Edge States in Nonlinear Model of Valve Spring

2019 ◽  
Author(s):  
Majdi Gzal ◽  
Oleg V. Gendelman
Keyword(s):  
Combustion Engine ◽  
Edge State ◽  
Edge States ◽  
Valve Spring ◽  
Localized Solutions ◽  
Strong Localization ◽  
Experimental Findings ◽  
Mass Spring ◽  
The Impact ◽  
Time Periodic

Abstract We address the dynamics of helical compression valve springs of an internal combustion engine. To this end, the spring is mathematically modeled as a finite non-homogenous one-dimensional mass-spring-damper discrete chain. Regarding the boundary conditions, the upper end of the chain is forced with periodic displacement, which mimics the actual camshaft profile, while the other end is fixed. In order to model the interaction between the valve and valve seat, the displacement of the upper mass is constrained to be nonnegative by adding an obstacle such that when it approaches the obstacle, it experiences an impact that satisfies the Newton impact law with restitution coefficient less than unity. Another source of damping in this model arising from the internal damping of the spring material. The nonlinearity of the model originates from the periodic impact interactions. This interplay between nonlinearity and discreteness supports time-periodic and spatially localized solutions characterized by a strong localization at the edge of the chain (i.e. edge states) such that the periodicity of the impact allows derivation of exact analytical solutions for the forced-damped edge state. Then, the governing equations are solved numerically in order to illustrate the exact solution. The results are compared to experimental findings from analysis of actual automotive valve spring.

scholarly journals Vibro-Acoustical Sensitivities of Stiffened Aircraft Structures Due to Attached Mass-Spring-Dampers with Uncertain Parameters

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 174
Author(s):  
Johannes Seidel ◽  
Stephan Lippert ◽  
Otto von Estorff
Keyword(s):  
System Response ◽  
Fuzzy Arithmetic ◽  
Parameter Uncertainties ◽  
Excitation Spectra ◽  
Radiated Noise ◽  
Linking Elements ◽  
Manufacturing Tolerances ◽  
Suitable Framework ◽  
Mass Spring ◽  
The Impact

The slightest manufacturing tolerances and variances of material properties can indeed have a significant impact on structural modes. An unintentional shift of eigenfrequencies towards dominant excitation frequencies may lead to increased vibration amplitudes of the structure resulting in radiated noise, e.g., reducing passenger comfort inside an aircraft’s cabin. This paper focuses on so-called non-structural masses of an aircraft, also known as the secondary structure that are attached to the primary structure via clips, brackets, and shock mounts and constitute a significant part of the overall mass of an aircraft’s structure. Using the example of a simplified fuselage panel, the vibro-acoustical consequences of parameter uncertainties in linking elements are studied. Here, the fuzzy arithmetic provides a suitable framework to describe uncertainties, create combination matrices, and evaluate the simulation results regarding target quantities and the impact of each parameter on the overall system response. To assess the vibrations of the fuzzy structure and by taking into account the excitation spectra of engine noise, modal and frequency response analyses are conducted.

scholarly journals The Development of Strategies to Reduce Exhaust Emissions from Passenger Cars in Rzeszow City—Poland. A Preliminary Assessment of the Results Produced by the Increase of E-Fleet

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1046
Author(s):  
Maksymilian Mądziel ◽  
Tiziana Campisi ◽  
Artur Jaworski ◽  
Giovanni Tesoriere
Keyword(s):  
Particulate Matter ◽  
Electric Vehicles ◽  
Combustion Engine ◽  
Present Report ◽  
Exhaust Emissions ◽  
Motor Vehicles ◽  
Strategic Choices ◽  
Passenger Cars ◽  
Particulate Concentration ◽  
The Impact

Urban agglomerations close to road infrastructure are particularly exposed to harmful exhaust emissions from motor vehicles and this problem is exacerbated at road intersections. Roundabouts are one of the most popular intersection designs in recent years, making traffic flow smoother and safer, but especially at peak times they are subject to numerous stop-and-go operations by vehicles, which increase the dispersion of emissions with high particulate matter rates. The study focused on a specific area of the city of Rzeszow in Poland. This country is characterized by the current composition of vehicle fleets connected to combustion engine vehicles. The measurement of the concentration of particulate matter (PM2.5 and PM10) by means of a preliminary survey campaign in the vicinity of the intersection made it possible to assess the impact of vehicle traffic on the dispersion of pollutants in the air. The present report presents some strategies to be implemented in the examined area considering a comparison of current and project scenarios characterized both by a modification of the road geometry (through the introduction of a turbo roundabout) and the composition of the vehicular flow with the forthcoming diffusion of electric vehicles. The study presents an exemplified methodology for comparing scenarios aimed at optimizing strategic choices for the local administration and also shows the benefits of an increased electric fleet. By processing the data with specific tools and comparing the scenarios, it was found that a conversion of 25% of the motor vehicles to electric vehicles in the current fleet has reduced the concentration of PM10 by about 30% along the ring road, has led to a significant reduction in the length of particulate concentration of the motorway, and it has also led to a significant reduction in the length of the particulate concentration for the access roads to the intersection.

