Abstract: Hydraulic systems in aircrafts largely comprise of metallic components with high strength to weight ratios which comprise of 2024 Aluminum and Titanium Ti-6AL-4V. The selection of material is based on low and high pressure applications respectively. For aircraft fluid conveyance products, hydraulic conduits are fabricated by axisymmetric turning to support flow conditions. The hydraulic conduits further carries groves within for placement of elastomeric sealing components. This article presents a systematic study carried out on common loads experienced by fluid carrying conduits and the failure modes induced. The critical failure locations on fluid carrying conduits of 2024-T351 Aluminum was identified, and the Scanning Electron Microscope (SEM) analysis was carried out to identify the characteristic footprints of failure surfaces and crack initiation. Through this analysis, a load to failure mode correlation is established.
Polyurethane foams (PUF) are a class of cellular polymers with a large range of applications. It is possible to control some properties of PUF by adjusting some chemicals, aiming to reach the best performance with lower cost, weight and process easiest. On the same way, graphene and its derivatives may be used for the modification of PUF, aiming to improve many properties. Depending on the dispersion technique, increases in mechanical, dynamical mechanical, thermal and acoustical properties may be reached, even when a low content of the nanomaterial is employed. This brief review presents some techniques used for the dispersion and incorporation of graphene and its derivatives into PUF, focusing on the enhancement of acoustical applications. Some techniques such as mechanical stirring, sonication and layer-by-layer are presented. It was observed that depending on the techniques, a real and significant difference was observed in some properties, mainly in acoustical
DHT hybrid transmission assembly control system discussed in this paper includes hydraulic control, drive mode switching control, shift control, dual motor control, clutch and motor thermal management. Hydraulic control includes torque-pressure conversion. Including clutch pressure kp adaption, clutch gain adaption, clutch oil filling time adaption. Shift control includes shift type decision, shift timing control, shift torque exchange process control, shift inertia process based on motor intervention. Thermal management includes clutch flow and motor flow distribution. Motor control include the current control, mode control and boost strategy of permanent magnet synchronous motor in dual hybrid system, which has good stability and robustness. Current control includes current vector control, MTPA control, flux weakening control, PI current control and SVPWM control.
The automatic transmission of a specialized vehicle experienced the issue of unstable oil charge time due to the significant variability of related parameters and the non-linear trend of individual product parameter changes over time. To investigate the underlying causes of this phenomenon and the improved oil charge effect, a detailed model of the clutch oil charge process during gear shifting was established in this paper, which included dynamic models of components such as the hydraulic system, clutch, proportional valve, and pumps. The influence of parameters such as orifice diameter, piston gap, and oil filling flow rate on the system response was taken into account. Dynamic simulations were conducted to study the impact of these parameters on the clutch oil charge time. Additionally, physical experiments were performed using a test bench to provide a comparison with the simulation results.
With the recent development of electric vehicles, the demands of Lithium-ion batteries and advanced battery technologies are growing. Today, Lithium-ion batteries mainly use liquid electrolyte, which contains organic compounds such as dimethyl carbonate and ethylene carbonate as solvents for the Lithium salts. Thermal runaway is a complex process which can involve electrolyte decomposition and subsequent venting of combustible gases that could be readily ignited when mixed with air, leading to pronounced heat release from the combustion of the mixture. The chemical behavior of electrolyte during thermal runaway of Lithium-ion batteries is a critical process and needs to be part of thermal runaway modeling. Well validated, small size chemical kinetic mechanisms of the electrolyte components are required to describe this process in CFD simulations. In this work, sub-mechanisms of dimethyl carbonate and ethylene carbonate were developed and adopted in Ansys Model Fuel Library (MFL).
This paper details testing for torque converter clutch characterization during steady state and dynamic operation under controlled slip conditions on a dynamometer setup. The subject torque converter under test is a twin plate clutch with a dual stage turbine damper without a centrifugal pendulum absorber. An overview is provided of the dynamometer setup, hydraulic system and control techniques for regulating the apply pressure to the torque converter and clutch. To quantify the performance of the clutch in terms of control stability, pressure to torque relationship and the dynamic behavior during apply and release, a matrix of oil temperatures, output speeds, input torques, and clutch apply pressures were imposed upon the torque converter.
Positive displacement pumps are key components in automotive and hydraulic fluid systems, often serving as the primary power source and a major source of noise in both on-highway and off-highway vehicles. Specifically, gerotor pumps are widely utilized in vehicle coolant, lubricating, and other fluid systems for both conventional and electric powertrains. This study introduces a novel method for predicting noise in gerotor pumps by combining a Computational Hydro-Acoustics approach with a 3D Computational Fluid Dynamics (CFD) approach, both implemented in the Simerics-MP+ code. The CFD simulation includes the detailed transient motion of the rotors (including related mesh motion) and models the intricate cavitation/air release phenomena at varying pump speeds. The acoustic simulation employs a Ffowcs-Williams Hawkings integral formulation to predict sound generation and propagation based on the detailed flow field predictions from the CFD model.
A semi-active suspension system provides superior safety, ride, and handling performance for a vehicle by continuously varying the damping based on vehicle motions, where semi-active damper is the most critical component. Today, semi-active dampers are standard in the premium segment of vehicles and optional extras in mid-size and compact vehicle segments. Electric vehicles require larger sized dampers to meet heavier vehicle loads and damping force requirements. The aim of this paper is to highlight the design and development methodology of a base valve for larger bore-size for triple tube semi-active hydraulic damper. The workflow follows to present a process for base valve design to meet structural strength requirements, the key steps of design calculations of the hydraulic performance. The design of the base valve and suction disks architecture was engineered with the aid of Computer Aided simulations.
This four-hour short course provides key considerations for the comparison of electrically supplied (Power-by-Wire, or PbW) and hydraulically supplied (Power-by-Pipe, of PbP) actuation for aerospace. The focus is put on the consequence, for designers, of changing the physical principles and the technology used. A particular attention is paid to the unavoidable side effects introduced by the technological realization. Simple examples with realistic numerical values are used to make the comparisons quantitatively realistic.