Wyniki wyszukiwania - BazTech

1

Biomechanical analysis of diversified screw arrangement on 11 holes locking compression plate considering time-varying properties of callus

Sepehri B., Taheri E., Ganji R.

Biocybernetics and Biomedical Engineering

|

2014

|

Vol. 34, no. 4

220--229

EN

The 11 holes locking compression plate (LCP) is a type of fixator which is currently used in orthopedic surgeries for fixing fractures of long bones. 8 styles of screw positioning on this plate are possible so each orthopedist may use one of them during operations. The aim of the current study was the analysis of diversified screw arrangement on the mentioned LCP for fixation of medial transverse fracture of tibia considering time- varying properties of bone callus in 16-weeks curing duration. Stress shielding effects were also considered. Finite element method using Mimics 10.01, Solid works 2012 and Abaqus 6.11-1 software have been applied. Modeling of bone was done based on computer tomography (CT) scan of human right tibia and four types of forces have been loaded on intact bone and the same was loaded on fixated fractured ones in 8 treatments of fixation. Stresses in bone, plate and screws, also gap or callus strains and stiffnesses in 5 terms of curing duration in all of the treatments have been investigated and compared together using new defined parameters. Finally the preferred treatment was concluded. Results of this study may be used by orthopedists in applying such a fixator for fixation of tibia and other fractured long bones.

2

Biomechaniczna analiza wypadku samochodowego z zastosowaniem urządzenia typu HANS podpierającego głowę oraz odcinek szyjny kręgosłupa kierowcy

Burkacki M., Joszko K., Gzik M.

Aktualne Problemy Biomechaniki

|

2013

|

z. 7

17--22

PL

Celem pracy było dokonanie analizy w środowisku MADYMO wypadku samochodu rajdowego z zastosowaniem urządzenia HANS podpierającego głowę oraz odcinek szyjny kręgosłupa kierowcy. Stworzono model odzwierciedlający warunki panujące w samochodzie rajdowym, który został użyty do symulacji zderzenia przy przyspieszeniu 45G. Na podstawie otrzymanych wyników można stwierdzić, iż system HANS ogranicza urazowość głowy oraz odcinka szyjnego kręgosłupa podczas wypadku. Wpływa on na zmniejszenie siły działającej na odcinek szyjny kręgosłupa, ugięcie w odcinku szyjnym kręgosłupa oraz ugięcie klatki piersiowej.

EN

The aim of this study was to analyze a rally car accident in MADYMO software with use of the HANS device supporting head and cervical spine of the driver. Created model reflects the construction and equipment of a rally car which was used to simulate a 45G accident. Based on the results it can be said that the HANS system reduces trauma of the head and cervical spine during accident. It also reduces force affecting cervical spine, deflection of the cervical spine and chest deflection.

3

Analiza biomechaniczna obciążenia w kończynie dolnej podczas jazdy konnej

Sobuś M., Iwaniec M., Frontczak A., Łagan S.

Aktualne Problemy Biomechaniki

|

2011

|

z. 5

137--142

PL

W niniejszym referacie podjęto próbę analizy wpływu długości strzemion w jeździe konnej na obciążenia powstające w kończynie dolnej. Wraz ze zmianą długości strzemion zmienia się kąt zgięcia nogi w stawie kolanowym oraz skokowym.

EN

In this publication we would like to analyse how length of the stirrups effects on loads in the lower limb. The longer stirrups are the bigger knee and ankle angles are. In horse riding there are some kinds of rider‟s positions, which are connected with discipline. Dressage rider„s seat is different than jumping or race seat, so we would like to analyse these differences. For example the long stirrups of the dressage rider allow for a long leg. But the short stirrups of a jockey allow the rider to stay over the galloping horse's center of balance and allow the horse to reach the maximum possible speed.

4

Numerical and experimental analysis of spine’s transpedicular stabilizer

Kiel M., Marciniak J., Basiaga M., Szewczenko J., Kus W., Kokot G., Wadek T.

