The Development of Computer Models for Ergonomic Accommodation

Additive manufacturing has opened the door to the creation of lightweight lattice structures. However, present Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) software are unsuitable for these types of structures. The objective of this research is to examine the performances of current CAD and CAE software to design lattice structures and to demonstrate their limitations and propose requirements for future developments. A performance evaluation of a case study for lattice structure designs was conducted. The criteria used for the evaluation were CAD human-machine-interface, RAM consumption, data exchange between CAD, CAE and CAM tools and finite element analysis (FEA) duration and file sizes. The CAD tool was incapable of executing a repetition function for octet-truss lattice structures of 150 x 150 x 150 mm dimensions or larger and the software stopped working. For 70 × 70 × 70 mm octet-truss lattice structure, the FEA computation file size reached 36.6 GB. The CAD file size of a 200 x 200 x 200 mm octet-truss lattice structure reached nearly 290 MB. In conclusion, this study exposes the performance inadequacy of current CAD and CAE tools and CAD file formats to design lattice structures for additive manufacturing parts.

Searching and handling geometric data are basic requirements of any Computer Aided Engineering application (CAE). Spatial search and local search has greater importance in CAD and CAE applications for reducing the model preparation time. There are many efficient algorithms being made to search geometrical data. Current neighbour search strategy is limited and not efficient in different CAE platforms. R-tree is tree data structure used for spatial access methods. This paper presents a review of R-tree data structure with its implementation in one of the CAE tool for neighbour search and local search. It satisfies current neighbour search requirements in CAE tools. Results shows considerable amount of time saving compared to the conventional approach. This work concludes that R-tree implementation can be helpful in identifying neighbour part and reducing model preparation time in CAD and CAE tools.

Field programmable gate array (FPGA) devices, heavily used in spacecraft electronics, have grown substantially in size over the past few years, causing designers to work at a higher conceptual level, with computer aided engineering (CAE) tools synthesizing and optimizing the logic from a description. It is shown that the use of commercial-off-the-shelf (COTS) CAE tools can produce unreliable circuit designs when the device is used in a radiation environment and a flip-flop is upset. At a lower level, software can be used to improve the SEU performance of a flip-flop, exploiting the configurable nature of FPGA technology and on-chip delay, parasitic resistive, and capacitive circuit elements.

This article is going to contemplate the steps involved in the conception of an AC/DC integrated converter with the power factor correction (PFC) stage applied in an Organic Light-Emitting Diode (OLED) driver. An approach about converter design with emphasis in magnetic elements will be performed, such approach includes the support and design validation by computer-aided engineering (CAE). The obtained results show the viability of using CAE tools in power converters concept being useful for the power electronics designers that is looking to optimize their projects.

Fatigue has long been identified as a human factor in aviation. Subsequently, a series of studies have highlighted fatigue-related elements within the context of the aviation industry, focusing on the flight deck – with some extension to flight students – and aviation maintenance activities. However, the latter has not been as deeply examined as its flight crew-centered counterpart. Similarly – if not more significantly – fatigue experienced by aircraft maintenance technician (AMT) students is scarcely explored, especially in comparison to the research conducted to understand fatigue in flight schools. AMT students are subject to comparable, but not the same, experiences as flight students. Academic-related stress, coupled with the need to accumulate a certain number of hours of instruction, certification and qualification exams, and the careful balance of jobs, academic requirements and expectations, and personal lives are all examples of fatigue-inducing situations faced by AMT students. In the conducted study, exactly these factors were explored, with the goal of better understanding the fatigue levels experienced by aircraft maintenance students, but also the contributing factors thereto and the consequences thereof. With this purpose, AMT students at a specialized school in the United States were surveyed with respect to their opinions on, and experiences with, fatigue. A total of 72 responses were analyzed, which indicated that fatigue and tiredness are factors of interest within the context of AMT educational programs. While the participants indicated overall healthy lifestyle patterns and adequate stress and work-life balancing mechanisms, commitments outside of the classroom, the schedule of classes, and course attendance requirements were identified to contribute to students’ fatigue levels. Consequently, reports of students falling asleep in class together with fatigue-induced errors/mistakes were identified among the responses. Nevertheless, the participants indicated to be aware of the safety issues created by fatigue and noted that their learning was not detrimentally impacted by their levels of fatigue. The results obtained form a basis for future research efforts, highlighting areas that are of specific interest for future studies with the goal of improving the educational experience for future aircraft maintenance technicians.

