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1

The impact of fatigue on static balance in people with chronic ankle instability

Kowalczyk Małgorzata, Truszczyńska-Baszak Aleksandra

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 1

151--160

EN

: The aim of the study was to assess static postural stability under fatigue in subjects with chronic ankle instability – “copers” in comparison with healthy controls. Methods: We conducted a prospective study on a group of 60 young, physically active subjects, divided into 3 groups: I – 14 subjects with unilateral ankle instability, II – 15 subjects with bilateral ankle instability, III – 31 healthy subjects, without ankle instability. The fatigue trial was based on modified Short-Term Fatigue Protocol. Static stabilography was performed with the use of HUR platform. Results: showed an increase in the value of COP trace length after fatigue test in study population I. The level of COP trace length Z before fatigue was significantly lower than after fatigue. Subjects from study population I had higher levels of COP trace length Z in comparison with the control group. The main effect for the group also proved to be significant. Study population I had higher levels of COP trace length Z in comparison with the control group. For the measurement after fatigue, there was significant difference only between the study population I and the control group. Conclusions: The incidence of structural ankle instability was not correlated with functional instability. Subjects with ankle instability, or “copers”, had good functional levels, enabling them to perform sports activities. “Copers” had weakened proprioception in static stabilography tests. Short and intense fatigue protocol weakened the ability to maintain balance in static stabilography test with eyes closed.

2

Comparative Study on Fatigue Life of CFRP Composites with Damages

Baran Marta, Synaszko Piotr, Lisiecki Janusz, Kłysz Sylwester

Fatigue of Aircraft Structures

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2019

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Iss. 11

28--38

EN

In this work, the compressive residual strength tests results, Compression After Impact (CAI), are presented. The specimens were made of carbon-epoxy prepreg E722-02 UHS 130-14. Two variants of specimens were tested: samples undamaged and samples with damage that was centrally introduced by a drop-weight impact, as per the ASTM D7136/7136M standard. An impactor with potential energy equal to 15J and the type of support required by the standard were used. The size of impacted damages, defined as an area of damage on a plane perpendicular to the impact direction, and the equivalent diameter were specified using the flash thermography method. The tests were performed using the fixtures manufactured according to the ASTM D7137/7137M standard. The specimens were compressed to determine the residual strength. This value was afterwards used to specify the force levels for the fatigue tests. The fatigue tests were carried out under force control – with a sinusoidal shape, stress ratio R equal to 0.1 and frequency f 1Hz. Maximum force in a loading cycle Pmax was being increased after each thousand of cycles N until its value was close to the residual strength determined in the previously mentioned tests. In this work, the following relationships were presented: force-displacement P-δ for both static and fatigue tests and displacement-loading cycles δ-N for fatigue tests. A method of conducting the fatigue tests of CFRP composite was proposed, in which both the CAI specimens and CAI fixture were used. This allowed researchers to accelerate making initial comparisons between the two groups of specimens with damages – grouped relative to the way of conditioning.

3

Numerical investigation on low calorific syngas combustion in the opposed-piston engine

Pyszczek R., Mazuro P., Jach A., Teodorczyk A.

