scholarly journals Vibroacoustic Assessment of an Innovative Composite Material for the Roof of a Coupe Car

2021 ◽  
Vol 11 (3) ◽  
pp. 1128
Author(s):  
Nunziante Cascone ◽  
Luca Caivano ◽  
Giuseppe D’Errico ◽  
Roberto Citarella
Keyword(s):  
Composite Material ◽  
Transfer Functions ◽  
Realistic Model ◽  
Point Of View ◽  
Damping Capacity ◽  
Geometry Structure ◽  
Fiberglass Composite ◽  
New Material ◽  
Static Rigidity ◽  
Innovative Material

The objective of this paper is the vibroacoustic evaluation of an innovative material for a sports car roof, aiming at replacing fiberglass composite materials. Such evaluation was carried out using numerical and experimental analysis techniques, with cross-comparison between the corresponding results. The innovative material under analysis is a composite material, with a thermoplastic polypropylene matrix and reinforcement made of cellulose fibers. In order to validate the virtual dynamic modeling of the new material, the inertance on different points of some sheets made of the material under analysis was evaluated by an in-house made experimental activity, performed in the CRF (Fiat Research Center) test room, and cross-compared with corresponding results from a numerical analysis performed with the MSC Nastran software. Then, a realistic model of the car roof of the Alfa Romeo 4C car, made with the new material, was implemented and analyzed from the vibroacoustic point of view. The mere switch to the new material, with no changes in the geometry/structure of the car roof, did not allow preserving the original values of static rigidity, dynamic rigidity, and configuration of modal shapes. For this reason, a geometric/structural optimization of the component was performed. Once the new geometry/structure was defined, a vibroacoustic analysis was carried out, checking for a possible coupling between the fluid cavity modes and the structure car body modes. Finally, the vibroacoustic transfer functions to the driver’s ear node were assessed, considering two different excitation points on the structure. The excellent damping capacity of the proposed material led to an improvement in the vibroacoustic transfer functions and to a reduction in the weight of the pavilion.

scholarly journals INITIAL RESEARCH OF MINERAL BASED ANTI-CORROSION MULTICOMPONENT COMPOSITE MATERIAL

2019 ◽  
Vol 48 (05) ◽  
pp. 142-147
Author(s):  
Emil Asgarov
Keyword(s):  
Composite Material ◽  
Extreme Values ◽  
Extreme Value ◽  
Point Of View ◽  
Protective Film ◽  
Weak Point ◽  
Variable Function ◽  
New Material ◽  
Film Layer ◽  
Multicomponent Composite

The new approach is to create a multicomponent composite material on a basis of mineral component by defining extreme value of the multi-variable function. It is decided to carry out theoretical analyze first. For theoretical analysis, the effects of component quantity on the parameters to be determined by experiments and in all cases the results to be theorized. Thus, the mathematical formula for the relation of anti-corrosion with components has been determined. In order to evaluate anti-corrosion it is defined multi-variablefunctional relation and with this function it is achieved extreme values on optimum values of each component. The new material is compared to traditional anti –corrosion material that are common. Currently implemented anti –corrosion material doesn’t require needs of modern technological expectation. From this point of view anti-corrosion materials need to have appropriate technical parameters. Traditional anti-corrosion materials basically have one or two components and these materials has protective film layer. Disadvantage of this film layer is whole layer can easily be destructed from weak point. This is due to the fact that traditional materials form film layer in connection areas. Compare with this one the new material has discrete structure. On this basis, the combination of protective and constructive material binding based on adhesion and cohesion. The structure not allows material to be destructed from weak point. On a basis of achieved theoretical results optimal quantity of each component is clarified, anti-corrosion material is made and tested. The novelty of the approach is to achieve high quality anti-corrosion material by defining an extreme value of the multi-variable function.

