References of "Kedziora, Slawomir 50002079"
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See detailAUSLEGUNG eines BIOMECHANISCHEN TESTSTANDES für das BECKEN einschließlich der MUSKELKRÄFTE des GANGZYKLUS
Soliman, Ahmed Abdelsalam Mohamed UL; Ricci, Pierre-Louis; Kedziora, Slawomir UL et al

Scientific Conference (2022, October 28)

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See detailBiomechanische Untersuchung zu verschiedenen Verfahren der Stabilisierung von Insuffizienzfrakturen des vorderen Beckenringes
Gerich, Torsten; Soliman, Ahmed Abdelsalam Mohamed UL; Ricci, Pierre-Louis et al

Poster (2022, October 26)

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See detailDESIGN OF BIOMECHANICAL TESTING DEVICE FOR THE PELVIS INCLUDING GAIT MUSCLE FORCES
Soliman, Ahmed Abdelsalam Mohamed UL; Ricci, Pierre-Louis; Kedziora, Slawomir UL et al

Scientific Conference (2022, June 27)

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See detailAnalysis of residual stress relaxation of aluminum alloys EN AW 6061/-82 T6 under cyclic loading
Repplinger, Christian UL; Sellen, Stephan UL; Kedziora, Slawomir UL et al

in Fatigue and Fracture of Engineering Materials and Structures (2021)

Stress relaxation describes the reduction of stress under static or cyclic loading at a constant strain level. Several processes induce intentionally residual stresses, for example, autofrettage of thick ... [more ▼]

Stress relaxation describes the reduction of stress under static or cyclic loading at a constant strain level. Several processes induce intentionally residual stresses, for example, autofrettage of thick-walled pressurized tubes to improve their fatigue life. This well-known process induces residual compressive stresses at the critical inner surface by using a single static but controlled over- loading internal pressure. Relaxation of residual stresses due to cyclic loading in service would endanger the effectiveness of autofrettage and could finally lead to unexpected fatigue failure. In this study, strain-controlled experiments up to 500,000 load cycles and amending nonlinear finite element simulations were done for the aluminum alloys EN AW 6061 T6 and EN AW 6082 T6 to study potential cyclic stress relaxation in four-point bending tests after con- trolled single static plasticization for residual stress generation. This analysis identifies almost stable residual stresses for both materials under different cyclic strain-controlled load levels. [less ▲]

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See detailINVESTIGATING THE INFLUENCE OF PERSONALIZED MUSCULOSKELETAL MODELS ON THE CALCULATED STRESSES IN THE PELVIC RING
Soliman, Ahmed Abdelsalam Mohamed UL; Kedziora, Slawomir UL; Kelm, Jens et al

Poster (2021, September)

This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All ... [more ▼]

This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All calculated forces are utilized to predict stress states in pelvis bones using Finite Element (FE) software. Customized MS models provides more precise muscle and contact forces. Additionally, it enables more automatic coupling between MS and FE environments by data transfer. [less ▲]

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See detailInvestigating the influence of personalized musculoskeletal models on the calculated muscles and joints forces
Soliman, Ahmed Abdelsalam Mohamed UL; Kedziora, Slawomir UL; Kelm, Jens et al

Poster (2021, July)

It was the objective to analyze the influence of personalization of musculoskeletal models (MS) on muscle and contact joint forces for frequent daily movements. For normal gait cycle, we detect ... [more ▼]

It was the objective to analyze the influence of personalization of musculoskeletal models (MS) on muscle and contact joint forces for frequent daily movements. For normal gait cycle, we detect approximately 20% for some muscles attached to the pelvis, as well as for maximum hip-joint contact force. [less ▲]

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See detailPractical Implementation of Functionally Graded Lattice Structures in a Bicycle Crank Arm
Decker, Thierry UL; Kedziora, Slawomir UL; Wolf, Claude UL

in 850th International Conference on Science, Technology, Engineering and Management (2020, November 25)

Functionally graded lattice structures (FGLS) were studied thoroughly for the past years, mostly focusing on specific synthetic tests in the context of additive manufacturing while rarely being actually ... [more ▼]

