scholarly journals A Nonsmooth Quasistatic Modeling Approach for Hydraulic Actuators

2021 ◽  
Author(s):  
Ryo Kikuuwe ◽  
Tomofumi Okada ◽  
Hideo Yoshihara ◽  
Takayuki Doi ◽  
Takao Nanjo ◽  
...  
Keyword(s):  
Steady State ◽  
Analytical Approach ◽  
Hydraulic Actuators ◽  
Modeling Approach ◽  
Multiple Actuators ◽  
State Force ◽  
Analytical Expressions ◽  
State Pressure ◽  
Electric Analogy

Abstract This paper presents an analytical approach for modeling the quasistatic characteristics of hydraulic actuators driven by four-valve independent metering circuits. The presented model is described as a nonsmooth, set-valued function from the velocity to the set of forces with which the equilibrium is achieved at the velocity. It is derived from algebraic relations among the velocity of the actuator, the steady-state force generated by the actuator, and the flowrate and the steady-state pressure at all valves in the circuit. This approach is also applied to more involving circuits including a regeneration pipeline and those with multiple actuators. The contribution of the paper can be seen as an example case study of the fact that these complicated circuit structures are analytically tractable through an extension of the conventional hydraulic-electric analogy. The obtained analytical expressions of the steady-state velocity-force relations allow for concise visualization of the actuators' characteristics.

scholarly journals Lifetime Benefit Analysis of Intelligent Maintenance: Simulation Modeling Approach and Industrial Case Study

2021 ◽  
Vol 11 (8) ◽  
pp. 3487
Author(s):  
Helge Nordal ◽  
Idriss El-Thalji
Keyword(s):  
Simulation Model ◽  
Simulation Modeling ◽  
Study Data ◽  
Opportunistic Maintenance ◽  
Maintenance Strategies ◽  
Modeling Approach ◽  
Intelligent Maintenance ◽  
Diagnosis And Prognosis ◽  
Case Study Data

The introduction of Industry 4.0 is expected to revolutionize current maintenance practices by reaching new levels of predictive (detection, diagnosis, and prognosis processes) and prescriptive maintenance analytics. In general, the new maintenance paradigms (predictive and prescriptive) are often difficult to justify because of their multiple inherent trade-offs and hidden systems causalities. The prediction models, in the literature, can be considered as a “black box” that is missing the links between input data, analysis, and final predictions, which makes the industrial adaptability to such models almost impossible. It is also missing enable modeling deterioration based on loading, or considering technical specifications related to detection, diagnosis, and prognosis, which are all decisive for intelligent maintenance purposes. The purpose and scientific contribution of this paper is to present a novel simulation model that enables estimating the lifetime benefits of an industrial asset when an intelligent maintenance management system is utilized as mixed maintenance strategies and the predictive maintenance (PdM) is leveraged into opportunistic intervals. The multi-method simulation modeling approach combining agent-based modeling with system dynamics is applied with a purposefully selected case study to conceptualize and validate the simulation model. Three maintenance strategies (preventive, corrective, and intelligent) and five different scenarios (case study data, manipulated case study data, offshore and onshore reliability data handbook (OREDA) database, physics-based data, and hybrid) are modeled and simulated for a time period of 20 years (175,200 h). Intelligent maintenance is defined as PdM leveraged in opportunistic maintenance intervals. The results clearly demonstrate the possible lifetime benefits of implementing an intelligent maintenance system into the case study as it enhanced the operational availability by 0.268% and reduced corrective maintenance workload by 459 h or 11%. The multi-method simulation model leverages and shows the effect of the physics-based data (deterioration curves), loading profiles, and detection and prediction levels. It is concluded that implementing intelligent maintenance without an effective predictive horizon of the associated PdM and effective frequency of opportunistic maintenance intervals, does not guarantee the gain of its lifetime benefits. Moreover, the case study maintenance data shall be collected in a complete (no missing data) and more accurate manner (use hours instead of date only) and used to continuously upgrade the failure rates and maintenance times.