Combustion Engines

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2017

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R. 56, nr 2

53--63

EN

The aim of this study was to investigate a possibility of using gaseous fuels of a low calorific value as a fuel for internal combustion engines. Such fuels can come from organic matter decomposition (biogas), oil production (flare gas) or gasification of materials containing carbon (syngas). The utilization of syngas in the barrel type Opposed-Piston (OP) engine arrangement is of particular interest for the authors. A robust design, high mechanical efficiency and relatively easy incorporation of Variable Compression Ratio (VCR) makes the OP engine an ideal candidate for running on a low calorific fuel of various composition. Furthermore, the possibility of online compression ratio adjustment allows for engine the operation in Controlled Auto-Ignition (CAI) mode for high efficiency and low emission. In order to investigate engine operation on low calorific gaseous fuel authors performed 3D CFD numerical simulations of scavenging and combustion processes in the 2-stroke barrel type Opposed-Piston engine with use of the AVL Fire solver. Firstly, engine operation on natural gas with ignition from diesel pilot was analysed as a reference. Then, combustion of syngas in two different modes was investigated – with ignition from diesel pilot and with Controlled Auto-Ignition. Final engine operating points were specified and corresponding emissions were calculated and compared. Results suggest that engine operation on syngas might be limited due to misfire of diesel pilot or excessive heat releas which might lead to knock. A solution proposed by authors for syngas is CAI combustion which can be controlled with application of VCR and with adjustment of air excess ratio. Based on preformed simulations it was shown that low calorific syngas can be used as a fuel for power generation in the Opposed-Piston engine which is currently under development at Warsaw University of Technology.

4

Compression Auto-Ignition Control in a 2-stroke Barrel-type Opposed-Piston Engine

Pyszczek R., Mazuro P., Teodorczyk A.

Archivum Combustionis

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2017

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Vol. 37 nr 1

25--42

EN

The aim of this study is to investigate a possibility of Compression Auto-Ignition (CAI) control in a turbocharged 2-stroke barrel type Opposed-Piston (OP) engine fueled with a gasoline. The barrel type OP engine arrangement is of particular interest for the authors because of its robust design, high mechanical efficiency and relatively easy incorporation of a Variable Compression Ratio (VCR). A 3D CFD numerical simulations of the scavenging and combustion processes were performed with use of the AVL Fire solver that is based on a Finite Volume Method (FVM) discretization and offers a number of tools dedicated to numerical simulations of working processes in internal combustion engines. The VCR and water injection were considered for the ignition timing control. A number of cases was calculated with different engine compression ratios, different equivalence ratios and different amount of injected water. Results show that proposed measures should be appropriate for controlling the CAI combustion process. Furthermore, application of these solutions in the real engine can significantly contribute to increase in efficiency and decrease in emissions.

5

Role of CAI - CAPC - RENEGADE : concept in the field of air transport security

Piwowarczyk R., Paszukow B.

Przegląd Nauk o Obronności

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2016

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R. 1, Nr 1/2

247--253

EN

All countries over the world faced a completely new form of terrorism - air terrorism threat using civilian aircrafts as weapons. The term RENEGADE is used to define civilian aircrafts that are suspected of being used as weapons to perform terrorist attacks. The answer to this threat is the Common Concept in the Field of Air Transport Security.

PL

Wszystkie kraje na całym świecie stanęły w obliczu zupełnie nowej formy terroryzmu - zagrożenia terroryzmem za pomocą samolotów cywilnych jako broni. Termin RENEGADE jest używany do definiowania samolotów cywilnych, które są podejrzane o użycie jako broń do przeprowadzenia ataków terrorystycznych. Odpowiedzią na to zagrożenie jest Wspólna Koncepcja w Dziedzinie Bezpieczeństwa Transportu Lotniczego.

6

Numerical Model of CAI Test for Fibre-Reinforced Polymer Plate

Baszczyński P., Dziomdziora S., Naze R., Kubiak T.

Mechanics and Mechanical Engineering

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2016

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Vol. 20, nr 3

277--293

EN

This article presents numerical simulations of laminates subjected to Compression After Impact (CAI) testing including delamination modelling. Different model of impact damages of laminate were considered. Progressive damage analysis have been employed and different failure criteria have been applied. For each simulation failure load has been estimated as same as the position of damages at destroyed layer. Finally, obtained numerical results were compared with experimental data from referential paper.

7

Software for composites industry

Pest A.

Advanced Technologies in Mechanics

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2015

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Vol. 2, no. 1 (2)

28--31

EN

Composite materials play a significant role not only in the automotive, aerospace, aviation and nautical industry, but their presence is also important in the production of furniture and sports equipment as well as in the energy industry. In this article described are solutions for computer aided design, computer aided manufacturing and computer aided inspection on example of Delcam’s software for the industries that use composite materials.

