scholarly journals On the Nonlinear Response of a Flexible Connecting Rod

2003 ◽  
Vol 125 (4) ◽  
pp. 757-763 ◽  
Author(s):  
Jen-San Chen ◽  
Chu-Hsian Chian
Keyword(s):  
Dynamic Response ◽  
Mechanical Design ◽  
Nonlinear Finite Element ◽  
Nonlinear Finite Element Method ◽  
Connecting Rod ◽  
Lagrangian Strain ◽  
Order Of Magnitude ◽  
Asme Journal ◽  
Parametric And External Excitations

In two recent papers (Chen, J.-S., and Chen, K.-L., 2001, “The Role of Lagrangian Strain in the Dynamic Response of a Flexible Connecting Rod,” ASME Journal of Mechanical Design, 123, pp. 542–548; Chen, J.-S., and Huang, C.-L., 2001, “Dynamic Analysis of Flexible Slider-Crank Mechanisms With Nonlinear Finite Element Method,” Journal of Sound and Vibration, 246, pp. 389–402) we reported that previous researches of others on the dynamic response of a flexible connecting rod may have overestimated the deflections by ten folds when the crank rotates near the bending natural frequency of the connecting rod because terms of significant order of magnitude were ignored inadequately. While the findings in (Chen, J.-S., and Chen, K.-L., 2001, “The Role of Lagrangian Strain in the Dynamic Response of a Flexible Connecting Rod,” ASME Journal of Mechanical Design, 123, pp. 542–548; Chen, J.-S., and Huang, C.-L., 2001, “Dynamic Analysis of Flexible Slider-Crank Mechanisms With Nonlinear Finite Element Method,” Journal of Sound and Vibration, 246, pp. 389–402.) were obtained via numerical simulations, the present paper emphasizes the analytical approach with an aim to exploring the physical insights behind these numerical results. The equations of motion are first derived by applying Hamilton’s principle with all high order terms in the strain energy function being retained. After careful examination of the order of magnitude of each term, the coupled equations are simplified to a single one in terms of the transverse deflection, which turns out to be a Duffing equation under parametric and external excitations simultaneously. Closed-form approximations of the dynamic response are then derived by using multiple scale method. It is found that the combined effects of parametric and external excitations dominate the response when Ω is close to 0.5 and 1. Away from these two speed ranges, on the other hand, the response is dominated by the external excitation alone.

scholarly journals The Role of Lagrangian Strain in the Dynamic Response of a Flexible Connecting Rod

1999 ◽  
Vol 123 (4) ◽  
pp. 542-548 ◽  
Author(s):  
Jen-San Chen ◽  
Kwin-Lin Chen
Keyword(s):  
Dynamic Response ◽  
Axial Load ◽  
Slenderness Ratio ◽  
Equations Of Motion ◽  
Transverse Displacement ◽  
Linear Strain ◽  
Connecting Rod ◽  
Lagrangian Strain ◽  
Order Of Magnitude

Previous researches on the dynamic response of a flexible connecting rod can be categorized by the ways the axial load in the rod is being formulated. The axial load may be assumed to be (1) dependent only on time and can be obtained by treating the rod as rigid, (2) related to the transverse displacement by integrating the axial equilibrium equation, and (3) proportional to linear strain. This paper examines the validity of these formulations by first deriving the equations of motion assuming the axial load to be proportional to the Lagrangian strain. In order for the dimensionless displacements to be in the order of O(1), different nondimensionalization schemes have to be adopted for low and high crank speeds. The slenderness ratio of the connecting rod arises naturally as a small parameter with which the order of magnitude of each term in the equations of motion, and the implication of these simplified formulations can be examined. It is found that the formulations in previous researches give satisfactory results only when the crank speed is low. On the other hand when the crank speed is comparable to the first bending natural frequency of the connecting rod, these simplified formulations overestimate considerably the dynamic response because terms of significant order of magnitude are removed inadequately.