Functionally graded lattice structures (FGLS) were studied thoroughly for the past years, mostly focusing on specific synthetic tests in the context of additive manufacturing while rarely being actually applied outside of this specific domain. This paper examines a way to practically implement them in a commonly used appliance and study their potential for its improvement. A bicycle crank arm was chosen for this purpose, and a solid aluminium reference model (Shimano FC-R450-453) is used as a performance baseline. The novel design is composed of a hollow body containing a beam-based, non-stochastic, functionally graded lattice structure and is planned to be manufactured on a Markforged Metal X system using 17-4 PH stainless steel. It aims to increase the total stiffness under EN ISO 4210-8 norm loading conditions compared to the reference model while limiting mass and stress values to acceptable degrees. Two crank arm variants, containing a face-centred cubic (FCC) and re-entrant auxetic lattice respectively, are optimised by locally altering their beam radii in eight separate regions. The displacement at the load application point is minimised using Altair OptiStruct and HyperStudy. The reference crank, weighing 213g, exhibits a deflection magnitude of 7.1mm in the most demanding load case while the newly designed and optimised versions only showed displacements of 2.52mm (FCC lattice, 340g) and 2.58mm (re-entrant lattice, 339g) respectively. In addition, the stress distribution was significantly enhanced compared to the reference model, as the latter would not pass the fatigue tests required by the norm. This demonstrates that FGLS, in combination with high-strength materials and additive manufacturing, can increase the performance of many parts, although in this case, with a trade-off in terms of its mass. In future projects, it might be considerably reduced by utilising alternative lattice types lattices or other materials while preserving the benefits of FGLS. [less ▲]

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See detailNumerical Assessment of two Implants for Pubic Ramus Fracture of human Pelvis applying Normal Gait loading
Ricci, Pierre-Louis; Gerich, Torsten; Kelm, Jens et al

Poster (2020, October)

Fractures of the anterior pelvic ring reduce patients` mobility and independence and increase mortality. Pelvic instability impairs the load transfer to the lower extremity. Restoring stability has ... [more ▼]

Fractures of the anterior pelvic ring reduce patients` mobility and independence and increase mortality. Pelvic instability impairs the load transfer to the lower extremity. Restoring stability has therefore been a crucial point of research. Most of the reported studies refer to loading on one leg stand without consideration of physiological muscle and contact-joint forces of the common vital daily movements. Our present study considers physiological gait loading of all acting muscles and Hip Joint Contact (HJC) forces of the pelvis. Those muscles and HJC forces were calculated by inverse dynamics for normal gait motion data and applied in Finite Element Analyses (FEA). The biomechanical stability provided to the anterior pelvic ring by two reconstructive techniques was investigated numerically: the iliopubic Subcutaneous Plate (SP) and the Supra-Acetabular External Fixator (SAFE). Numerical biomechanical assessment of two reconstructive devices for pubic ramus fracture. All muscles and HJC forces of normal gait were calculated by means of inverse dynamics software for a healthy patient considering a musculoskeletal model previously validated experimentally. The Finite Element (FE) model was developed for a pelvis with and without superior and/or inferior rami fractures. Furthermore, two FE models for SP and SAFE mounted on the rami fractured pelvis were designed considering fixation bearing at the lumbosacral joint. The calculated forces were implemented on the FE models following the anatomical orientation and attachments/insertions of each muscle. During the two moments of the gait with higher stresses: Left Heel Strike (LHS) and Right Toe-Off (RTO), strains and displacements were recorded and investigated at the fracture location in addition to the implant fixation points. Considering only right superior ramus fracture during LHS and RTO, recorded strains and displacements for both implants showed similar results. However, during RTO, the SAFE showed a slight reduction of strains at the posterior location by 6% compared to SP. When including both superior and inferior right ramus fractures, both devices did not show considerable difference in recorded strains. However, there were significant differences in the displacements between fracture extremities. The SP technique reduced these motions for both LHS and RTO by 40% compared to the gold standard SAFE technique. In cases of superior ramus fracture only, displacements for both reconstructive devices were similar due to the remaining stability provided by the intact inferior ramus. Both devices reduced stresses of the sacrum wing in LHS and RTO with slightly better results for SAFE. In case of superior and inferior pubic ramus fractures, the SP technique reduced the frontal opening of the fractured right pubic bone. The SAFE did not provide any improvements compared to the SP technique. [less ▲]