In the last decade, many industries introduced the Computer-Aided-Engineering (CAE) tools in order to decrease the number of prototype builds and to speed up the time of the development cycle. Although such analytical tools are relatively inexpensive to use and faster to implement as compared to the costly traditional testing design process; however, there are many variables that CAE tools cannot adequately consider, such as manufacturing processes, assembly, material anisotropy, and residual stresses. Therefore, still smart testing is required to validate the CAE results.

In the past decade, the mechanical engineering industry has searched for a design methodology that could systematically unify the support of computer-aided engineering (CAE) tools for the design process. More recently, some propositions have been put forward for the CAE-driven design process (CDDP), but the efficiency of these design processes is questionable. We have proposed improvements and new arrangements that result in the integrative CDDP (ICDDP), which makes CDDP more reliable, efficient and predictive. The ICDDP redefines the role of CAE tools and positions the optimization technology as a fundamental driving force behind the whole design process. Consequently, the ICDDP orders design phases as: (1) conceptual design, (2) design crystallization and (3) design sophistication, which steer the design process sequentially. The accurately established linkages between the sequential design steps enhance the smooth recurrence of the ICDDP for new product executions. In addition, this work demonstrates the application of the conceptual design phase to design a new L7e (eQuad) vehicle structure. This phase of the ICDDP illustrates the specific steering methodology for the topology optimization of a new eQuad structure as well as the geometric solution derivation step that reveals the transformation of bionic shapes into rough manufacturable geometry. Additionally, the numerical verification of the simple geometric model is presented for the load cases given. Our results exemplify the fact that the ICDDP allows engineers to design new innovative and lightweight structures.

A new technique for the computer modeling of fluid-loaded magnetomechanical transducers is presented. This numerical technique is based on a finite-element method (FEM) and allows the precise calculation of the magnetic, mechanical, and acoustic fields, including their couplings. Further on, nonlinear effects in the mechanical and magnetic behavior are considered. Therewith, the complex dynamic behavior of electrodynamic loudspeakers was studied and, furthermore, an appropriate computer-aided engineering (CAE) environment has been established. This CAE tool allows an optimization of critical parameters, for example: The validity of the computer simulations is verified with the help of appropriate measurements. The calculated and measured values for eigenfrequencies, axial pressure responses, and electrical input impedances are in excellent agreement. The applicability of the presented calculation scheme with respect to the computer-aided design of moving coil drivers is demonstrated by reporting several practical applications, which are of great interest for loudspeaker manufacturers. In the present paper, the elimination of response dips at intermediate frequencies, the calculation of polar responses, and the examination of the so-called jump-out excursion, are presented.

Rubber isolators are mounted between a cooling module and a carrier to isolate the car body from vibration due to the rotation of the cooling fan. The isolators should be durable against fatigue loads originating from fan rotation and road disturbance. Thus, the design of rubber isolators is required to maximize both vibration isolation and fatigue life. In this study, the shapes of the rubber isolators are optimally designed using a process integration and design optimization (PIDO) tool that integrates the various computer-aided engineering (CAE) tools necessary for vibration and fatigue analyses, automates the analysis procedure and optimizes the design solution. In this study, we use CAE models correlated to the experimental results. A regression-based sequential approximate optimizer incorporating Process Integration, Automation and Optimization (PIAnO), a commercial PIDO tool, is employed to handle numerically noisy responses with respect to the variation in design variables. Using the analysis and design procedure established in this study, we successfully obtained the optimal shapes of the rubber isolators in two different cooling modules; these shapes clearly have better vibration isolation capability and fatigue lives than those of the baseline designs used in industry.