ERRORS CONVERSION ON TRANSFER FUNCTIONS OF MEASUREMENT AND CONTROL

2021 ◽  
Vol 4 ◽  
pp. 92-104
Author(s):  
Valentin Bahatskyi ◽  
◽  
Aleksey Bahatskyi ◽  
Keyword(s):  
Transfer Functions ◽  
Systematic Errors ◽  
Step Function ◽  
Control Device ◽  
Point Of View ◽  
Correct Operation ◽  
Analog To Digital ◽  
Analog To Digital Conversion ◽  
And Control ◽  
Measurement And Control

Currently, the measurement of electrical and non-electrical quantities is performed using analog-to-digital conversion channels, which consist of analog signal conditioning circuits and analog-to-digital converters (ADC) of electrical quantities into a digital code. The paper considers the case when the defining errors of the measurement and control channel are systematic errors of the ADC. The reliability of measurements is assessed by their errors, and the reliability of control - by the likelihood of correct operation of the control device. In our opinion, evaluating the reliability of such similar processes as measurement and control using different criteria seems illogical. The aim of the work is to study the effect of systematic errors of an analog-to-digital converter on the errors of parameter control depending on the type of conformity functions and the width of the control window, as well as the choice of the resolution of the ADC for various control tasks. The paper analyzes the transfer functions of measurement and control. It is shown that they are formed using step functions. It is proposed to use not a step function as a control transfer function, but other functions of conformity to the norm, for example, a linear function or functions of higher orders. In this case, the control result is assessed not according to the criterion of the probability of correct operation, but using the control error. Analyzed from the point of view of reconfiguring the errors of the line, parabolic and state parabolic functions of the norms for the development of changes windows in control. A recommendation has been given for the selection of functions for the conformity of standards and for the distribution of analog-to-digital conversions for industrial control enterprises.

Master curves for the response of layered systems to compressional seismic waves

1967 ◽  
Vol 57 (3) ◽  
pp. 515-543 ◽  
Author(s):  
Luis M. Fernandez
Keyword(s):  
Seismic Waves ◽  
Transfer Functions ◽  
Point Of View ◽  
Time Lags ◽  
Master Curves ◽  
Layer System ◽  
Crust And Upper Mantle ◽  
Response Characteristics ◽  
Families Of Curves ◽  
Short Time

abstract The layers of the earth's crust act as a filter with respect to seimic energy arriving at a given station. Consequently the motion recorded at the surface depends not only on the frequency content of the source and on the response characteristics of the recording instrument, but also on the elastic parameters and thicknesses of the transmitting layers. This latter dependence is the basis for a method of investigating the structure of the crust and upper mantle. To facilitate this investigation a set of master curves for the transfer functions of the vertical and horizontal component of longitudinal waves and their ratios is presented. The calculation of these curves is in terms of a dimensionless parameter. This calculation allows one to group the curves corresponding to different crustal models into families of curves. The characteristics of these curves are discussed from the point of view of their “periodicity” in the frequency domain and of their amplitude in order to investigate the influence of the layer parameters. Considerations, either of constructive interference or of Fourier analysis of a pulse multiply reflected within the layer system, reveal that the amplitudes of the transfer curves depend on the velocity contrasts at the interfaces of the system. The “periodicity” or spacing of the peaks depends on the time lags between the first arrivals and the arrivals of the different reverberations. Closely spaced fluctuations correspond to large-time lags, and widely spaced fluctuations to short-time lags.

A Probabilistic Study of the Simultaneous Effect of Ship Motions on the Cargo Shifting Onboard

1996 ◽  
Vol 33 (01) ◽  
pp. 25-34
Author(s):  
Jianbo Hua
Keyword(s):  
Transfer Functions ◽  
Simulation Method ◽  
Point Of View ◽  
Roll Angle ◽  
Ship Motions ◽  
Vertical Acceleration ◽  
Simultaneous Effect ◽  
Strip Theory ◽  
Probabilistic Study ◽  
Mean Wave Period

Cargo movement aboard ship can occur even in waves that produce only moderate rolling motion. It is caused when the simultaneous effect of vertical acceleration, horizontal acceleration and roll motion on the cargo onboard—defined as the equivalent roll angle—becomes sufficiently large for the problem to develop. In this paper, an analytical expression is derived for the probabilistic calculation of the equivalent roll angle, which has a nonlinear characteristic. Also, a so-called indirect time-domain simulation method is described for calculating the problem. Both methods are based on motion transfer functions calculated according to strip theory. The calculations presented here show both methods to be in good agreement. A probabilistic calculation of the equivalent roll angle of a roll-on/roll-off (RO/RO) ship is carried out using the two methods and focusing on parameters such as significant wave height, mean wave period, ship speed, and relative course angle. It is proved from the point of view of probability that the nonlinearity of equivalent roll angle results in a magnifying effect on its extreme value. The calculation shows also that in severe wave conditions large peak values of equivalent roll greater than 35 deg can be experienced by the studied RO/RO ship.