Journal of Achievements in Materials and Manufacturing Engineering

|

2010

|

Vol. 41, nr 1-2

124-130

EN

Purpose: The aim of the work was a numerical and experimental analysis of spine’s transpedicular stabilizer on lumbar part of spine. The result of the analysis was determination of displacements of the stabilizers’ elements. Design/methodology/approach: To define numerical characteristic of the lumbar spine – transpedicular spine stabilizer system, the finite element method was applied. Geometrical models of lumbar part of spine and transpedicular stabilizer were discretized by SOLID95 element. The boundary conditions imitating phenomena in real system with appropriate accuracy were established. The experimental analysis was carried out for spine’s transpedicular stabilizers which were implanted on lumbar part of pig spine. The analysis was realized by means of testing machine MTS Insight with the use of videoextensometer. Numerical and experimental analysis were carried out for stabilizer made of stainless steel Cr-Ni-Mo. System was loaded by uniaxial compression with forces from 50 N to 1600 N. Findings: The result of analysis was calculation of relative displacements of the transpedicular stabilizer in a function of the applied loading; F = 700 - 1600 N for numerical model and F = 50 - 1600 N for experimental model. Research limitations/implications: The results of numerical analysis for transpedicular stabilizer obtained by finite element method were used to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial. The calculation of displacements for stabilizer show that the proposed type of stabilizer enables correct stabilization of spine. Practical implications: Both results of numerical and experimental analysis showed correct selection of mechanical properties of metallic biomaterial which were used to made the proposed type of transpedicular stabilizer. Originality/value: Advantageous results of analysis showed that the type of stabilizer may be used in clinical practice.

5

FEM used in improvement of quality of medical devices

Ziębowicz B., Ziębowicz A., Szkodny J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2010

|

Vol. 41, nr 1-2

172-179

EN

Purpose: The fundamental aim of this research was to determine the biomechanical characteristics of the medical bed made of carbon steel and an assessment of its stability. To define the biomechanical characteristics of the bed design, the finite element method (FEM) was applied. Additionally, the risk analysis was conducted according to the directives of ISO 14971 standard. Design/methodology/approach: The research was carried out on the typical rehabilitation bed. To define the biomechanical characteristics of this equipment, the finite element method was applied. Geometric model of medical bed, was discretized by means of SOLID 95 element. Appropriate boundary conditions imitating phenomena in the real system with appropriate accuracy were established. The aim of biomechanical analysis was calculation of displacements and stresses in the bed’s construction elements in a function of the applied loading. In order to carry out calculations, 3 models of diverse variants of loading were selected – safe working load - model 1, transverse stability - model 2 and longitudinal stability - model 3. Findings: The analyses showed the difference in displacements, strains and stresses in the characteristic points depending on the selected loading. That also helped to determine maximal loading causing the exceeding of the yield stress of the bed’s components. Research limitations/implications: The limitations were connected with simplification of numerical model of femur as well as with the selected boundary conditions. Practical implications: The obtained results can be useful in the designing process (modification of requirements regarding design and construction, as well as materials used in the production of the device, and reduction of risk as far as possible to the patient). They prove that 3D geometrical analysis works quite well for assistive medical devices design. Originality/value: Stress-strain-displacement characteristics of the medical bed’s elements, obtained from the numerical analysis were presented in the work.

6

Analiza biomechaniczna ryglowanego zespolenia śródszpikowego kości udowej

Kajzer W., Kajzer A., Szewczenko J., Marciniak J.

Engineering of Biomaterials

|

2010

|

Vol. 13, no. 96-98

54--57

7

Expandable intramedullary nail – experimental biomechanical evaluation

Kajzer A., Kajzer W., Marciniak J.

Archives of Materials Science and Engineering

|

2010

|

Vol. 41, nr 1

45-52

EN

Purpose: The paper presents results of experimental analysis of femur and femur - expandable intramedullary nail system. The aim of the work was to determine displacement in three models. In addition, the torsion of the system aiming at determining the moments depending on the torsional angle of the bone was carried out. Design/methodology/approach: Three femurs were selected for studies. The analysis was carried out on the femur - expandable intramedullary nail system. The influence of the loads and displacements on the bone - nail system on the results of experimental analysis was analysed. In order to carry out calculations, three models were selected: model I - bone without fracture gap, model II and III - femur with expansion intramedullary nails - fracture gap was located 100 mm under greater trochanter. The studies were performed on femur models produced by Swedish company Sawbones. The intramedullary "Fixion IM" nails (Ti-6Al-4V alloy) were implanted into the bone. Displacements of determinated models were being recorded from the sensors every 100 N from 10 N to 2000 N. Findings: The analyses showed the difference in displacements, depending on the selected models. Research limitations/implications: The limitations were connected with simplification of boundary conditions during analysis which were the result of the simplification of the models. While studying, muscles and ligaments supporting the bone in anatomic position were not taken into consideration. Instead, the system has been loaded with the axial force (compression). Practical implications: The obtained results can be useful in clinical practice. They can be applied in selection of stabilization methods or rehabilitation as well as in describing the biomechanical conditions connected with type of bone fracture obtained from medical imaging. Originality/value: . The work compares the values of displacement of characteristic points of femur (healthy - model I) with the femur - expandable intramedullary nail system (models II and III) with the applied force. In order to estimate the value of the torsional angle of the upper part in relation to the lower one depending on the applied force, the torsion of the model was conducted. On this basis, it was indicated a maximum moment in which the nail would not become loose in medullar canal.