8

On the high IMEP potential of barrel engines

Mazuro P., Jasiński D., Teodorczyk A.

Silniki Spalinowe

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2011

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R. 50, nr 3

EN

In this work the possibility of very high performance of barrel engine fueled with gasoline is presented. In this engine several new technologies were used in order to achieve the compression assisted ignition (CAI). The control of CAI combustion reagime was obtained by intensive charge stratification and exhaust gas recirculation (EGR). The additional advantage of barrel engine is its axual symmetry which ensures identical conditions in all cylinders. The application of spherical bearings in barrel engine, instead of classical cylindrical ones, allowed for the increase of permissible loads of crank mechanism. Moreover the noise of engine operation at full load has been reduced due to the untypical kinematics of barrel engine crank mechanism and spherical bearings. All these advantageous features resulted in IMEP level of 2.4 MPa for engine fuelling with homogeneous mixture. The maximum rate of pressure rise was at the same time limited to 0.8 MPa/CAD

PL

W pracy przedstawiono możliwość uzyskania bardzo wysokich osiągów w silniku beczkowym zasilanym benzyną. W silniku tym zastosowano szereg rozwiązań, które pozwoliły na uzyskanie kontrolowanego samozapłonu (ang. Controlled Auto-Ignition - CAI). Opanowanie spalania typu CAI osiągnięto dzięki zastosowaniu silnej stratyfikacji oraz kontroli recyrkulacji spalin (ang. Exhaust Gas Recirculation - EGR). Dodatkową zaletą silnika beczkowego jest osiowa symetria silnika zapewniająca identyczne warunki we wszystkich cylindrach. Zastosowanie łożysk sferycznych, zamiast klasycznych walcowych, w silniku beczkowym pozwoliło na zwiększenie dopuszczalnych obciążeń układu korbowego. Dzięki nietypowej kinematyce silnika beczkowego oraz łożyskom sferycznym uzyskano zmniejszenie hałaśliwości pracy silnika przy pełnych obciążeniach. Zalety silnika beczkowego pozwoliły na uzyskanie średniego ciśnienia indykowanego na poziomie 24 bar, przy zasilaniu silnika mieszanką jednorodną, przy jednoczesnym ograniczeniu maksymalnych przyrostów ciśnienia do 8 bar/CAD.

9

Validation of the Numerical Simulation of Iso-octane Auto-ignition Delay Time in Rapid Compression Machine with the Use of ECFM-3Z (Extended Coherent Flame Model - 3 Zones) Combustion Model Against Experimental Data

Jaworski P., Priesching P., Teodorczyk A., Bandel W.

Archivum Combustionis

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2010

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Vol. 30 nr 1-2

1-14

EN

Nowadays combustion models come up to the requirements of engineers. Numerical simulations show good agreement with experimental results of the compression ignition (CI) and spark ignition (SI) engines. Controlled auto-ignition (CAI) has emerged as one of the most promising engine technologies with the potential to combine fuel efficiency and improved emissions performance. Despite considerable advantages controlling the combustion is still an area of on-going research. The combustion models used for engine simulations are not well prepared and they have to be validated with experimental data. In this paper the first step of setting up of the combustion model is presented with the use of experimental results from three different rapid compression machine (RCM) experiments. That kind of work has to be performed before real engine calculations, to give the brief view on the differences in the experimental and simulation data. Also during this work an improved thermodynamic database for the ECFM-3Z combustion model in the FIRE software was introduced.

10

HCCI combustion - a challenge for internal combustion engine

Kowalewicz A.

Silniki Spalinowe

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2009

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R. 48, nr 1

3-9

EN

HCCI engine offers a high thermal efficiency combined with low nitrogen oxides and particulate matter emissions. However the key problem: controlled autoignition (CAI) on which is focused this paper is still not solved. Attempts to solve CAI problem as: variable compression ratio (VCR), variable valve train (VVT), exhaust gas recirculation (EGR) and application of fuels having different volatility characteristics and sensitivity to autoignition are disused. Also possibility of fuelling HCCI engine with natural gas (and ignition improver) is presented.

