scholarly journals Model Construction and Performance Degradation Characteristics of a Deflector Jet Pressure Servo Valve under the Condition of Oil Contamination

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yuanbo Chu ◽  
Zhaohui Yuan ◽  
Xuegong He ◽  
Zhichao Dong
Keyword(s):  
Failure Modes ◽  
Structural Characteristics ◽  
Slide Valve ◽  
Performance Degradation ◽  
Dynamics Simulation ◽  
Oil Contamination ◽  
Characteristic Analysis ◽  
Servo Valve ◽  
Output Pressure ◽  
Deflector Jet

The deflector jet pressure servo valve is a kind of high-precision hydraulic component that can be widely used in the antiskid braking system of an aircraft. In actual service, it will be faced with extreme working conditions of gradual oil contamination, which will cause performance degradation and function maladjustment of the whole valve. To this end, the paper proposes a performance degradation characteristic analysis method. In which, firstly, the structural characteristics and working principle of the deflector jet pressure valve are analyzed; then, the entire dynamics model of the pressure valve is built using the braking cavity as the load blind cavity. Secondly, the two main failure modes induced by oil contamination such as erosion wear of pilot stage and stuck of slide valve stage’s valve core are determined based on the engineering experience, aimed at which the failure mechanism is analyzed; then, the sensitivity simulation model of the servo valve’s output pressure with respect to key degradation parameters is established and the sensitivity analysis is performed. Finally, combining the theoretical analysis with multiphysics simulation correction methods, the performance degradation model of the typical failure modes are established, and then, the performance degradation characteristics under dynamic contamination conditions are analyzed, which is combined with the failure threshold determined by the dynamics simulation to finish the service life prediction of the deflector jet servo valve.

scholarly journals Study on Structural Characteristics of China’s Passenger Airline Network Based on Network Motifs Analysis

2019 ◽  
Vol 11 (9) ◽  
pp. 2484 ◽  
Author(s):  
Ying Jin ◽  
Ye Wei ◽  
Chunliang Xiu ◽  
Wei Song ◽  
Kaixian Yang
Keyword(s):  
Airline Industry ◽  
Structural Characteristics ◽  
Building Blocks ◽  
Development Stage ◽  
Network Motifs ◽  
Characteristic Analysis ◽  
Airline Networks ◽  
Airline Network ◽  
Industry Sustainability ◽  
Advanced Development

The air passenger transport network system is an important agent of social and economic connections between cities. Studying on the airline network structure and providing optimization strategies can improve the airline industry sustainability evolution. As basic building blocks of broad networks, the concept of network motifs is cited in this paper to apply to the structural characteristic analysis of the passenger airline network. The ENUMERATE SUBGRAPHS (G, k) algorithm is used to identify the motifs and anti-motifs of the passenger airline network in China. A total of 37 airline companies are subjected to motif identification and exploring the structural and functional characteristics of the airline networks corresponding to different motifs. These 37 airline companies are classified according to the motif concentration curves into three development stages, which include mono-centric divergence companies at the low-level development stage, transitional companies at the intermediate development stage, and multi-centric and hierarchical companies at the advanced development stage. Finally, we found that adjusting the number of proper network motifs is useful to optimize the overall structure of airline networks, which is profitable for air transport sustainable development.

Artificial neural network approach for air brake pushrod stroke prediction in heavy commercial road vehicles

2018 ◽  
Vol 233 (10) ◽  
pp. 2467-2478 ◽  
Author(s):  
Radhika Raveendran ◽  
Apoorva Suresh ◽  
Vignesh Rajaram ◽  
Shankar C Subramanian
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Confidence Interval ◽  
Prediction Error ◽  
Performance Degradation ◽  
Dynamics Simulation ◽  
Brake System ◽  
Road Vehicles ◽  
Prediction Scheme ◽  
Artificial Neural