8

Eksperymentalna i numeryczna analiza biomechaniczna stentu wieńcowego typu slotted-tube

Pochrząst M., Walke W., Kaczmarek M.

Aktualne Problemy Biomechaniki

|

2010

|

z. 4

151--156

PL

Zasadniczym celem prezentowanej pracy było wyznaczenie charakterystyki biomechanicznej stentu naczyniowego wykonanego ze stali Cr- Ni-Mo. W celu wyznaczenia charakterystyki wytrzymałościowej analizowanej postaci stentu zastosowano metodę elementów skończonych. Wyznaczone w trakcie analizy wartości odkształceń poszczególnych elementów stentu wskazują, że jedynie zastosowanie warstwy powierzchniowej podatnej do odkształceń w trakcie zabiegu implantacji skutecznie ogranicza reaktywność powierzchni stentu w środowisku krwi.

EN

The aim of the work was determination of biomechanical characteristics of vascular, stainless steel stent. In order to determine strength characteristics of the analyzed stent, the finite element method was applied. Strains calculated for individual elements of the stent indicate that only application of deformable surface layer efficiently reduces reactivity of the stent in blood environment.

9

Biomechaniczna analiza wchodzenia na schody oraz badania stabilograficzne pacjentów z zaburzeniami neurologicznymi

Tejszerska D, Michnik R, Jurkojc J, Guzik-Kopyto A, Michalik K, Kmiotek A, Rycerski W

Aktualne Problemy Biomechaniki

|

2010

|

z. 4

249--254

PL

W pracy przedstawiono biomechaniczną analizę wchodzenia po schodach oraz badania stabilograficzne pacjentów ze schorzeniami neurologicznymi. W badaniach analizowano kinematykę oraz wartości sił reakcji podłoża podczas wchodzenia po schodach. Wielkości kinematyczne wyznaczono za pomocą systemu APAS. Pomiarów sił reakcji podłoża dokonano za pomocą platform dynamometrycznych firmy Kistler. Badania doświadczalne objęły grupę 8 osób z zaburzeniami neurologicznymi. Badania zrealizowano w Górnośląskim Centrum Rehabilitacji w Reptach.

EN

Biomechanical analysis of climbing the stairs and stability of patients having neurological disorders is presented in the paper. Analysis of kinematics and ground reactions was carried out for climbing the stairs. Kinematic quantities were determined by means of the APAS system. Ground reactions were measured with the use of the Kistler platform. Eight patients took part in the research. All measurements were carried out in the Silesian Center of Rehabilitation “Repty”.

10

Analiza biomechaniczna odcinka szyjnego kręgosłupa człowieka w sytuacji zastosowania stabilizacji

Wolański W., Tejszerska D.

Modelowanie Inżynierskie

|

2009

|

T. 7, nr 38

295-300

PL

W pracy przedstawiono model odcinka szyjnego kręgosłupa człowieka sformułowany metodą elementów skończonych. Opracowany model MES posłużył do biomechanicznej analizy kręgosłupa szyjnego po przedniej stabilizacji. Prezentowane wyniki przedstawiają zachowanie się trójwymiarowego modelu odcinka szyjnego kręgosłupa pod wpływem różnych fizjologicznych obciążeń. Badania te posłużyły do pogłębienia wiedzy o biomechanice odcinka szyjnego kręgosłupa człowieka w sytuacji zastosowania stabilizacji. Przedstawione modele mogą być również użyte do analizy klinicznych problemów dotyczących kręgosłupa szyjnego człowieka.

EN

Described in the paper is the model of cervical spine formulated using finite element method. This FE model was developed to biomechanical analysis of the cervical spine stabilisation. The present results demonstrates behaviour of three-dimensional model of cervical spine under various physiological loads. The investigations was used to understanding the biomechanics of the cervical spine when stabilisation was applied. Presented models can also be used to analyse the clinical problems concerning biomechanics of human cervical spine.