Methodology to Evaluate the Fuel Economy of a Multimode Combustion Engine With Three-Way Catalytic Converter

2014 ◽  
Author(s):  
Sandro P. Nüesch ◽  
Anna G. Stefanopoulou ◽  
Li Jiang ◽  
Jeffrey Sterniak
Keyword(s):  
Fuel Economy ◽  
Combustion Engine ◽  
Catalytic Converter ◽  
Oxygen Storage ◽  
Nox Emissions ◽  
Combustion Mode ◽  
Mode Switch ◽  
Drive Cycle ◽  
Finite State ◽  
The Impact

Highly diluted, low temperature homogeneous charge compression ignition (HCCI) combustion leads to ultra-low levels of engine-out NOx emissions. A standard drive cycle, however, would require switches between HCCI and spark-ignited (SI) combustion modes. In this paper a methodology is introduced, investigating the fuel economy of such a multimode combustion concept in combination with a three-way catalytic converter (TWC). The TWC needs to exhibit unoccupied oxygen storage sites in order to show acceptable performance. But the lean exhaust gas during HCCI operation fills the oxygen storage and leads to a drop in NOx conversion efficiency. Eventually the levels of NOx become unacceptable and a mode switch to a fuel rich combustion mode is necessary in order to deplete the oxygen storage. The resulting lean-rich cycling leads to a penalty in fuel economy. In order to evaluate the impact of those penalties on fuel economy, a finite state model for combustion mode switches is combined with a longitudinal vehicle model and a phenomenological TWC model, focused on oxygen storage. The aftertreatment model is calibrated using combustion mode switch experiments from lean HCCI to rich spark-assisted HCCI and back. Fuel and emissions maps acquired in steady state experiments are used. Two depletion strategies are compared in terms of their influence on drive cycle fuel economy and NOx emissions.

Analytical Study of a Piezoelectric Frequency Up-Conversion Harvester Under Sawtooth Wave Excitation

2018 ◽  
Author(s):  
Saeed Onsorynezhad ◽  
Amin Abedini ◽  
Fengxia Wang
Keyword(s):  
Numerical Solutions ◽  
Excitation Frequency ◽  
Dynamics Analysis ◽  
Periodic Motions ◽  
Lumped Model ◽  
Sawtooth Wave ◽  
Piezoelectric Beam ◽  
Period 2 ◽  
Mass Spring ◽  
The Impact

In this work, an impact based frequency up-conversion mechanism is studied via discontinuous dynamics analysis. The mechanism consists of a moving stopper and a piezoelectric beam. The repeated free vibration of the piezoelectric beam achieved through the impaction between the stopper and the beam, With the stopper excited by a sawtooth wave. Due to the impact, the system contains complex discontinuous dynamics, hence to better understand the energy harvesting performance of the piezoelectric beam, we seek the simple periodic motions of the system. As the system parameter varies, the output voltage and power of the piezoelectric beam with periodic motions is obtained. These results were also compared with those obtained when the piezoelectric beam is directly subjected to the same sawtooth wave. The piezoelectric beam was modeled as a mass-spring-damper system, and the linear piezoelectric constitutive equations have been used to obtain the lumped model of the piezoelectric beam. In this study, numerical solutions of the generated power and voltage were obtained via discontinuous dynamics analysis. When the excitation frequency is low, the effect of frequency-up-conversion is demonstrated by comparing the generated power of two cases: piezoelectric beam excited via impact and beam directly subject to the sawtooth wave. The stable and unstable periodic motions and bifurcation trees of the impact parameters are predicted analytically versus varying excitation frequency for period-1 and period-2.

scholarly journals OVERVIEW OF DISTANCE ENERGY TRANSMISSION MEANS FOR POWERING AGRICULTURAL MACHINERY TAKING INTO ACCOUNT FACTORS AFFECTING HUMAN SAFETY