In heavy commercial road vehicles, the air brake system is a critical vehicle safety system whose performance degradation increases the risk of accidents and hence requires periodic inspection and maintenance. The wear of brake pad lining and brake drum during operation leads to increase in the stroke of a component called pushrod whose ‘out-of-adjustment’ creates severe brake performance degradation. The fact that the driver does not receive a corresponding tactile feedback till it is too severe adds to the complexity of manual detection. Motivated by the increase in onboard sensing, electronics, and computation capabilities, this study proposes an artificial neural network–based approach to predict pushrod stroke based on measurement of brake chamber pressure. Here, a back propagation algorithm was used to train the multilayer feed-forward network. The effect of excessive pushrod stroke on vehicle braking response was first studied using a Hardware-in-Loop system that consists of brake system hardware and a commercial vehicle dynamics simulation software (IPG TruckMaker®). Experimental data collected from this system with manual slack adjuster and automatic slack adjuster have then been used to train and test the artificial neural network for pushrod stroke prediction. The performance of the prediction scheme has been tested over the entire range of brake operating conditions. The prediction error corresponding to manual slack adjuster was found to be within ±15% in 322 out of the entire test set of 328 instances (98.17%) and automatic slack adjuster within ±8% in all 57 test sets (100%). Statistical analysis based on confidence interval revealed a prediction error between −1.62% and −3.05% for manual slack adjuster and 0.43% and −1.62% for automatic slack adjuster for 99% confidence interval, which demonstrated the efficacy of the proposed prediction scheme.

scholarly journals Research on Dynamic Reliability of a Jet Pipe Servo Valve Based on Generalized Stochastic Petri Nets

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yuanbo Chu ◽  
Zhaohui Yuan ◽  
Jia Chen
Keyword(s):  
Petri Nets ◽  
Failure Rate ◽  
Failure Modes ◽  
Stochastic Petri Nets ◽  
Rate Data ◽  
Repair Rate ◽  
Dynamic Reliability ◽  
Servo Valve ◽  
Reliability Parameters ◽  
Generalized Stochastic Petri Nets

The jet pipe servo valve is widely used in the military fields of aviation and ship, whose reliability has obvious randomness and dynamic. However, existing methods are either having complicated theory or analyzing static reliability. Based on the generalized stochastic petri nets (GSPN) theory and the collected basic failure modes and failure rate data of jet pipe servo valve, this paper proposes a novel modeling and simulating method for system’s dynamic behavior analysis. In this method, the dynamic reliability model considering failure’s random and repair is established and is simulated using GSPN software. Then, the steady state probability of servo valve is calculated, which is compared with the value calculated by Markov method. Finally, the dynamic reliability parameters of jet pipe servo valve are calculated using collected failure rate data and different repair rate data. Results show the probability that the maximum error between methods of GSPN and Markov is 2.07%, the optimal repair rate set is less than 1.71µi, and also the dynamic reliability parameters become better with increasing simulation time because of failure’s recovery. Therefore, research methods and results based on GSPN are concise and realistic, which can be used for failure’s qualitative forecast and dynamic reliability’s quantitative calculation of similar complicated system.

scholarly journals Research on the Dynamic Erosion Wear Characteristics of a Nozzle Flapper Pressure Servo Valve Used in Aircraft Brake System

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yuanbo Chu ◽  
Zhaohui Yuan ◽  
Wenchao Chang
Keyword(s):  
Service Life ◽  
Life Prediction ◽  
Wear Behavior ◽  
Prediction Method ◽  
Service Life Prediction ◽  
Dynamics Simulation ◽  
Brake System ◽  
Erosion Wear ◽  
Wear Characteristics ◽  
Servo Valve

The nozzle flapper pressure servo valve is a kind of high-precision hydraulic component that can be widely used in the aircraft brake system. In actual service, the dynamic erosion wear behavior will occur at the pilot stage because of the gradual contamination of oil and the variable distance between nozzle and flapper. For this purpose, the paper proposes a dynamic erosion wear characteristics analysis and service life prediction method in which firstly the structural feature and working principle of the nozzle flapper pressure valve are analyzed using the brake cavity as the load blind cavity. Secondly, the dynamics simulation model and the performance experiment system of the pressure valve are separately constructed, and then the validation of the constructed model is conducted by contrasting the results between simulation and experiment. Finally, the mathematical models of the degradation process induced by the dynamic erosion wear are established, and then the dynamic erosion wear characteristics under dynamic structural distance and contamination conditions are analyzed, which are combined with the failure threshold value determined by the dynamics simulation to finish the service life prediction of the nozzle flapper pressure servo valve.

