Analysis of assembly defects in the cam curved groove mechanism

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Weibin Lan ◽  
Shouwen Fan ◽  
Shuai Fan
Keyword(s):  
Dynamic Characteristics ◽  
Contact Point ◽  
Contact Theory ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Interference Fit ◽  
Content Type ◽  
Cam Mechanism ◽  
Contact Points ◽  
General Mathematical Model

Purpose This paper aims to propose an elementary approach toward the identification of assembly defects of a cam curved groove mechanism. Design/methodology/approach A numerical analysis method for identifying the assembly defects of the cam curved groove mechanism is proposed by resorting to Hertz contact theory. A general mathematical model is established to analyze the kinematic and dynamic characteristics with an interference fit between the main roller and cam curved groove, including the contact points of the external and internal ring. Findings The analysis method of the contact point characteristics of the cam curved groove mechanism is given in this paper, and the kinematic and dynamic characteristics of the main roller can be analyzed. The numerical examples presented in this paper are implemented in MATLAB, feasibility and validity of the above algorithm are verified by the finite element method. Originality/value Regarding the defects of the interference fit, the findings of this paper can serve as a reference for researchers in reducing the defects in the design process of the cam mechanism.

In-plane dynamic response of a hydraulic pipe subjected to random vibration

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wei Qu ◽  
Huailiang Zhang ◽  
Wei Li ◽  
Ling Peng ◽  
Wenqian Sun
Keyword(s):  
Random Vibration ◽  
Tunnel Boring Machine ◽  
Transmission Efficiency ◽  
Hydraulic Systems ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Characteristic Analysis ◽  
Content Type ◽  
Tunnel Boring ◽  
Selection Of

Purpose To improve the transmission efficiency and reduce the damage to pipes in the hydraulic systems of tunnel boring machine subjected to random vibration, this paper aims to propose a novel dynamic characteristic analysis method that considers random vibration. Design/methodology/approach A fluid-structure interaction motion equation of the pipe is established by using Hamilton’s principle. The finite element method and discrete analysis method of random vibration are used to construct a model of the dynamic behavior of the pipe. Findings The influences of fluid parameters and external excitation parameters on the dynamic characteristics of pipes are analyzed. The experimental results are found to be in good agreement with the simulation results, which demonstrates that the proposed analytical method can provide a theoretical reference for the design and selection of hydraulic pipes subjected to random vibration. Originality/value The proposed method can be regarded as a future calculation method for pipes subjected to random vibration, and the transmission efficiency of the pipe can be improved.

scholarly journals Analysis of Contact Deformations in Support Systems Using Roller Prisms

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2644
Author(s):  
Krzysztof Nozdrzykowski ◽  
Zenon Grządziel ◽  
Paweł Dunaj
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Theory ◽  
Finite Element Analyses ◽  
The Finite Element Method ◽  
Hertz Contact ◽  
Contact Points ◽  
Calculation Results ◽  
Reaction Forces ◽  
Shaft Journal

This article presents the results of finite element analyses of the influence of reaction forces on stresses and strains at the contact points of the rollers of prism supports with cylindrical surfaces of the main journals of large-sized crankshafts. The analyses of strains and stresses, as well as the depth of their occurrences, in the case of the shaft journal and support rollers were carried out using Hertz contact theory and the finite element method. These calculation results proved to be highly consistent. Additionally, they provide a basis for stating that, in the case under consideration, permanent deformations do not significantly affect the values of the measured geometrical deviations nor the profile forms of the supported main crankshaft journals.

Three‐dimensional discrete element simulation for granular materials

2006 ◽  
Vol 23 (7) ◽  
pp. 749-770 ◽  
Author(s):  
Dawei Zhao ◽  
Erfan G. Nezami ◽  
Youssef M.A. Hashash ◽  
Jamshid Ghaboussi
Keyword(s):  
Search Algorithm ◽  
Contact Point ◽  
Three Dimensional ◽  
Engineering Application ◽  
Discrete Element ◽  
Content Type ◽  
Polyhedral Particles ◽  
Contact Points ◽  
Neighbor Search ◽  
Force Calculation

PurposeDevelop a new three‐dimensional discrete element code (BLOKS3D) for efficient simulation of polyhedral particles of any size. The paper describes efficient algorithms for the most important ingredients of a discrete element code.Design/methodology/approachNew algorithms are presented for contact resolution and detection (including neighbor search and contact detection sections), contact point and force detection, and contact damping. In contact resolution and detection, a new neighbor search algorithm called TLS is described. Each contact is modeled with multiple contact points. A non‐linear force‐displacement relationship is suggested for contact force calculation and a dual‐criterion is employed for contact damping. The performance of the algorithm is compared to those currently available in the literature.FindingsThe algorithms are proven to significantly improve the analysis speed. A series of examples are presented to demonstrate and evaluate the performance of the proposed algorithms and the overall discrete element method (DEM) code.Originality/valueLong computational times required to simulate large numbers of particles have been a major hindering factor in extensive application of DEM in many engineering applications. This paper describes an effort to enhance the available algorithms and further the engineering application of DEM.