11

FEM analysis of expandable intramedullary nails in healthy and osteoporotic femur

Kajzer W., Kajzer A., Marciniak J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 37, nr 2

563-570

EN

Purpose: The paper presents the results of numerical analysis of expandable intramedullary nail – femur system in different states of healing. The aim of the research was to determine displacements, deformations and stresses occurring in a bone depending on the age of the patient and the extent level of osteoporosis. Design/methodology/approach: A femur was selected to numerical analysis. The analysis concerned the influence of the load and torsion of the system on the obtained results of displacements, deformations and reduced stresses. In order to make calculations, four models with different mechanical properties were chosen: model 1: femur with mechanical properties corresponding with a femur of a patient at the age of 16, model 2: with mechanical properties corresponding with a femur of a patient at the age of about 28, model 3: with mechanical properties corresponding with a femur of a patient at the age of about 20 and at the age of 50 to 65 years old and model 4: with mechanical properties corresponding with a femur of a patient at the age above 70 or with osteoporosis. For the chosen model of intramedullary nail, mechanical properties of titan alloy Ti-6Al-4V were used. Two load steps were analyzed: load step 1 in which simple axial load with a value ranging from 250 up to 1000 N simulating patient standing on one leg was used, and load step 2 – a torsion analyzing loads that the nail is exposed to while walking. Findings: Conducted analysis of the system showed the difference in displacements, deformations and reduced stresses depending on assumed mechanical properties of femur and load step of the system. Research limitations/implications: The limitations were connected with the necessity of simplifying the assumptions, which were associated with limitations caused by boundary conditions. In researches 4 forces loading the femur axially were used: 1: force F = 250N, 2: with force F = 500N, 3: with force F= 750N and 4: with force F = 1000N and 5 values of angle displacement of the femur head were assumed: 1: angle displacement ö = 1°, 2: ö = 5°, 3: ö = 10°, 4: ö = 15°, 5: ö = 20°. Practical implications: Obtained results can be applied in selection of stabilization methods of bone fragments and in forecasting biomechanical conditions depending on the age of patient and the state of his general conditions of bones. Originality/value: The paper presents the displacement-deformation-stress characteristics of femur - expandable intramedullary nail system, using the Finite Elements Method (FEM) in the analysis.

12

FEM analysis of compression screws used for small bone treatment

Kajzer W., Kajzer A., Marciniak J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2009

|

Vol. 33, nr 2

189-196

EN

Purpose: The paper presents results of numerical analysis in metatarsal bone „I” - compression screws system. The aim of the work was determined stresses, strain and displacement in the inserted screws. Design/methodology/approach: Metatarsal bone „I” was selected to researches. The analysis was carried out on the metatarsal bone „I” - compression screws system. The influence of the loads and displacements on the bone - screws system on the results of numerical analyses was analyzed. In order to carry out calculations, 2 models of diverse mechanical properties of screw - Ti-6Al-4V alloy - model 1, stainless steel (Cr-Ni-Mo) - model 2 and two load steps were selected. Findings: The analyses showed the difference in displacements, strains and stresses depending on the selected mechanical properties screws and the way of loads. Research limitations/implications: The limitations were connected with simplification of numerical model of femur as well as with the selected boundary conditions. Two difference way of loads metatarsal bone „I” - compression screws system: 1_force F = 500 N, 2_ displacement l = 1 mm were applied. Practical implications: The obtained results can be useful in clinical practice. They can be applied in selection of stabilization methods or rehabilitation as well as in describing the biomechanical conditions connected with type of bone fracture obtained from medical imaging. Originality/value: Stress-strain-displacement characteristics of metatarsal bone „I” - compression screws system, obtained from the numerical analysis were presented in the work.

13

Analiza biomechaniczna zespolenia kość śródstopia I - śruby dwuwchodowe

Ziębowicz A., Kajzer A., Kajzer W., Marciniak J.

Engineering of Biomaterials

|

2009

|

Vol. 12, no. 89-91

249--251

14

Biomechanical analysis of plate stabilization on cervical part of spine

Kiel M., Marciniak J., Szewczenko J., Basiaga M., Wolański W.

Archives of Materials Science and Engineering

|

2009

|

Vol. 38, nr 1

41-47

EN

Purpose: The main aim of the work was determination of biomechanical analysis of cervical spine – stabilizer system made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy. Design/methodology/approach: To define biomechanical characteristic of the system the finite elements method (FEM) was applied. Geometric model of part of spine C5-C7 and stabilizer were discretized by SOLID95 element. Appropriate boundary conditions imitating phenomena in real system with appropriate accuracy were established. Findings: The result of biomechanical analysis was calculation of displacements and stresses in the vertebras and the stabilizer in a function of the applied loading: 50-300 N for the stabilizer made of stainless steel (Cr-Ni-Mo) and Ti-6Al-4V alloy. Research limitations/implications: The result of biomechanical analysis for plate stabilizer obtained by FEM can be use to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial and estimation of stabilization quality. The calculation of displacements for part C5-C7 show that the proposed type of stabilizer enables correct stabilization used to clinical apply. Practical implications: The results of biomechanical analysis showed correct mechanical properties used to made the plate stabilizer. Originality/value: The obtained numerical results should be verified in “in vitro” tests.