PL

Silnik o zapłonie samoczynnym zasilany homogeniczną mieszanką (HCCI) oferuje wysoką sprawność przy małej emisji tlenków azotu i cząstek stałych. Jednakże główny problem, jakim jest kontrolowany samozapłon, nie jest jeszcze rozwiązany. Na tym problemie skupia się niniejszy artykuł. Omówiono metody rozwiązania problemu kontrolowanego samozapłonu, takie jak: zmienny stopień sprężania, recyrkulacja gazów wylotowych, zmienne fazy rozrządu oraz zastosowanie jednocześnie dwu paliw o różnej lotności i skłonności do samozapłonu. Przedstawiono także możliwość zasilania silnika HCCI gazem naturalnym (CNG) przy jednoczesnym udziale składników ułatwiających samozapłon.

11

Facilitation of HCCI combustion of biogas at moderate compression ratios by application of fuel reforming and inlet air heating

Wyszynski M. L., Megaritis A., Karlovsky J., Yap D., Peucheret S., Lehrle R. S., Xu H., Golunski S.

Journal of KONES

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2004

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Vol. 11, No. 3-4

347-356

EN

The HCCI shows large benefits in NOx emissions and fuel economy, but is difficult to achieve and control in engines with moderate compression ratios when natural gas and particularly biogas are used as fuel. It has been shown in literature that the addition of hydrogen translates into the lowering of the auto-ignition temperature during the combustion stroke. A major efforts is being devoted to developing further the fuel reforming technology which facilitates the auto-ignition of hydrocarbon fuels in Homogeneous Charge Compression Ignition engines. The fuel used in this study was simulated biogas which contained 67% CH4 and 33% CO2 by volume. Investigations were made into HCCI feasibility using inlet heating alone, HCCI feasibility using inlet heating and addition of simulated reformed fuel, feasibility of H2 production using fuel reforming and a full closed loop test including on-line H2 production. All HCCI results were compared to spark ignition baseline results. HCCI combustion for biogas shows significant improvement in NOx emissions and efficiency over SI combustion. However, it is difficult to achieve with biogas and was only stable with both reformed fuel addition and intensive inlet heating.

12

Latest Devonian conodonts from an olistolith in the northern part of the Góry Bardzkie, West Sudetes

Haydukiewicz J.

Geologia Sudetica

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1998

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Vol. 31, nr 1

61-68

EN

Latest Devonian conodonts have been recovered from siliceous rock at Bardo Śląskie, Góry Bardzkie (Mts), West Sudetes. The exposure in the Nysa Kłodzka river cut consists of several undisturbed intervals, separated by zones of fault breccia, interpreted as one large olistolith of Devonian rock embedded in a surrounding Lower Carboniferous graywacke. The siliceous rock shows signs of very low-grade contact metamorphism (300-360°C; conodont CAI = 5) attributed to the late Carboniferous granite intrusion. They represent intervals from Mid- to probably Late-expansa Zone, Mid-expansa to the Early-praesulcata Zones and undivided praesulcata-Zone, all suggesting the latest Famennian age for the siliceous host rocks, which appear the youngest Devonian sediments paleontologically documented to date in the allochthonous domain of the Góry Bardzkie. Palmatolepis and Polygnathus are the most frequent genera. The two genera are believed to indicate the deepest pelagic environment of the late Devonian sea. Both the biofacies and lithofacies of the investigated sediments strongly suggest their distal, deep-water basinal origin. The presence of the open-marine pelagic sediments in the uppermost Famennian seems to imply a continuous sedimentation rather, than a break at the Devonian-Carboniferous boundary in the Góry Bardzkie allochthonous domain.