The shortage of medical-grade personal protective equipment for frontline healthcare workers is an important issue during the ongoing COVID-19 pandemic. The demand placed on textile manufacturers to rapidly produce products that adhere to a set of standard quality assurance requirements has increased dramatically, leading to increased burden on quality assurance floors and national testing labs. Standardized testing of protective equipment is a labor-intensive and time-consuming process that requires human operators to perform tasks that can be automated using various technologies, such as collaborative robots and computer vision systems. The tests we focus on involve evaluating surgical masks and protective materials for blood penetration resistance, flammability, and liquid barrier performance. This work introduces a test cell designed to accommodate human operators in completing various quality assurance tests for protective equipment. The test cell is comprised of custom-designed cases containing test specimens to facilitate robot manipulation and cameras to monitor and characterize the test results. We demonstrate how the system can reduce the workload and reliance on human operators at no expense to the quality assurance process. Based on validation test results and user experience, it is predicted that the human operator will only have to prepare cases with test specimens and handle infrequent failures that occur within the system, without compromising overall completion time. We envision that this system will relieve the strain on textile manufacturing processes requiring human labor to repeatedly perform simple tasks.

A method for optimal material selection aided with decision making theory

Large-capacity power electronics in the range of MW or more has large physical dimensions, heavy weight and high power dissipation although the efficiency is high enough. These features sometimes put difficulties into the development only by the hardware prototypes. Then, CAE (Computer Aided Engineering) technology is now going to be applied to overcome some of difficult and complicated designs of parasitic inductance, thermal performance, mechanical strength and so on. The paper summarized trend of CAE technology application by introducing actual examples. The simulation results of CAE tools are evaluated by experiments with actual prototypes. In summary, the CAE technology of these days is found contributing effectively to the development process of large-capacity power electronics equipment.

Conventional textile-reinforced materials for personal body protective equipment (PBPE) often fail to adequately reduce risk of severe injuries, shocks, jerks, and wounds from external physical forces. In contrast, advanced high performance synthetic and bio-natural materials offer superior impact strength, resilience, toughness, elasticity, durability, and tensile properties, making them ideal for absorbing, transmitting and dissipating impact kinetic energy and localised impulses over larger surface areas of the human body. Considering this, the current scientific study leverages the exceptional mechanical properties of these materials through an iterative laminate design approach, employing sandwich-structured polymer matrices along with focussing on the enhanced structural properties of complex and biomimetic geometries in the composite material’s microstructures for extraordinary protection and novel results. The design process uses computer-aided engineering (CAE) simulations and finite element analysis (FEA) method for testing the composite material, incorporating non-linear dynamic models with real-world impact conditions. The research ensures material selection, conformability and structural optimisation, while post-simulation data analysis provides critical information and statistical insights for refining the human-centred composite material, while also addressing the practical challenges related to manufacturability and scalability of the final design, essentially proposing a virtually validated, digitally driven, design methodology for improving occupational safety and enhancing user comfort.

Critical analysis of tools for computer-aided software engineering

We present a newly developed computer aided engineering (CAE) tool for the design of capacitative micromachined sound and ultrasound transducers. The numerical scheme is based on the finite element (FE) method and takes all relevant nonlinearities (geometric nonlinearity of the mechanical structures, electrostatic force, moving body in an electrostatic field) and couplings between the different physical fields (electrostatic, mechanical and acoustical fields) into account. The applicability of the CAE tool is demonstrated by two practical examples: mechanical and acoustic crosstalk in capacitative micromachined ultrasound transducers (CMUTs) and total harmonic distortion of micromachined silicon microphones.