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See detailOptimization assisted redesigning a structure of a hydrogen valve: the redesign process and numerical evaluations
Cao, Thanh Binh UL; Kedziora, Slawomir UL; Sellen, Stephan UL et al

in International Journal on Interactive Design and Manufacturing (2020)

This study introduced the redesign process of an automotive hydrogen valve. The process relied on the structural optimization approach, which used to build up the new valves having promising stiffness and ... [more ▼]

This study introduced the redesign process of an automotive hydrogen valve. The process relied on the structural optimization approach, which used to build up the new valves having promising stiffness and the lowest possible weights. To achieve the goals, the study was proposed to be taken place via the three main stages. These stages included topology optimization, lattice optimization, as well as numerical evaluations. The achieved results firstly indicated that the two newly designed valves possessed longer life and lower mass than the original valve. Especially, the topology optimized one could withstand more than 5E4 working cycles in the pre-treated condition before the first crack would be nucleated. The results also pointed out the influences of the pre-treatment pressure on the fatigue performance of the hydrogen valve. Within the examined ranges of the pressure, increasing the pressure’s magnitudes tended to shorten the fatigue life of the topology optimized valve. Additionally, the results highlighted the impact of the employed materials on the estimated fatigue life of such a non-treated structure. In the highlights, the considered steel valves could function normally far beyond 1.5E5 working cycles while the aluminum valves would have an initial crack formation prior to reaching 3E3 cycles. The results also suggested that further practical evidence is needed to not only confirm whether the selected printed aluminum is among the promising candidate materials of the hydrogen valve but also to support the described evaluations. [less ▲]

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See detailOptimum Autofrettage Pressure of Hydrogen Valve Using Finite Element and Fatigue Analysis
Kedziora, Slawomir UL; Cao, Thanh Binh

in Engineering (2020), 12(01), 1--24

The presented article shows an estimation method of optimum autofrettage pressure taking into consideration subsequent cyclic loading. An autofrettage process is used in pressure vessel applications for ... [more ▼]

The presented article shows an estimation method of optimum autofrettage pressure taking into consideration subsequent cyclic loading. An autofrettage process is used in pressure vessel applications for strength improvement. The process relies on applying massive pressure that causes internal portions of the part to yield plastically, resulting in internal compressive residual stresses when pressure is released. Later applied working pressure (much lower than autofrettage pressure) creates stress reduced by the residual compressive stress improving the structural performance of the pressure vessels. The optimum autofrettage pressure is a load that maximizes the fatigue life of the structure at the working load. The estimation method of that pressure of a hydrogen valve is the subject of the presented work. Finite element and fatigue analyses were employed to investigate the presented problem. An automated model was developed to analyze the design for various autofrettage pressures. As the results of the procedure, the optimum autofrettage pressure is determined. The research has shown that the developed method can profitably investigate the complex parts giving the autofrettage load that maximizes the fatigue life. The findings suggest that the technique can be applied to a large group of products subjected to the autofrettage process. [less ▲]

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See detailDesigning an early failure indicator channel for an in-tank hydrogen valve via a fatigue-based approach
Cao, Thanh Binh UL; Kedziora, Slawomir UL; Sellen, Stephan et al

in Journal of Computational Design and Engineering (2020)

This study introduced a fatigue-based approach to design and implement an indicator channel into an in-tank hydrogen valve. It was aimed at providing a mean to point out multiple early valve’s damages. To ... [more ▼]

This study introduced a fatigue-based approach to design and implement an indicator channel into an in-tank hydrogen valve. It was aimed at providing a mean to point out multiple early valve’s damages. To achieve the goal, the study was proposed to handle via three main phases. They included (i) the risk point determinations, (ii) the new valve design and the crack nucleation life estimations, as well as (iii) the simplified crack growth analyses. The obtained results firstly highlighted the construction of the test channel (TC), whose branches were located close to the predicted damage’s sites. The damages could be identified either when a crack reaches the TC (then forms a leakage) or indirectly via the crack propagations’ correlation. The results also pointed out that the TC-implemented valve could perform as similarly as the non-TC one in the non-treated condition. More importantly, this new structure was proved to have a capacity of satisfying the required minimal life of 1.5E5 cycles, depending on the combined uses of the specific material and the pre-treatment, among those considered. In addition, the results emphasized the complexity of the TC that could not be formed by the traditional manufacturing process. Hence, direct metal laser sintering was proposed for the associated prototype and the final TC was issued based on the fundamental requirements of the technique. Finally, it was suggested that practical experiments should essentially be carried out to yield more evidence to support the demonstrated results. [less ▲]