Examination of Microstructure of Cement Composite Material for Renovation of Horizontal Structures

2019 ◽  
Vol 808 ◽  
pp. 103-108
Author(s):  
Lenka Mészárosová ◽  
Vít Černý ◽  
Rostislav Drochytka ◽  
Winfried Malorny
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
High Temperature ◽  
Surface Temperature ◽  
Cement Composite ◽  
Volume Weight ◽  
Coefficient Of Thermal Conductivity ◽  
New Material ◽  
Properties Of Materials ◽  
Low Volume

Development of new material is focused on modification of properties of materials with silicate binder so that these could be used for renovation of horizontal structures of high-temperature devices and at the same time contribute to reduction of heat transportation of constructions with higher surface temperature (in this case 200 and 500 °C). Main requirements for this material is low volume weight and low coefficient of thermal conductivity. This paper assesses influence of exposition to higher temperatures on microstructure.

scholarly journals General Theory of Subglacial Cavitation and Sliding of Temperate Glaciers

1968 ◽  
Vol 7 (49) ◽  
pp. 21-58 ◽  
Author(s):  
L. Lliboutry
Keyword(s):  
Frictional Force ◽  
Atmospheric Pressure ◽  
Hydraulic System ◽  
Water Pressure ◽  
Realistic Model ◽  
Point Of View ◽  
Small Scale ◽  
Sliding Velocity ◽  
Surface Slope ◽  
Geometrical Progression

AbstractEarlier theories of Weertman and the present author are reviewed and compared; both are insufficient to account for the facts observed at the tongue of the Allalingletscher.A calculation of the stresses and heat flow at the bed of a glacier with a sinusoidal profile is given which takes account of any degree of subglacial cavitation. The sliding due to plasticity and that due to pressure melting are related to this degree of cavitation and it is shown that these two terms are additive. There results an expression for the frictionfωin terms of the total sliding velocityuand the height of the bumpsa. For a given and large enough value ofu,fω(a) exhibits two maxima which are equal and independent ofu.The paper then considers a more realistic model of the bed consisting of a superposition of sine waves all having the same roughnessr, andadecreasing in a geometrical progression. The biggestamay be inferred from the overall profile of the bedrock; the resulting frictional force can be regarded either as part of the total frictional forcefin an overall view for whichf=ρghsinαholds, or else as a correction to such a value on the small scale (the best point of view for crevasse studies). To a first approximation Coulomb’s law of friction holds provided one takes account of the interstitial water pressure at the ice-rock interface.This interstitial pressurepis next related to the thickness of the glacierh. If the subglacial hydraulic system is at atmospheric pressure,pis proportional toh. Next, if the sliding velocity is not too large, the surface slope approaches 1.6r≈ 0.12 and kinematic waves (which move four times as fast as the ice) disappear rapidly. If the hydraulic system is not at atmospheric pressure the surface slope is smaller and flow instabilities can occur.

A New Fiber Reinforced Composite Material Properties and Engineering Application

2011 ◽  
Vol 399-401 ◽  
pp. 1294-1297
Author(s):  
Li Xin Yin ◽  
Jing Yan ◽  
Guo Wen Li ◽  
Wei Qiang Xu
Keyword(s):  
Composite Material ◽  
Thermal Insulation ◽  
Low Cost ◽  
Engineering Application ◽  
Outer Wall ◽  
Reinforced Composite ◽  
High Durability ◽  
New Material ◽  
Construction Efficiency ◽  
Reinforced Composite Material

External thermal insulation technology for building external wall has gradually been one important technology of the construction energy conservation. A new fibre reinforced composite material is made up of cement, flyash, silicon ash, the inflation polystyrene pellet and the admixture, after the experiment examination and the engineering application, the effect of thermal insulation is good, the performance of fire proof is excellent, high durability and low cost, good property of sound absorption. Solved the quality problem exist in the traditional building outer wall thermal insulation system such as the thermal insulation layer fall off, split, seep and so on. The new material can product standardize in factory, increase the construction efficiency; in favor of the construction industrialization and could promote construction business sustainable development.

