The effect of lubricant inertia on fluid cavitation for high-speed squeeze film dampers

This work studies the effect of lubricant inertia on the fluid cavitation for partially sealed high-speed squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs). The lubricant cavitation is modeled by both the Elrod algorithm and the Gumbel’s cavitation boundary condition to provide the comparison between the most common lubricant cavitation models. Additionally, the fluid inertia is integrated by adapting a finite-length SFD model for partially sealed dampers. The integrated SFD model is incorporated into a numerical simulation model and the results are validated by comparison with experimental data. The results of the analysis demonstrate that the fluid inertia effects significantly extend the cavitation region and influence the cavitation onset and the film reformation

On the bead design in LFT structures: The influence of manufacturing-induced residual stresses

In the design of long fibre reinforced thermoplastic (LFT) structures, there is a direct dependency on the manufacturing. Therefore, it is indispensable to integrate the manufacturing influences into the design process. This not only offers new opportunities for material- and load-adapted designs, but also reduces cost-intensive modifications in later stages. The goal of this contribution is to make the complexity manageable by presenting a method which couples LFT manufacturing and structural simulations in an automated optimization loop. Herein, the influence of linear-elastic, local anisotropic material properties as well as residual stresses resulting from the compression molding of LFT on the stiffness-optimized design of beaded plates is investigated. Based on the simulation studies in this contribution, it can be summarized that the resulting bead height and flank angle, considering anisotropies and residual stresses, are smaller compared to isotropic modelling. As a conclusion, the strength constraint limits the maximum bead height and the flank angle needs to be additionally chosen as a consequence of the local fibre orientations and residual stresses resulting from manufacturing. Optimized bead cross sections are only valid for a specific system under investigation, as they depend on the defined boundary conditions (load case, initial charge geometry and position, fibre orientations, etc.)

Design And Optimization Of A Novel Beam-Based Shimmy Damper

Shimmy damper is a passive solution for undesirable oscillations in landing gears. Although it mitigates shimmy to an allowable degree, it can introduce weight, cost, and reliability penalties especially when retrofitted to existing gears. In this report, early investigations into a novel shimmy damper are presented. This damper is suitable for existing and new landing gears and is based on replacing a torque link member with a combination of springs and dampers to suppress the shimmy. The damper is then optimize

The Evaluation Of Modelling Techniques For Lubricant Cavitaion In The Application Of Squeeze Film Dampers

Squeeze film damper (SFD) is widely adopted in turbo-engines to suppress the rotor vibration. However, the prediction of SFD performance is complicated due to the inevitable occurrence of lubricant cavitation. This paper shows the application of three different cavitation algorithms for SFD with sealed conditions. In particular, the linear complementarity problem (LCP) method, which is advanced from a previous research study, is applied to compare results from the well-known methods, i.e. the π-film model and the Elrod cavitation method, for SFD executing circular centered orbits with fully degassed lubricant in the absence of oil feeding. Moreover, numerical models are developed incorporating the mentioned algorithms to predict the hydrodynamic pressure distribution over the cavitated fluid film. Results show that the conventional π-film model over-estimates the cavitation region but under-estimates the reaction force

Reference System Element Identification Atlas – methods and tools to identify references system elements in product engineering

Companies target innovations, successful new products. One major challenge is to increase efficiency and decrease the risk of developing new successful products. We want to reach these goals by improving the reusability of already existing knowledge elements extracted from e.g., already existing (sub-)systems or their documentation. These elements are called reference system elements and are meant to be the starting point for product development projects. Based on a systematic literature review complemented by an expert workshop and analysis of established methods and tools in product engineering, we developed the Reference System Elements Identification Atlas to support the identification of suiting reference system elements. Within the Reference System Elements Identification Atlas, we collected 30 methods and tools to identify reference system elements and allocated them to the various knowledge spaces they search. All 30 methods and tools were grouped in five clusters – creativity methods, data analysis methods, market/competition analysis methods, similarity methods, and trend analysis methods. We observed that methods and tools are hardly related to the identification of reference system elements in literature explicitly. We believe the Reference System Elements Identification Atlas provides valuable support to collect valuable reference system elements as the starting point in product engineering

