Non-linear Torsional Vibration Characteristics of an Internal Combustion Engine Crankshaft Assembly

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.

STUDY ON VIBRATION REDUCTION BEHAVIOR FOR THE HYDRAULIC ENGINE MOUNT

In this paper,the metal hydraulic engine mount (HEM) with the orifice is presented,the construction of HEM is consist of hydraulic cylinder and the spring on the bottom,its mechanical model is given and dynamics equations are set up with considering kinematics conditions and continuous of fluid,the dynamics behavior of HEM including dynamic stiffness of fluid and transferability of HEM are studied here.The example of hydraulic engine mount is calculated,it is shown that the vibration reduction performance of the hydraulic engine mount of this paper is better.The analysis method of vibration reduction behavior for HEM in this paper can be used in designing of the reduction vibration devices and the HEM in this paper can be used in the practical engineering for reduction vibration.

Identification of Axial Vibration Excitation Source in Vehicle Engine Crankshafts Using an Auto-regressive and Moving Average Model

Violent axial vibration of a vehicle engine crankshaft might lead to multiple defects to the engine.Much research on mechanism and control measures has been done on engines,such as using the dynamic stiffness matrix method,rayleigh differential method,and system matrix method.But the source of axial vibration has not been identified clearly because there are many excitation factors for the axial vibration of a crankshaft,such as coupled torsional-axial vibration and coupled bending-axial vibration,etc.In order to improve the calculation reliability and identify the excitation source of axial vibration of in vehicle engine crankshafts,this paper presents a method to identify the axial vibration excitation source of crankshafts for high speed diesel engines based on an auto-regressive and moving average（ARMA） model.Through determining initial moving average variables and measuring axial /bending/torsional vibrations of a crankshaft at the free-end of a 4-cylinder diesel engine,autoregressive spectrum analysis is applied to the measured vibration signal.The results show that the axial vibration of the crankshaft is mainly excited by coupled bending vibration at high speed.But at low speed,the axial vibration in some frequencies is excited primarily by torsional excitation.Through investigation of axial vibration source of engine crankshafts,calculation accuracy of vibration can be improved significantly.

Asymmetric vibration characteristics of two-cylinder four-stroke single-piston hydraulic free piston engine

The structure and working principle of a two-cylinder four-stroke single-piston hydraulic free piston engine(HFPE) were introduced. The basic vibration equation of free piston assembly(FPA) was established based upon the energy conversion between the injected fuel and the friction together with the load. Both the theoretical and numerical results show that the vibration system of FPA is a nonlinear conservative autonomous system in one cycle. The FPA vibration is symmetric with constant amplitude when FPA is only driven by the compression pressure in the compression accumulator and that in the combustion chamber. When considering the friction and load, FPA could still achieve a stable vibration after a few cycles' adjustment whether the input energy is equal to the consumed energy or not. The vibration characteristics are different when FPA vibrates in the compression stroke and the expansion stroke, which is the unique feature of the single-piston HFPE.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Copyright Submission of a manuscript implies:that the work described has not been published before(except in the form of an abstract or as part of a published lecture,review,or thesis);that it is not under consideration for publication elsewhere;that its publication has been approved by all co-authors,if any,as well as-tacitly or explicitly-by the responsible authorities at the institution where the work was carried out.The author warrants that his/her

Earthquake Engineering and Engineering Vibration

Journal web site:http://www.springerlink.comAIMS AND SCOPE This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Copyright Submission of a manuscript implies： that the work described has not been published before （except in the fon＇n of an abstract or as part of a published lecture, review, or thesis）; that it is not under consideration for publication ersewhere： that its publication has been approved by all co-authors, if any, as well as - tacitly or explicitly - by the responsible authorities at the institution where the work was carried out.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Copyright Submission of a manuscript implies: that the work described has not been published before (except in the form of an abstract or as part of a published lecture, review, or thesis); that it is not under

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Submission of a manuscript implies： that the work described has not been published before （except in the form of an abstract or as part of a published lecture, review, or thesis）; that it is not under consideration for publication elsewhere; that its publication has been approved by all co-authors, if any, as well as - tacitly or explicitly - by the responsible authorities at the institution where the work was carried out.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Copyright Submission of a manuscript implies: that the work described has not been published before (except in the form of an abstract

Earthquake Engineering and Engineering Vibration

Journal web site:http://www.springerlink.comAIMS AND SCOPE This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.

Earthquake Engineering and Engineering Vibration

Copyright Submission of a manuscript implies:that the work described has not been published before(except in the form of an abstract or as part of a published lecture,review,or thesis);that it is not under consideration for publication elsewhere;that its publication has been approved by all co-authors,if any,as well as-tacitly or explicitly-by the responsible authorities at the institution where the work was carried out.The author warrants that his/her

Detection of cylinder pressure in diesel engines using cylinder head vibration and time series methods

This paper investigates the vibration characteristics of diesel engine cylinder heads by means of the time series method. With the concept of "Assumed System",the vibration transfer function of real cylinder head structures is established using the autoregressive-moving average models(ARMA models) of cylinder head surface vibration signals. Then this transfer function is successfully used to reconstruct the gas pressure trace inside the cylinder from measured cylinder head vibration signals. This offers an effective means for diesel engine cylinder pressure detection and condition monitoring.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION

Copyright Submission of a manuscript implies： that the work described has not been published before （except in the form of an abstract or as part of a published lecture, review, or thesis）; that it is not under consideration for publication elsewhere; that its publication has been approved by all co-authors, if any, as well as - tacitly or explicitly - by the responsible authorities at the institution where the work was carried out. The author warrants that his/her contribution is original and that he/she has full power to make this grant. The author signs for and accepts responsibility for releasing this material on behalf of any and all co-authors. Transfer of copyright to Institute of Engineering Mechanics, China Earthquake Administration and Springer becomes effective if and when the article is accepted for publication. After submission of the Copyright Transfer Statement signed by the corresponding author, changes of authorship or in the order of the authors listed will not be accepted by Institute of Engineering Mechanics, China Earthquake Administration and Springer. The copyright covers the exclusive right （for U.S. government employees： to the extent transferable） to reproduce and distribute the article, including reprints, translations, photographic reproductions, microform, electronic form （offline, online） or other reproductions of similar nature.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION. AIMS AND SCOPE

This journal, published biannually, is established by the Institute of Engineering Mechanics (IEM), China Earthquake Administration, in cooperation with the Multidisciplinary Center for Earthquake Engineering Research (MCEER), University at Buffalo, State University of New York, to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation, preparedness, and recovery.

EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION AIMS AND SCOPE

This journal, published biannually, is established by the Institute of Engineering Mechanics (IEM), China Earthquake Administration, in cooperation with the Multidisciplinary Center for Earthquake Engineering Research (MCEER), University at Buffalo, State University of New York, to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation, preparedness, and recovery.

Earthquake Engineering and Engineering Vibration AIMS AND SCOPE

This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to