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
AMBROZIK, A.: Method of determination of the heat emission coefficient
in combustion process 60
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
Trefftz plane elements of elastoplasticity with p-extension capabilities
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
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.