Numerical Investigations Of Aerodynamic Noise Due To Flow Past A Bluff Body

Paper presented at 2018 Canadian Society of Mechanical Engineers International Congress, 27-30 May 2018.Landing gears (LG) are primarily designed to support all the loads of an aircraft during landing, taxiing, and taking off. To ease inspection and maintenance, the aerodynamic design is not refined, where many components are exposed to the air flow generating what so-called aeroacoustics noise. To understand the underline physics and investigate both the flow field and its associated acoustic field, a two-dimensional (2D) case of flow past a circular cylinder was simulated using ANSYS Fluent. Two different Reynolds numbers, Re, 150 and 90,000 were examined. For low Re, two distinct numerical conditions steady and unsteady flow were simulated and compared to examine the effect of the time dependency on the associated acoustic field. For high Re, the acoustic field was computed using the built-in Ffowcs William and Hawkings (FW-H) acoustic analogy solver in Fluent. The results show the importance of considering the time variable to extract the corresponding flow data. The far-field noise prediction highly depends on the location of the near-filed data and its associated integral source terms (surface/volume)

Design, Prototyping, and Programming of a Bricklaying Robot

This paper presents the development of a Bricklaying Robot capable of building entire walls. This project was motivated by opportunity of automation in construction, which remains costly and inefficient. Several studies have described specialized robot for masonry works, most of them incorporating the human arm concept that requires complex programming and low productivity. In order to improve this model, an innovative concept of a short arm assembled into a lift platform was introduced in this paper. The robot was modeled in Solidworks®, followed by motion study and dynamic analysis to optimize the model. A prototype in 1/4 scale was built to demonstrate its feasibility, detecting and correcting flaws. The prototype was tested by programming servo motors using Arduino UNO hardware and C ++ code. Finally, robot kinematics was analyzed in a construction site scenario. Concordance between the virtual simulation and the experimental prototype results demonstrated the functionality and effectiveness of the proposed design. The invention of this Bricklaying Robot will represent a technological advancement in developing new mechanisms and codes, which may be responsible for increasing productivity and reducing risks of masonry construction. Future analysis of global bricklaying market might be conducted to prove its commercial viability. Cet article présente le développement d’un robot de maçonnerie capable de construire des murs entiers. Le projet est motivé par une grande possibilité pour l’automatisation dans le bâtiment, un domaine qui reste malsain, coûteux et inefficace. Plusieurs recherches discutent des robots spécialisés pour les travaux de maçonnerie ; la plupart de ces robots utilisent le modèle du bras humain, une conception qui nécessite la programmation complexe et présente une perte de productivité. Cet article a pour but d’améliorer le modèle courant en explorant une nouvelle conception d’un bras court, assemblé comme une plate-forme élévatrice. Ce robot a été conçu en Solidsorks®, et une étude de mouvement et une analyse dynamique ont été menées pour optimiser le modèle. Un prototype à l’échelle 1:4 a été conçu pour démontrer la faisabilité du robot, tout en détectant et corrigeant ses défauts. Le prototype a été évalué par la programmation des servomoteurs, en utilisant du matériel informatique d’Arduino UNO et le langage de programmation C ++. Finalement, la cinématique du robot a été analysée en un scénario de chantier de construction. La fonctionnalité et l’efficacité de la conception proposée ont été démontrées par la concordance entre la simulation virtuelle et les résultats du prototype expérimental. L’invention de ce robot de maçonnerie constituera une avance technologique dans l’étude et le développement de nouveaux mécanismes et des codes informatiques, qui permettront d’améliorer la productivité et réduire les risques de maçonnerie. Une analyse de marché mondial de maçonnerie peut être menée à l’avenir pour vérifier la viabilité commerciale du robot