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See detailNumerical determination and experimental verification of the optimum autofrettage pressure for a complex aluminium high-pressure valve to foster crack closure
Repplinger, Christian UL; Sellen, Stephan; Kedziora, Slawomir UL et al

in Fatigue and Fracture of Engineering Materials and Structures (2020)

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See detailThe Buckling and Post-Buckling of Steel C-Columns in Elevated Temperature
Czechowski, Leszek; Kedziora, Slawomir UL; Kolakowsk, Zbigniew

in Materials (2019), 13(74), 1-12

This work deals with the investigation of a steel thin-walled C-column subjected to compression due to temperature increase. These experimental studies of the compressed columns in post-buckling state ... [more ▼]

This work deals with the investigation of a steel thin-walled C-column subjected to compression due to temperature increase. These experimental studies of the compressed columns in post-buckling state were conducted to determine their load-carrying capacity. To ensure appropriate supports and keeping of columns, plates with grooves were constructed. The tests of the columns' compression for different preloads were carried out. By comparing the experiment results, numerical calculations based on the finite element method (FEM) and the semi-analytical method (SAM) of solution were performed. The computations were executed with the use of full material characteristics with consideration of large strains and deflections. Furthermore, while observing the deformation of columns, a non-contact Digital Correlation ARAMIS\textregistered system was employed whose calculated results of deformations are very close to the results of the numerical method. The paper revealed that maximum recorded loads under temperature rise are comparable regardless of a value of initial load. A good correlation in results between used methods was achieved. The main goal of the present work was to assess of behavior of thin-walled compressed steel columns in a temperature-controlled environment till their full damage [less ▲]

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See detailDesign of continuously variable bicycle transmission
Kolb, Jean; Kedziora, Slawomir UL

Report (2019)

As the people’s needs develop, so does the technology. Bicycles exist already for a long time, and ever since the appearance of electrically driven ones, the necessity to change their drivetrain and ... [more ▼]

As the people’s needs develop, so does the technology. Bicycles exist already for a long time, and ever since the appearance of electrically driven ones, the necessity to change their drivetrain and transmission started getting more important. What makes the development of bicycles even more impressive is the fact that their efficiency ranks first among travelling animals and machines, if we consider the energy consumed by moving a certain distance as a function of body weight. Different bicycle drivetrains are researched and explained in this report, especially CVT hubs. A continuously variable transmission based on a patent of Hiroyuki Urabe has been designed with the CAD method, and their main parts were analysed using the FEA method. The final construction has a theoretical total ratio of 400% and a mass of about 2.7kg (without lubricant). This transmission is using the principles of frictional traction to transfer torque. In general, this work shows how the designing process proceeded and gives an idea, how this type of gearbox could be constructed. [less ▲]

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See detailInnovative designs of an in-tank hydrogen valve towards direct metal laser sintering compatibility and fatigue life enhancement
Cao, Thanh Binh UL; Kedziora, Slawomir UL

in Structural and Multidisciplinary Optimization (2019)

Replacements of using fossil fuel by different types of renewable energy are the current development trend in the automotive industry towards sustainable vehicles. A hydrogen-powered car is a promising ... [more ▼]