Influence of micro-scale velocity slip on the dynamic characteristics of aerostatic slider

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dongju Chen ◽  
Shuai Kong ◽  
Jingfang Liu ◽  
Jinwei Fan
Keyword(s):  
Peer Review ◽  
Dynamic Characteristics ◽  
Velocity Slip ◽  
Analysis Method ◽  
Element Analysis ◽  
Fluid Equation ◽  
Content Type ◽  
First Order ◽  
Static Performance ◽  
Simulation And Experiment

Purpose The purpose of this paper is to propose the pressure fluctuation to further evaluate and predict the dynamic and static characteristics of the aerostatic slider and improve the calculation accuracy of the aerostatic slider. Design/methodology/approach First-order velocity slip is introduced into the traditional gas-film fluid equation, and the numerical analysis method is used to solve the static performance of the aerostatic slider. The finite element analysis method is used to solve its dynamic characteristics. Findings It can be concluded from the simulation and experimental results that the model considering the velocity slip in the gas film flow is more accurate. The errors between the modal detection results and the vibration detection results (0.8%–5.8%) under speed slip are smaller than the traditional cases (23.7%–210%), which also verifies the correctness of the above conclusions. Originality/value In this paper, the method of simulation and experiment is used to prove that the first-order velocity slip model is more suitable to predict the dynamic response of the aerostatic slider than the condition without slip. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2020-0059/

Analysis of dynamic characteristics of spiral groove liquid film seal considering cavitation

2018 ◽  
Vol 70 (9) ◽  
pp. 1619-1629 ◽  
Author(s):  
Mu-ming Hao ◽  
Wen-jing Yang ◽  
Heng-chao Cao ◽  
Lu-shuai Xu ◽  
Yun-lei Wang ◽  
...  
Keyword(s):  
Liquid Film ◽  
Dynamic Characteristics ◽  
Design Method ◽  
Mechanical Seals ◽  
The Finite Element Method ◽  
Spiral Groove ◽  
Film Rupture ◽  
Content Type ◽  
Infinitesimal Perturbation ◽  
The Difference

Purpose The purpose of this paper is to investigate the dynamic characteristics of a spiral groove liquid film seal considering the effect of cavitation. Design/methodology/approach A mathematical model of a spiral groove liquid film seal was established based on the mass-conserving Jakobsson–Floberg–Olsson cavitation boundary condition. The film rupture and film reformation boundaries were assumed to be unchanged under infinitesimal perturbation conditions. Governing equations under steady and perturbed states were solved by the finite element method, and then the dynamic characteristics of the spiral groove liquid film seal were theoretically investigated considering the effect of cavitation. Findings The results indicate that dynamic coefficients considering cavitation are smaller than those neglecting cavitation. The difference value is consistent with the change in cavitation area. The liquid film seal does not suffer axial instability whether considering cavitation, but its angular instability is more likely to occur when cavitation is considered. Originality/value For liquid lubricated non-contacting mechanical seals, the dynamic characteristics considering cavitation are investigated. The results are expected to provide a theoretical basis for improving the design method of liquid film seals.

scholarly journals Slipping–rolling transitions of a body with two contact points

2021 ◽  
Author(s):  
Mate Antali ◽  
Gabor Stepan
Keyword(s):  
Rigid Body ◽  
Contact Point ◽  
Static Friction ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Friction Forces ◽  
Contact Points ◽  
Body Dynamics ◽  
Coulomb Model ◽  
Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

scholarly journals Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

2021 ◽  
pp. 146808742110080
Author(s):  
Jamshid Malekmohammadi Nouri ◽  
Ioannis Vasilakos ◽  
Youyou Yan
Keyword(s):  
High Speed ◽  
Contact Point ◽  
Cylinder Liner ◽  
Optical Methods ◽  
Engine Management System ◽  
Great Success ◽  
Ic Engine ◽  
Contact Points ◽  
Lubricant Flow ◽  
Cavitation Intensity

