Wyniki wyszukiwania - Biblioteka Nauki

1

Nonlinear method of precrash velocity determination for Mini car class-B-spline tensors products with probabilistic weights

100%

Mrowicki A. , Kubiak P. , Zakrzewicz W.

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tom Vol. 87, nr 1

97--108

EN

Following paper introduces the nonlinear method of determining the velocity of a vehicle before the impact-the Equivalent Energy Speed (EES). To estimate the magnitude of EES, the method utilizes the deformation work Wdef of the vehicle, defined by the quotient of deformation coefficient Cs and plastic deformation. Combined with the introduction of the B-spline tensor products and least square approximation with probabilistic weights, method shows promising results.

2

High compression spark ignition engine with variable compression ratio using Active Combustion Chamber

88%

Kubiak P. , Glogowski M. , Soghabatyan T. , Mrowicki A. , D'Errico G.

Archiwum Motoryzacji

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2019

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tom Vol. 86, nr 4

5--26

EN

Abstract In this article Authors present the continuation of the calculations for theoretical ACC engine cycle, considering additionally “VCR function” – changeable compression level. For this purpose the self-acting volume change, realized by ACC system, was used. The ACC system was adjusted appropriately to control the compression level. The analysis is based on three cases, representing delayed, premature and optimal reaction of ACC system. Reactions are presented in form of plots with indicated pressure in the combustion chamber. As the result of the conducted analysis and interpretation of obtained graphs, the calculation approach of compression ratio for ACC presented in previous article is being challenged. For the optimal reaction of ACC system, the theoretical operation schematics are devised and presented in the key points of the work. Based on the schematics, the values of theoretical efficiency were calculated for different cycles of theoretical ACC engine, in which regulation of compression ratio takes place. Moreover, the presented analysis includes graphs with optimal courses of indicated pressure for significantly different work parameters of ACC engine, showing its regulation possibilities. Also the time scaled graphs (with millisecond as basic time unit) are presented to show the possibilities of dynamic ACC systems, which are comparable with the combustion time (from 3 to 0,5 ms). In this paper the general discussion is started about the compression ratio in more complex kinematic systems including ACC.

3

Nonlinear method of precrash vehicle velocity determination based on tensor product of Legendre polynomials - luxury class

75%

Gosławski Ł. , Sys E. , Mrowicki A. , Krukowski M. , Ma Y. , Kubiak P.

Archiwum Motoryzacji

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2022

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tom Vol. 95, nr 1

53--64

EN

Presented paper discusses a new, nonlinear approach to EES (Equivalent Energy Speed) parameter determination in frontal car collisions. This method is based on tensor product of Legendre polynomials and in this case considers Luxury car class. Methods that are used up till now are based on a linear dependency between mass, velocity and deformation. This is of course a simplification that was necessary, due to limitation in computation power of computers when this method was introduced decades ago. The contemporary resources allowed Authors to develop a much more sophisticated method. The mathematical model was developed using data shared by National Highway Traffic Safety Administration (NHTSA). This database covers a large number of test cases along with various information including vehicle mass, crash velocity, chassis deformation etc. New method proves to be more accurate than the currently used approach utilizing linear dependency of deformation force and deformation of the vehicle.

4

Precrash vehicle velocity determination using inverse system and tensor product of Legendre polynomials - subcompact car class

75%

Gosławski Ł. , Madziara S. , Droś B. , Knap L. , Ma Y. , Mrowicki A.

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tom Vol. 97, nr 3

14--24

EN

Presented paper discusses new approach to EES parameter determination in frontal car crash based on the tensor product of Legendre polynomials. In this paper Subcompact Car Class was analyzed using that method. Data that was used to perform analyses introduced in this paper was taken from National Highway Traffic Safety Administration (NHTSA) database. Such database consists of considerate number of test cases along with various information including vehicle mass, crash velocity, chassis deformation etc. New approach to the problem of determining the EES parameter was necessary due to the low accuracy of the currently used methods. Linear models used up till now for accident reconstruction show significant error as the relationship between mass, velocity and deformation cannot be well approximated with a flat plane. Proposed model produces better results, because of the nonlinear dependence of said parameters. This paper also includes a calculation example presenting a comparison of linear and nonlinear method on an actual crash test.

5

Nonlinear method of determining the vehicle pre-crash speed based on B-spline with propabilistic weights - subcompact car class

63%

Kubiak P. , Sys E. , Goslawski L. , Manko M. , Gralewski J. , Krukowski M. , De Sousa R. A. , Mrowicki A. , Soghabatyan T. , Zou T.

Archiwum Motoryzacji

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2019

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tom Vol. 85, nr 3

5--18

EN

A new non-linear method utilizing the work W of car deformation is considered in this study. The car deformation is defined as an algebraic function of deformation ratio Cs. The method of variable correlation is exploited in order to develop experimental data. To determinate mathematical model parameters, data from the NHTSA database including frontal crash tests are used. Such database is comprised of substantial number of crash cases and main focus was put on frontal impacts. In the non-linear method used so far, the so-called energetic approach, collisions are considered non-elastic. The speed threshold defining the elastic collision was set to be 11 km/h. This simplistic approach is used to determine the linear relation of energy loss during deformation on deformation coefficient Cs. Deformation points C1-C6 are taken into account while calculating a mean value that defines this coefficient. A more accurate non-linear method as well as more complex form of deformation coefficient is suggested to determine the work of deformation in this paper. The focus of those methods is to establish the value of nonlinear coefficient b_k which is the slope factor of precrash velocity Vt and deformation ratio Cs function.

6

Research of damage to the rear wheel rim in a tipper-truck

63%

Kubiak P. , Wozniak M. , Zakrzewski S. , Siczek K. , Rylski A. , Mrowicki A. , Matej J. , Deda J. , Knap L.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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tom Vol. 70, nr 3

art. no. e141000

EN

Serious damage to the inner rim of the rear twin wheel in one dump truck was noted during the operation of the fleet performing transport tasks. It was a drive wheel, and its damage occurred while driving with a load exceeding the permissible value. The examination of selected fragments of the damaged rim surface was conducted visually as well as using a digital microscope with a portable head. The measurements of the Vickers hardness and microscopic observations of the material structure of the sample cut along the thickness of the rim disk were carried out. The drive torque loading of the twin wheels of the tipper-truck rear axle, under their mating with different kinds of road roughness and under various vertical loads of the wheels was calculated. An analysis of stress distributions in the rim modelled using the Finite Element Method was also conducted for several possible scenarios of wheel loading. The damage to the rim was caused by simultaneous action of several factors, such as overloading the car, poor condition of the tires, loading the drive wheel by a part of the vehicle weight and the driving torque, and hitting a wheel on a cavity in a dirt road, causing a temporary relief of one of the tires on a twin wheel.