Comparison of Numerical Methods for Determining Torsion Stiffness of Automotive Chassis

2011 ◽  
Author(s):  
Steven Tebby ◽  
Ebrahim Esmailzadeh ◽  
Ahmad Barari
Keyword(s):  
Finite Element Analysis ◽  
Analytical Approach ◽  
Torsional Stiffness ◽  
Design Stage ◽  
Element Analysis ◽  
Detailed Design ◽  
Vertical Displacements ◽  
Comparison Of The Results ◽  
Torsion Stiffness

The torsion stiffness of an automotive chassis can be determined using an analytical approach based purely on geometry, using an experimental method, or alternatively by employing a Finite Element Analysis (FEA) process. These three methods are suitable at different design stages and combined together could prove to be practical methods of determining the torsion stiffness of a chassis. This paper describes and compares two distinct FEA processes to determine the torsion stiffness of an automotive chassis during the detailed design stage. The first process iteratively applies forces to the model and records displacements, while the second process gradually applies vertical displacements in place of force to determine the torsional stiffness threshold. Each method is explained and supported with a case study to provide a basis of comparison of the results.

scholarly journals Modeling non-steady state radioisotope transport in the vadose zone – A case study using uranium isotopes at Peña Blanca, Mexico

2009 ◽  
Vol 73 (20) ◽  
pp. 6052-6064 ◽  
Author(s):  
T.L. Ku ◽  
S. Luo ◽  
S.J. Goldstein ◽  
M.T. Murrell ◽  
W.L. Chu ◽  
...  
Keyword(s):  
Steady State ◽  
Vadose Zone ◽  
Uranium Isotopes

Encoding of amplitude and rate of forces applied to the teeth by human periodontal mechanoreceptive afferents

1994 ◽  
Vol 72 (4) ◽  
pp. 1734-1744 ◽  
Author(s):  
M. Trulsson ◽  
R. S. Johansson
Keyword(s):  
Steady State ◽  
Discharge Rate ◽  
Inferior Alveolar Nerve ◽  
Steady State Response ◽  
Force Amplitude ◽  
Stimulus Response ◽  
State Response ◽  
Dynamic Sensitivity ◽  
Linear Relationships ◽  
State Force

1. The encoding of force amplitude and force rate by human periodontal mechanoreceptive afferents was studied. Recordings were obtained from 19 single periodontal afferents in the inferior alveolar nerve with the use of tungsten microelectrodes. Loads consisting of a force increase (loading ramp), a phase of maintained force (static phase), and a force decrease (unloading ramp) were applied to the receptor bearing tooth, which was most often an incisor. The static forces applied ranged between 0.05 and 5 N, and the rate of force applied during the loading ramps ranged between 0.4 and 70 N/s. The forces were primarily applied in one of six directions (lingual, labial, mesial, distal, upward, or downward) that evoked the greatest discharge activity. 2. For each force application, the steady-state response was defined as the mean discharge rate during a 1-s period starting 0.5 s after the end of the loading ramp. Most afferents (15/19) exhibited a “hyperbolic” (viz., negatively accelerating) relationship between the amplitude of the stimulation force and the steady-state response, featuring a pronounced saturation tendency: the highest sensitivity to changes in static force was observed at force levels below 1 N. At higher force levels the sensitivity gradually diminished. Moreover, the dynamic sensitivity similarly decreased with increasing amplitude of static background force. For a subsample of afferents studied, comparable stimulus-response relationships were obtained in directions other than the most responsive one, but the discharge rates were lower. 3. In contrast to the response of most afferents, four (4/19) differed in that they consistently exhibited a nearly linear relationship between force amplitude and the steady-state response. Moreover, these afferents maintained their dynamic sensitivity as the amplitude of the background force was increased. 4. The steady-state response of all afferents was well described as a constant times F/ (F + c), where F represents the steady-state force, and c the force generating one-half the estimated maximum discharge rate that could be evoked by steady-state force stimulation. The c-parameter was on average 0.42 N (range 0.05–1.1 N) for the afferents exhibiting hyperbolic stimulus-response relationships. In contrast it ranged between 5 and 22 N for those exhibiting “nearly linear” relationships. A hypothetical model of the mechanics of the periodontal ligament supporting the F/(F + c) transform is proposed. 5. A general transfer function was developed to predict the instantaneous discharge rate of an individual afferent to arbitrary force profiles applied to the receptor bearing tooth.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document