Dynamics of a Multibody Mechanical System With Lubricated Long Journal Bearings

2004 ◽  
Vol 127 (3) ◽  
pp. 493-498 ◽  
Author(s):  
B. J. Alshaer ◽  
H. Nagarajan ◽  
H. K. Beheshti ◽  
H. M. Lankarani ◽  
S. Shivaswamy
Keyword(s):  
Dynamic Response ◽  
Mechanical System ◽  
Journal Bearing ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Journal Bearings ◽  
Connecting Rod ◽  
Revolute Joint ◽  
Order Of Magnitude

Clearances exist in different kinds of joints in multibody mechanical systems, which could drastically affect the dynamic behavior of the system. If the joint is dry with no lubricant, impact occurs, resulting in wear and tear of the joint. In practical engineering design of machines, joints are usually designed to operate with some lubricant. Lubricated journal bearings are designed so that even when the maximum load is applied, the joint surfaces do not come into contact with each other. In this paper, a general methodology for modeling lubricated long journal bearings in multibody mechanical systems is presented. This modeling utilizes a method of solving for the forces produced by the lubricant in a dynamically loaded long journal bearing. A perfect revolute joint in a multibody mechanical system imposes kinematic constraints, while a lubricated journal bearing joint imposes force constraints. As an application, the dynamic response of a slider-crank mechanism including a lubricated journal bearing joint between the connecting rod and the slider is considered and analyzed. The dynamic response is obtained by numerically solving the constraint equations and the forces produced by the lubricant simultaneously with the differential equations of motion and a set of initial conditions numerically. The results are compared with the previous studies performed on the same mechanism as well a dry clearance joint. It is shown that in a multibody mechanical system, the journal bearing lubricant introduces damping and stiffness to the system. The earlier studies predict that the order of magnitude of the reaction moment is twice that of a perfect revolute joint. The proposed model predicts that the reaction moment is within the same order of magnitude of the perfect joint simulation case.

Dynamics of a Multibody Mechanical System With Lubricated Long Journal Bearings

2001 ◽  
Author(s):  
B. J. Alshaer ◽  
H. M. Lankarani ◽  
S. Shivaswamy
Keyword(s):  
Dynamic Response ◽  
Mechanical System ◽  
Journal Bearing ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Journal Bearings ◽  
Connecting Rod ◽  
Revolute Joint ◽  
Order Of Magnitude

Abstract Clearances exist in different kinds of joints in multibody mechanical systems, which could drastically affect the dynamic behavior of the system. If the joint is dry with no lubricant, impact occurs, resulting in wear and tear of the joint. In practical engineering design of machines, joints are usually designed to operate with some lubricant. Lubricated journal bearings are designed so that even when the maximum load is applied, the joint surfaces do not come into contact with each other. In this paper, a general methodology for modeling lubricated long journal bearings in multibody mechanical systems is presented. This modeling utilizes a new method of solving for the forces produced by the lubricant in a dynamically loaded long journal bearing. A perfect revolute joint in a multibody mechanical system imposes kinematic constraints, while a lubricated journal bearing joint imposes force constraints. As an application, the dynamic response of a crank-slider mechanism including a lubricated journal bearing joint between the connecting rod and the slider is considered and analyzed. The dynamic response is obtained by numerically solving the constraint equations and the forces produced by the lubricant simultaneously with the differential equations of motion and a set of initial conditions numerically. The results are compared with the previous studies performed on the same mechanism as well a dry clearance joint. It is shown that in a multibody mechanical system, the journal bearing lubricant introduces damping and stiffness to the system. The earlier studies previous predict that the order of magnitude of the reaction moment is twice that of a perfect revolute joint. The proposed model predicts that the reaction moment is within the same order of magnitude of the perfect joint simulation case.

Dynamic Response Research of VLEC’s Cargo Containment System under Sloshing Impact Load

2015 ◽  
Author(s):  
Gu Jinlan ◽  
Li Xiaoling ◽  
Qin Bin ◽  
Gu Yunfei
Keyword(s):  
Finite Element Method ◽  
Dynamic Response ◽  
Static Pressure ◽  
Impact Load ◽  
Nonlinear Finite Element ◽  
Critical Area ◽  
Nonlinear Finite Element Method ◽  
Membrane Type ◽  
Cfd Method ◽  
Tank Sloshing

Membrane type CCS is one of the most possible solutions for VLEC. As static pressure and sloshing impact load will increase due to higher density, this result in the question of whether VLEC’s CCS is strong enough to withstand the increased load in the critical area. In this paper, ultimate strength of CCS in different boundary conditions was investigated using nonlinear finite element method. The dynamic response of CCS under critical sloshing impact load cases selected from tank sloshing analysis results using CFD method was investigated. Some important insights obtained from the study were summarized.