Effect of Pressure on Dry and Hydrated Self Assembled Monolayers: A Molecular Dynamics Simulation Study

2014 ◽  
Vol 553 ◽  
pp. 35-40
Author(s):  
Leyla Ramin ◽  
Ahmad Jabbarzadeh
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
High Pressures ◽  
Elastic Recovery ◽  
Structural Characteristics ◽  
Dynamics Simulation ◽  
Self Assembled Monolayers ◽  
Effect Of Pressure ◽  
Assembled Monolayers ◽  
Self Assembled

Molecular dynamics simulation was used to study the effect of pressure on self-assembled monolayers (SAM) of n-alkanethiols [(CH3(CH2) n-1, n=14, 15] on Au (111) for dry systems and in the presence of water. The stress-strain behavior and effects of compression on structural characteristics under various normal pressures have been investigated. We found the effect of compression on tilt and tilt orientation angles for dry and hydrated SAM system. Furthermore, a comparison of the results obtained for tilt and tilt orientation angles for hydrated C14 and C15 indicates a more stable structure for C15 (an odd system) under high pressures. We also found excellent elastic recovery of SAM monolayers with and without water is evidence of their exceptional potential to be used under compression in various conditions. Young’s moduli are calculated for various systems under uniaxial compression.

Dynamic Characteristics Analysis for Seismic Vibrator

2014 ◽  
Vol 472 ◽  
pp. 48-55
Author(s):  
Li Qiang An ◽  
Fan Peng Kong ◽  
Yong Fang Wang
Keyword(s):  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Data Transfer ◽  
Element Model ◽  
Dynamics Simulation ◽  
Characteristic Analysis ◽  
Characteristics Analysis ◽  
Stiffness And Damping ◽  
Multi Body ◽  
Seismic Vibrator

Seismic vibrator is one of the most widely used equipments in exploration field. In recent years, with the development of exploration field, as well as the growing needs of high quality seismic data, the seismic vibrator's tonnage has increased a lot, which makes the stress of the vehicle frame very complicated in working state. And some local structure of the vehicle frame often appears crack phenomenon in working state. Therefore, the dynamic characteristic analysis is essential to the Seismic vibrator. In this paper, the finite element model of vehicle frame is established by ANSYS software. Through the modal analysis, the natural frequencies are obtained, and each vibration modes are analyzed. On the basis of the modal analysis, the modal neutral file of the vehicle frame is established. Using the data transfer function between ANSYS and ADAMS, the rigid-flexible coupling multi-body model is built for the dynamics simulation of the seismic vibrator. In this model, the stiffness and damping of air springs, hydraulic oil and soil are simulated by the spring-damper in the ADAMS software. The dynamic characteristics of vehicle frame under excited forces with different amplitude are obtained and analyzed. The stresses for some of the hot spots of the vehicle frame are extracted, which can be used to analyze the dynamic failure of the vehicle frame.

scholarly journals Influence of Adhesion Properties on the Crash Behavior of Steel/Polymer/Steel Sandwich Crashboxes: An Experimental Study

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1400 ◽  
Author(s):  
Mohamed Harhash ◽  
Moritz Kuhtz ◽  
Jonas Richter ◽  
Andreas Hornig ◽  
Maik Gude ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Failure Modes ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Failure Behavior ◽  
Adhesion Properties ◽  
Polymer Adhesion ◽  
Strong Adhesion ◽  
Materials Used ◽  
The Impact

The energy absorption behavior of crashboxes made of steel/polymer/steel (SPS) sandwich sheets can be influenced by numerous parameters, such as the materials used, their thicknesses and stacking, and the adhesion properties between their layers. Therefore, in the present study, the impact of steel/polymer adhesion quality on the occurring failure modes of the crashboxes and the resulting energy absorptions are experimentally analyzed. For this purpose, axial crushing and three-point bending tests on double-hat and top-hat crash boxes were performed, respectively. Three levels of adhesion quality are investigated: none, weak, and strong adhesion strengths. Additionally, the structural crash properties, such as energy absorption and maximal intrusion, are determined and analyzed at both of the quasi-static and highly dynamic loading rates. The results of these investigations show that the adhesion strengths chosen here significantly influence both the failure modes and the energy absorption values. In particular, the structural parameters, in the case of no adhesion, are at most half of those in the case of strong adhesion. However, it is also shown that, in the case of weak adhesion, the structural characteristics are slightly reduced. Based on these results, the possibility to adjust the adhesion strength—globally and/or locally—could be used in future activities to purposefully tailor the failure behavior of hybrid crashboxes.

Sign in / Sign up

Export Citation Format

Share Document