2021 ◽  
Vol 4 (164) ◽  
pp. 10-13
Author(s):  
V. Halil ◽  
S. Zakurdai ◽  
V. Scurikhin ◽  
O. Donets ◽  
D. Zubenko
Keyword(s):  
Combustion Engine ◽  
Renewable Energy Sources ◽  
Electrical Energy ◽  
Electric Transport ◽  
Electric Motors ◽  
Agricultural Machinery ◽  
Transport Equipment ◽  
Agricultural Equipment ◽  
Electric Traction ◽  
The Impact

This article discusses the issues of autonomous operation of electrical agricultural equipment based on the transmission of electricity over a distance. The main point of this article is that tractors that work in the field are driven by electric motors, with the need to use expensive batteries. The issues of the impact and safety of this technology on the environment and humans are considered. The main problem of the creation, maintenance and operation of transport equipment, including agricultural equipment, is the high cost of maintenance and fuel, which are constantly increasing. In addition, the environmental problem, which has become so acute in recent years, global warming, the fuel crisis and the need to transfer all transport equipment to electric traction, make us look for new ways to solve the problem of environmental pollution and save resources, especially non-renewable energy sources. The use of electrical energy for traction of agricultural machinery that work in the fields or in other industries has been used for a long time, and in the early stages of the development of transport, it was electric transport that occupied the main part, before the invention of the internal combustion engine. Including at the Kharkov Tractor Plant there were developments (and still are), a prototype of the use of electric motors as the main unit for movement. Based on the above, it is obvious that electric traction for transport is obviously environmentally friendly and safe, although there are a number of limitations in this matter as well, but the unresolved problems of the limited use of the storage battery force us to look for new sources of energy. This article proposes to consider the possibility of using electric traction for agricultural machinery with the supply of operating tractors in the fields with the help of a directed electromagnetic wave with its transformation into electrical energy, which will be supplied to the electric motor.

Natural convection flow in a vertical micro-annulus with time-periodic thermal boundary conditions

2018 ◽  
Vol 14 (5) ◽  
pp. 1064-1081
Author(s):  
Basant Kumar Jha ◽  
Michael O. Oni
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Skin Friction ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
The Impact ◽  
Time Periodic

PurposeThe purpose of this paper is to investigate the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.Design/methodology/approachAnalytical solution in terms of Bessel’s function and modified Bessel’s function of order 0 and 1 is obtained for velocity, temperature, Nusselt number, skin friction and mass flow rate.FindingsIt is established that the role of Knudsen number and fluid–wall interaction parameter is to decrease fluid temperature, velocity, Nusselt number and skin friction.Research limitations/implicationsNo laboratory practical or experiment was conducted.Practical implicationsCooling device in electronic panels, card and micro-chips is frequently cooled by natural convection.Originality/valueIn view of the amount of works done on natural convection in microchannel, it becomes interesting to investigate the effect that time-periodic heating has on natural convection flow in a vertical micro-annulus. The purpose of this paper is to examine the impact of time-periodic thermal boundary conditions on natural convection flow in a vertical micro-annulus.

Analytical Determination of Shock Response Spectra for an Impulse-Loaded Proportionally Damped System

Volume 1 ◽  
2004 ◽  
Author(s):  
R. David Hampton ◽  
Nathan S. Wiedenman ◽  
Ting H. Li
Keyword(s):  
Transient Response ◽  
Shock Loading ◽  
Response Spectrum ◽  
Response Spectra ◽  
Analytical Determination ◽  
System Response ◽  
Mechanical Shock ◽  
Shock Response ◽  
Mass Spring ◽  
The Impact

Many military systems must be capable of sustained operation in the face of mechanical shocks due to projectile or other impacts. The most widely used method of quantifying a system’s vibratory transient response to shock loading is called the shock response spectrum (SRS). The system response for which the SRS is to be determined can be due, physically, either to a collocated or to a noncollocated shock loading. Taking into account both possibilities, one can define the SRS as follows: the SRS presents graphically the maximum transient response (output) of an imaginary ideal mass-spring-damper system at one point on a flexible structure, to a particular mechanical shock (input) applied to an arbitrary (perhaps noncollocated) point on the structure, as a function of the natural frequency of the imaginary mass-spring-damper system. For a response point sufficiently distant from the impact area, many Army platforms (such as vehicles) can be accurately treated as linear systems with proportional damping. In such cases the output due to an impulsive mechanical-shock input can be decomposed into exponentially decaying sinusoidal components, using normal-mode orthogonalization. Given a shock-induced loading comprising such components, this paper provides analytical expressions for the various common SRS forms. The analytical approach to SRS-determination can serve as a verification of, or an alternative to, the numerical approaches in current use for such systems. No numerical convolution is required, because the convolution integrals have already been accomplished analytically (and exactly), with the results incorporated into the algebraic expressions for the respective SRS forms.

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