The Role of Compliance in the Design of MEMS

1996 ◽  
Author(s):  
G. K. Ananthasuresh ◽  
Sridhar Kota
Keyword(s):  
Mechanical Design ◽  
Relevant Literature ◽  
Flexible Structures ◽  
Mechanical Systems ◽  
Great Majority ◽  
Micro Electro Mechanical Systems

Abstract A great majority of the available micro devices and systems use compliant (or flexible) structures and mechanisms. This trend in design takes advantage of micromachining techniques while satisfying the constraints imposed by them. By citing relevant literature, this article briefly notes the influence of compliance on the mechanical design and analysis of Micro-Electro-Mechanical Systems (MEMS).

Seismic Time-History Analysis of Gravity Dam Based on Nonlinear Finite Element Method

2013 ◽  
Vol 351-352 ◽  
pp. 1047-1051
Author(s):  
He Zhu ◽  
Gang Wang ◽  
Zhen Yue Ma ◽  
Yi Kang Su
Keyword(s):  
Time History ◽  
Nonlinear Finite Element ◽  
Gravity Dam ◽  
Elastic Model ◽  
Nonlinear Finite Element Method ◽  
Initial Stiffness ◽  
Cohesive Model ◽  
Damage Initiation ◽  
History Analysis ◽  
Constitutive Response

A cohesive model (CM) was introduced in this paper. The constitutive response of cohesive behavior depends on a traction-separation description characterized by the initial stiffness, damage initiation threshold, and damage evolution properties.Through the aseismic analysis of a gravity dam, the displacement, stress and anti-sliding safety factor were discussed in the paper, the results were also compared between elastic model (EM) and plastic model (PM). The results shown that the displacement amplitude computed by PM and CM was nearly twice larger than that by EM, and the area of stress concentration became not so obvious. The cohesive model could efficiently simulate the discontinuous structure and the responses of seismic computed by PM and CM were more correspond to actual situation.

Study on Antiseismic Measures of Tailings Dam

2011 ◽  
Vol 90-93 ◽  
pp. 44-47
Author(s):  
Jian Ping Pan ◽  
Sheng Yi Wang ◽  
Shui Tai Xu
Keyword(s):  
Finite Element Method ◽  
Rock Pressure ◽  
Deformation Characteristic ◽  
Nonlinear Finite Element ◽  
Stone Column ◽  
Tailings Dam ◽  
Nonlinear Finite Element Method ◽  
Reinforcement Effect ◽  
Earthquake Action ◽  
Seismic Deformation

Tailings dam due to earthquake action may lead to severe slippage damage, and setting antiseismic measure is an effective method to prevent damage. Dynamic nonlinear finite element method is used in the efforts to analyze the earthquake reaction and the deformation characteristic. To reduce dam seismic deformation, the reinforcement effect of geotextiles, rock pressure and stone column is studied. Finally, a synthetically antiseismic measure that is composed of geotextiles-reinforced in sub-dam, rock pressure out of starter dam and densification foundation is proposed. It is found that the synthetically antiseismic measure produces better antiseismic effect, and offers a consult for the antiseismic design of tailings dam.

scholarly journals Quantitative Support for Borowski’s Theory of Gravitation

2013 ◽  
Vol 17 ◽  
pp. 67-71 ◽  
Author(s):  
Michael A. Persinger
Keyword(s):  
Dark Matter ◽  
Gravitational Constant ◽  
Planetary Motion ◽  
Free Oscillations ◽  
Energy Equivalence ◽  
Order Of Magnitude ◽  
Theory Of Gravitation

The Borowski Theory of Gravitation (BTG) indicates that movements of mass such as planets through space are determined by differential pressures from dark matter. One of the consequences of the final epoch is that there would be no matter but only distance. Quantitative solutions indicate that the tensor to set universal average dark matter pressure equal to G, the gravitational constant, would require that the terminal length would be ~2.2∙1069 m or effectively identical to current estimates of energy equivalence of the universal mass. For the earth’s orbit the force from the dark pressure is the same order of magnitude as the force associated with the product of the planet’s mass and background free oscillations whose origins are still ambiguous. The convergences of solutions suggest that the BTG may reveal alternative interpretations and mechanisms for the role of gravitation in planetary motion.

Sign in / Sign up

Export Citation Format

Share Document