Replacements of using fossil fuel by different types of renewable energy are the current development trend in the automotive industry towards sustainable vehicles. A hydrogen-powered car is a promising solution, in which the safe and smooth operation of the car is strongly depended on how an in-tank valve of a fuel-storage-system performs. The present paper introduces the investigations and innovations of structures of the mentioned valve, whose designs can be subjected to fabricate by direct metal laser sintering. Two parts of the valve were taken into considerations, including the largest female-thread and the body. While the threads were investigated in the proposed conditions via fatigue-life assessment, the bodies were only assessed after being built from the concepts, developed by structural optimisations and lattice implementation. The achieved results showed that within the same pre-treated conditions, the optimised valves have considerably higher fatigue life, but lower masses, than those of the original. It was also observed that the applications of pre-treatment by autofrettage could contribute significantly to life prolongation of the valves as compared to the non-treated ones. In addition, those essential features, such as powder-release channels, which make the developed valves compatible with DMLS, were implemented into the valve-designs to be able to ensure their successful prints. Finally, the results suggested that the second innovated structure of the lattice-valve is the best candidate, which could be additively produced for the upcoming experimental-validation phase of the demonstrated works. [less ▲]

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See detailMaterials, valves and sealing gaskets for high pressure applications
Repplinger, Christian UL; Sellen, Stephan; Kedziora, Slawomir UL et al

Poster (2019)

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See detailUpcycling polymers: a revolutionary approach to promoting the circular economy
Wolf, Claude UL; Kedziora, Slawomir UL

in Impact (2018), 2018(Number 9), 103-1053

The UPcycling using Additive Manufacturing (UpAM) project seeks to introduce an innovative educational and interactive framework to demonstrate the benefits of upcycling so that any individual can produce ... [more ▼]

The UPcycling using Additive Manufacturing (UpAM) project seeks to introduce an innovative educational and interactive framework to demonstrate the benefits of upcycling so that any individual can produce their own products using recycled raw materials. For years, societies have been aware that the unlimited consumption of products is unavoidably intertwined with the unlimited production of waste. This is exactly why scientists and researchers have been trying to find alternative and meaningful solutions to the Linear Economy model, a model that dictates a specific sequence of events: extracting raw materials, manufacturing products, consuming and discarding these products. Looking beyond that ‘take, make, dispose’ approach, it was in 1989 that the notion of Circular Economy (CE) was first proposed by Pearce and Turner; a concept that is restorative and regenerative and that involves reusing products, repairing, recycling and upcycling. Therefore, the core element of this innovative and environmentally-friendly model is to rely on system-wide innovative processes in order to redefine products, services and, most importantly, our way of thinking, to design waste out, thus allowing a profound transition to renewable energy sources [less ▲]

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See detailConcrete-Filled Steel Tubular (CFTS) Columns Subjected to Eccentric Compressive Load
KEDZIORA, SLAWOMIR UL; Anwaar, Muhammad Omer

in AIP Conference Proceedings (2018, November 15)

Concrete-steel composite structures are very efficient in carrying high loads as they combine benefits of both materials concrete and steel. The combination of them can significantly improve the strength ... [more ▼]

Concrete-steel composite structures are very efficient in carrying high loads as they combine benefits of both materials concrete and steel. The combination of them can significantly improve the strength of the composite structure by taking advantage of high compression resistance of concrete and high strength of steel in tension. Recently, there has been renewed interest in the composite structures used in different forms, as beams, slabs, sandwich structures and columns and many methods of structural analyses were utilised. However, none of them was able to eliminate concrete material when it fractured. The presented work concerns circular composite columns CFST under eccentric compression. The principal objective of the project was to investigate a straightforward method based on a finite element analysis employed to estimate the load carrying capacity of columns. This study has also been set out to determine whether the Drucker-Prager material model of concrete without a crack capability could be used for analyses of the CFST columns with the additional elimination of the concrete material when concrete is damaged. The elaborated finite element model was verified with existing test data from the literature. The findings show that the correlation between the test results and the numerical analysis was excellent confirming the feasibility of usage of the proposed method for the assessment of complex cases of the CFST columns. A new part of the work is the employment of a death element feature to eliminate concrete material, which theoretically is not taking any load after reaching its tensile strength. A criterion to eliminate elements from the model is the maximum principal stress greater than tensile strength. The obtained results are excellent; the established goal was met entirely. [less ▲]

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See detailDetermination of the optimum autofrettage pressure for a complex aluminum valve body
Repplinger, Christian UL; Sellen, Stephan; Kedziora, Slawomir UL et al

Scientific Conference (2018)

Detailed reference viewed: 73 (11 UL)