A new engine block with optical access has been designed and manufactured capable of running up to 3000 r/min with the same specification as the unmodified engine. The optical window allowed access to the full length of the liner over a width of 25 mm to investigate the lubricant flow and cavitation at contact point between the rings and cylinder-liner. In addition, it allowed good access into the combustion chamber to allow charged flow, spray and combustion visualisation and measurements using different optical methods. New custom engine management system with build in LabView allowed for the precise full control of the engine. The design of the new optical engine was a great success in producing high quality images of lubricant flow, cavitation formation and development at contact point at different engine speeds ranging from 208 to 3000 r/min and lubricant temperatures (30°C–70°C) using a high-speed camera. The results under motorised operation confirmed that there was no cavitation at contact points during the intake/exhaust strokes due to low in-cylinder presure, while during compression/expansion strokes, with high in-cylinder pressure, considerable cavities were observed, in particular, during the compression stroke. Lubricant temperatures had the effect of promoting cavities both in their intensity and covered ring area up to 50°C as expected. Beyond that, although the cavitation intensity increases further with temperature, its area reduces due to possible collapse of the cavitating bubbles at higher temperature. The change of engine speed from 208 to 800 r/min increased cavitating area considerably by 52% of the ring area and was further increased by 19% at 1000 r/min. After that, the results showed very small increase in cavitation area (1.3% at 2000 r/min) with similar intensity and distribution across the ring.

scholarly journals Simulative investigation of ring creep on a planetary bearing of a wind turbine gearbox

2021 ◽  
Author(s):  
Jonas Gnauert ◽  
Felix Schlüter ◽  
Georg Jacobs ◽  
Dennis Bosse ◽  
Stefan Witter
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Sensitivity Analysis ◽  
Planetary Gear ◽  
The Finite Element Method ◽  
Relative Movement ◽  
Wind Turbine Gearbox ◽  
Interference Fit ◽  
Planetary Gears ◽  
Module Coefficient

AbstractWind turbines (WT) must be further optimized concerning availability and reliability. One of the major reasons of WT downtime is the failure of gearbox bearings. Some of these failures occur, due to the ring creep phenomenon, which is mostly detected in the planetary bearings. The ring creep phenomenon describes a relative movement of the outer ring to the planetary gear. In order to improve the understanding of ring creep, the finite element method (FEM) is used to simulate ring creep in planetary gears. First, a sensitivity analysis is carried out on a small bearing size (NU205), to characterize relevant influence parameters for ring creep—considered parameters are teeth module, coefficient of friction, interference fit and normal tooth forces. Secondly, a full-scale planetary bearing (SL185030) of a 1MW WT is simulated and verified with experimental data.

The “Halalification” of tourism

2017 ◽  
Vol 8 (4) ◽  
pp. 558-577 ◽  
Author(s):  
Faiza Khan ◽  
Michelle Callanan
Keyword(s):  
Design Methodology ◽  
Secondary Data ◽  
Market Segment ◽  
Analysis Method ◽  
Review Of Literature ◽  
Primary Research ◽  
Content Type ◽  
Starting Point ◽  
Practical Implications

Purpose The purpose of this paper is to address the confusing use of terminology associated with tourism undertaken by Muslims and to identify key concerns associated with this type of tourism. Design/methodology/approach This is an exploratory study and adopts a critical review of literature following the evolutionary concept analysis method. Content analysis of popular UK media, UK-based tour operators’ websites and tourism strategies of destinations popular with Muslim tourists were conducted to examine the use of terminology. Findings There is no clear difference between the various terms (halal, Muslim friendly, Islamic, etc.) used. Overall, academia uses the term Islamic tourism, while the industry and media use various terms. Among destinations, however, there is no clear and consistent use of terminology. A key concern of Islamic tourism is the role of certification in assuring travellers and the lack of standardisation of halal certification. Research limitations/implications The paper is based on literature review and secondary data analysis. It lacks primary research. Practical implications This study highlights the need for consistent use of terminology across industry. Another implication is the issue surrounding halal certification of food and the importance of trust in the seller/service provide. Another trend that industry providers need to consider is the growth of the Muslim millennial traveller and the needs of this market segment. Originality/value The paper highlights the importance of studying the Muslim tourist market and provides a starting point for further research. It highlights several issues such as the need to develop a typology of Muslim tourists. Of particular interest is the concern whether halal values in danger of being commodified in the absence of a universal agreed criterion for halal certification.

P-24: The Analysis Method of Dynamic Characteristics in LCD

2003 ◽  
Vol 34 (1) ◽  
pp. 292
Author(s):  
Don-Gyou Lee ◽  
Seung-chul Park ◽  
Ki-Bok Park ◽  
Kyeong-Jin Kim ◽  
Moon Cheol Jeong ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Analysis Method
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