to their sensitive lubrication gap geometry as Iwamoto and Tanaka [1] have shown years ago. Even geometric deviations of a few micrometers can lead to considerable functional impairments. However, the designer’s actual geometric specification (technical drawing) mainly serves as information for the nominal geometry and important fits. Within this research project, the main aim was to find out how permissible deviations on nominal operating parameters can be translated into permissible geometric shape deviations and their specifications as described in ASME Y14.5 [7]. The outcome was the development of a tolerance evaluation matrix which quantifies the relation between geometric and operating parameter deviations. For this, existing references and standards dealing with geometric defects of journal bearings were analyzed as in [1], [2] and [3]. Firstly, to investigate the roundness deviation, we focused on the form of equal thickness because this occurs most often in the manufacturing process of cylindrical journal bearings. Later on, the shape deviation of parallelism (cone) and its combination with the roundness (equal thickness) were also investigated. After simulating the parameter variation of about 200,000 operating points with a hydrodynamic simulation program, called ALP3T, we synthesized a tolerance evaluation matrix for the application during the engineering and design process of cylindrical journal bearings.

Design for Additive Manufacturing: Effectiveness of Unit Cell Design Guidelines As Ideation Tools

The periodic cellular materials are comprised of repeatable unit cells. Due to outstanding effective properties of the periodic cellular materials such as high flexibility or high stiffness at low relative density, they have a wide range of applications in lightweight structures, crushing energy absorption, compliant structures, among others. Advancement in additive manufacturing has led to opportunities for making complex unit cells. A recent approach introduced four unit cell design guidelines and verified them through numerical simulation and user studies. The unit cell design guidelines aim to guide designers to re-design the shape or topology of a unit cell for a desired structural behavior. While the guidelines were identified as ideation tools, the effectiveness of the guidelines as ideation tools has not been fully investigated. To evaluate the effectiveness of the guidelines as ideation tools, four objective metrics have been considered: novelty, variety, quality, and quantity. The results of this study reveal that the unit cell design guidelines can be considered as ideation tools. The guidelines are effective in aiding engineers in creating novel unit cells with improved shear flexibility while maintaining the effective shear modulus.

Reliability-Based MDSDO for Co-Design of Stochastic Dynamic Systems

Optimization of dynamic engineering systems requires an integrated approach that accounts for the coupling between embodiment design and control system design, simultaneously. Generally known as combined design and control (co-design) optimization, these methods offer superior system performance and reduced costs. Despite the widespread use of co-design approaches in the literature, not much work has been done to address the issue of uncertainty in co-design problem formulations. This is problematic as all engineering models contain some level of uncertainty that might negatively affect the systems performance, if overlooked. While in our previous study we developed a robust co-design approach, a more rigorous evaluation of probabilistic constraints is required to obtain the targeted reliability levels for probabilistic constraints. Therefore, we propose and implement a novel stochastic co-design approach based on the principles of reliability-based design optimization (RBDO). In particular, a reliability-based, multidisciplinary dynamic system design optimization (RB-MDSDO) formulation is developed using the sequential optimization and reliability assessment (SORA) algorithm, such that the dynamic equality constraints are satisfied at the mean values of random variables, as well as their most probable points (MPPs). The proposed approach is then implemented for two case studies to indicate the impact of including reliability measures in co-design formulations.

Motorcycle No Fall Over Kickstand

Motorcycles have been a mode of transportation since 1894, when the first batch of motorcycles were manufactured for consumer use by Hildebrand & Wolfmüller. Motorcycles provide a fast and cost effective, specifically fuel economy, way to commute. They are also used in recreational settings such as motocross and performance racing activities. Over the years, there have been many different design generations for the various manufactures and custom shops. The customer demand for motorcycles is always increasing as well. However, the biggest drawback to someone owning and operating a motorcycle has always been safety concerns. One of these safety concerns is the motorcycle falling over and being damaged while being parked. Fall overs occur for a multitude number of reasons, the most common occurrences due to being parked on an uneven level or someone pushing the motorcycle over. Current safety devices to prevent this from occurring are crash bars and center stands. However, these devices are either not applicable to all motorcycle makes and models or do not appeal to the motorcycles look per the owner’s discretion. A “no fall over” automated mechanical kickstand would solve both of these problems and, at the same time, prevent fall over accidents.

Gait Analysis in the Assessment of Patients Undergoing a Total Hip Replacement

Nowadays, healthcare centers are not familiar with quantitative approaches for patients’ gait evaluation. There is a clear need for methods to obtain objective figures characterizing patients’ performance. Actually, there are no diffused methods for comparing the pre- and post-operative conditions of the same patient, integrating clinical information and representing a measure of the efficiency of functional recovery, especially in the short-term distance of the surgical intervention. To this aim, human motion tracking for medical analysis is creating new frontiers for potential clinical and home applications. Motion Capture (Mocap) systems are used to allow detecting and tracking human body movements, such as gait or any other gesture or posture in a specific context. In particular, low-cost portable systems can be adopted for the tracking of patients’ movements. The pipeline going from tracking the scene to the creation of performance scores and indicators has its main challenge in the data elaboration, which depends on the specific context and to the detailed performance to be evaluated. The main objective of this research is to investigate whether the evaluation of the patient’s gait through markerless optical motion capture technology can be added to clinical evaluations scores and if it is able to provide a quantitative measure of recovery in the short postoperative period. A system has been conceived, including commercial sensors and a way to elaborate data captured according to caregivers’ requirements. This allows transforming the real gait of a patient right before and/or after the surgical procedure into a set of scores of medical relevance for his/her evaluation. The technical solution developed in this research will be the base for a large acquisition and data elaboration campaign performed in collaboration with an orthopedic team of surgeons specialized in hip arthroplasty. This will also allow assessing and comparing the short run results obtained by adopting different state-of-the-art surgical approach for the hip replacement.