Contents of Journal of Mechanical Engineering 56, 1 (2005) 


 

AL-ATABI, M. T., ASRAR, W.: Fluiding thrust vectoring: Challenges 
and opportunities                                                           1 

OKROUHLIK, M., PTAK, S.: Assessment of experiment by finite element
analysis: Comparison, self-check and remedy                                18

QIN, Q.-H.: Trefftz plane elements of elastoplasticity with p-extension
capabilities                                                               40   

AMBROZIK, A.: Method of determination of the heat emission coefficient
in combustion process                                                      60

Abstracts



Fluiding thrust vectoring: Challenges and opportunities

MUSHTAK TALIB AL-ATABI, WAQAR ASRAR

Fluiding thrust vectoring is a process of altering the direction of an exhaust jet utilizing fluidic means, i.e. without mechanical intervention. This technique carries a lot of promises for both civilian and military aerospace industries. Among others, it can be employed to improve and realize concepts like blended wing body (BWB) aircraft, tailless aircraft, unmanned combat airborne vehicle (UCAV) and stealth aircraft. A review of the available work concerning the principle of fluidic thrust vectoring is presented in this paper. Pros and cons of the principle are highlighted.

Assessment of experiment by finite element analysis:
Comparison, self-check and remedy

MILOSLAV OKROUHLIK, SVATOPLUK PTAK

Cylindrical metallic thin shell subjected to localized impact loading evoking linear wave response was considered. Experiments were carried out employing the double pulse holographic interferometry (DPHI) for evaluation of displacements, the Doppler interferometry (DI) for velocities and the piezoelectric accelerometers (PA) for the registration of accelerations, while the finite element (FE) method was used for the numerical analysis. The paper compares experimental and numerical responses with intention to discuss the accuracy limits of experimental and numerical approaches and to suggest certain remedy steps for making the experimental process more ´reproducible´ by means of suitable on-line experimental checks.

Trefftz plane elements of elastoplasticity with p-extension capabilities

QING-HUA QIN

The present investigation is concerned with the development of Trefftz element formulation of two-dimensional elastoplastic solid with p-method capabilities. A modified variational functional is introduced and used to derive hybrid Trefftz finite element formulation for elastoplasticity of bulky solids. The formulation is applicable to either strain hardening or elastic perfectly plastic materials. A solution algorithm based on initial stress formulation is implemented into the new element model. The performance of the proposed element model is assessed by two examples and comparison is made with results obtained by other approaches.

Method of determination of the heat emission coefficient
in combustion process

ANDRZEJ AMBROZIK

Basic issues concerning the working cycles of piston, four-stroke, internal combustion engines are discussed in the paper. It presents the methodology worked out to determine the value of the effective heat emission coefficient in combustion with the use of theoretical and real diagrams of the engine working cycles. The proposed methodology was based on Sabathe theoretical working cycle, in which the heat is conveyed to the working medium in the cylinder partially at constant volume q1´ and partially at constant pressure q1´´. The way of coefficient  \xi determination presented in the paper can be used for the determination of the real values of  \xi for various operating conditions of piston self-ignition internal combustion engines. The values of  \xi thus obtained enable us to conduct more accurate theoretical calculations and analyses of real indicator diagrams of IC engines.