Identification of Material Damping of a Carbon Composite Bar and Study of Its Effect on Attenuation of Its Transient Lateral Vibrations

2015 ◽  
Vol 07 (06) ◽  
pp. 1550081 ◽  
Author(s):  
Jaroslav Zapoměl ◽  
Vladimír Dekýš ◽  
Petr Ferfecki ◽  
Alžbeta Sapietová ◽  
Milan Sága ◽  
...  
Keyword(s):  
Composite Material ◽  
Carbon Composite ◽  
Damping Capacity ◽  
Internal Damping ◽  
Material Damping ◽  
Damping Coefficients ◽  
Lateral Vibrations ◽  
Carbon Composite Material ◽  
Frequency Independent ◽  
Specific Damping Capacity

Reduction of noise and vibrations is one of the major requirements put on operation of modern machines. It can be achieved by application of new materials. The ability to utilize them properly requires learning more about their mechanical properties. Vibration attenuation depends on material damping as an important factor. This paper presents the results of research in a carbon composite material focusing on its internal damping, on the measurement of the damping coefficients and on its implementation into mathematical models. The obtained results were used for investigation of suppressing lateral vibrations of a long homogeneous carbon composite bar oscillating in the resonance area. During the transient period and due to nonlinear effects, the harmonic time-varying loading excites the bar response consisting of a number of harmonic components. The specific damping capacity referred to several oscillation frequencies determined by measurement. The results were evaluated from the point of view of two simple damping theories — viscous and hysteretic. The experiments showed that internal damping of the investigated material could be considered as frequency independent. Therefore, in order to carry out simulations, the bar was represented in the computational model by an Euler beam constituted of Maxwell–Weichert theoretical material. A suitable setting of material constants enabled reaching a constant value of the damping parameters in the required frequency range. The investigated bar vibration is governed by the motion equation in which the internal damping forces depend not only on instantaneous magnitudes of the system’s kinematic parameters but also on their past history. Solution of the equations of motion was performed after its transformation into the state space in the time domain. Results of the computational simulations showed that material damping significantly reduced amplitude of the bar vibrations in the resonance area. The producers of composite materials usually provide material parameters allowing to solve various stationary problems (density, modulus of elasticity, yielding point, strength, etc.), but there is only little or almost no information concerning the data needed for carrying out dynamical or other time-dependent analyses such as internal damping coefficients, fatigue limit, etc. Therefore, determination of the hysteretic character of material damping of the investigated carbon composite material, measurement of its specific damping capacity and implementation of the frequency-independent damping into the computational model are the principal contributions of this article.

scholarly journals Development of Knitted Fabric Reinforced Composite Material for Prosthetic Application

1999 ◽  
Vol 8 (6) ◽  
pp. 096369359900800 ◽  
Author(s):  
Zheng Ming Huang ◽  
S. Ramakrishna
Keyword(s):  
Composite Material ◽  
Knitted Fabric ◽  
Uv Curable ◽  
Prosthetic Socket ◽  
Mechanical Characterisation ◽  
Biomedical Device ◽  
Fabric Composite ◽  
New Material ◽  
Material Fabrication ◽  
Uv Curable Resin

This Letter reports the development of a knitted fabric composite material using Kevlar 49 fibres and ultraviolet (UV) curable resin for a biomedical device, prosthetic socket application. Material fabrication and mechanical characterisation are described. The mechanical properties of this new material are comparable with those of a currently used indirect socket material. Compared with other available direct sockets, this new material is capable of better conforming to patient's stump and has longer gel time for manual operations involved.

Application of Transfer Functions to the Thermal Processing of Sweet and Sour Cherries Preserves: Influence of Particle and Container Sizes

2003 ◽  
Vol 9 (2) ◽  
pp. 69-76 ◽  
Author(s):  
C. A. Márquez ◽  
V. O. Salvadori ◽  
R. H. Mascheroni ◽  
A. De Michelis
Keyword(s):  
Thermal Processing ◽  
Transfer Functions ◽  
Sucrose Solution ◽  
Simulation Method ◽  
Point Of View ◽  
Average Error ◽  
Transfer Function Method ◽  
Glass Containers ◽  
Enzyme Degradation

The conditions of thermal processing of fruit preserves packed in transparent glass containers have great importance from the point of view of the final product appearance. Process simulation can allow to predict the quality of the product and its possible degradation. This work applied the transfer function method to simulate the pasteurisation of whole sweet and sour cherries canned in glass containers, with a 25 °Brix sucrose solution as covering liquid, and the predicted results were experimentally tested. The influence of fruit and container diameters on the treatment times was analysed. Kinetic models for enzyme degradation were coupled to the prediction model as examples of the possibilities of optimising the whole pasteurisation process. The accuracy (average error in predicted temperatures: 2.1%) of the simulation method was satisfactory for practical purposes, its use resulted simple and fast, and it allowed adjusting of pasteurisation times, even during the process.

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