15

Analiza biomechaniczna układu wiertło chirurgiczne - kość udowa

Paszenda Z., Basiaga M.

Aktualne Problemy Biomechaniki

|

2009

|

z. 3

181--186

PL

Zasadniczym celem prezentowanej pracy była analiza biomechaniczna układu wiertło chirurgiczne - kość udowa w warunkach symulujących proces wiercenia w kości. Opracowano model geometryczny wiertła chirurgicznego o zróżnicowanej geometrii ostrza (2κ1 = 90° i 2κ2 = 120°) oraz krążka symulującego kość udową. Obliczenia przeprowadzono dla wiertła wykonanego ze stali X39Cr13. Efektem zrealizowanej analizy było wyznaczenie stanu odkształceń i naprężeń zredukowanych w części roboczej wiertła w funkcji obciążenia siłą F = 20-100 N i prędkością obrotową n = 2000 obr/min.

EN

The aim of the work was determination of biomechanical analysis of a surgical drill - bone system in simulated conditions of drilling in a bone. Geometrical models of the surgical drill of diverse geometry of the edge (2κ1 = 90° and 2κ2 = 120°) and the disc simulating femur were worked out. Calculations were carried out for the drill made of martensitic Steel (X39Cr13). The effect of numerical analysis was determination of strains and stresses in working part of the drill as a functional of the applied loading F = 20-100 N and rotational speed n = 2000 rpm.

16

Numerical analysis of femur in living and dead phase

Krauze A., Kaczmarek M., Marciniak J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

|

Vol. 26, nr 2

163-166

EN

Purpose: The paper presents numerical analysis results of stresses and displacement in femur in a living and a dead phase. The aim of the work was to present the influence of different mechanical properties of bone tissue on the obtained results. The appropriate selection of the properties ensures correct results, comparable with the results obtained in real conditions. Design/methodology/approach: The analysis was carried out on the femur of adult. The influence of the selected properties on the results of numerical analyses was analyzed. In order to carry out calculations, 3 models of diverse mechanical properties (Young modulus of bone in a living phase EI=17260 MPa, Young modulus in order to carry out a comparison analysis EII=18600 MPa and Young modulus of bone in a dead phase EIII=20202 MPa) were selected. Findings: The analyses showed the difference in displacements and reduced stresses depending on the selected mechanical properties. The analyses show that in order to select the appropriate stabilization method, mechanical characteristics of bone structures should be considered as viscoelastic. Quality of bone structures depends on individual features (genetic, hormonal, metabolic and circulatory factors). Research limitations/implications: The limitations were connected with simplification of numerical model of femur as well as with the selected boundary conditions. Practical implications: The obtained results can be useful in clinical practice. They can be applied in selection of stabilization methods or rehabilitation as well as in describing the biomechanical conditions connected with type of bone fracture obtained from medical imaging. Originality/value: Stress-displacement characteristics of femur for different degrees of demineralization, obtained from the numerical analyses were presented in the work.

17

Stabilizacja stawu barkowego wg koncepcji metody Bobath u osób z niedowładem połowiczym po udarze mózgu - analiza biomechaniczna

Borkowska A., Dobrowolna P., Hagner W.

Aktualne Problemy Biomechaniki

|

2008

|

z. 2

19--26

PL

Terapia pacjentów z niedowładem połowiczym po udarze mózgu powinna przebiegać według ustalonych zasad, bezboleśnie i prowadzić do uzyskania jak największej funkcjonalności m.in. kończyny górnej. Przeprowadzona analiza biomechaniczna ma na celu zwrócenia szczególnej uwagi na pozycje stawu barkowego podczas coraz częściej stosowanych ćwiczeń wg koncepcji metody Bobath. Potwierdza również słuszność i ważność stabilizacji barku poprzez aproksymację w okresie wiotkim porażenia, aby zapobiegać jego podwichnięciu i bolesności, co utrudniłoby a nawet uniemożliwiłoby proces usprawniania.

EN

Therapy of patients with hemiparesis after cerebral stroke should be conducted due to strict methods, in painless manner leading to the highest possible functionning of upper limb. The aim of biomechanical analysis was to pay attention on shoulder joint positions during commonly used exercises based on Bobath method. Analysis also confirmed significance and importance of shoulder joint stabilization by approximation during limp period of paralysis to prevent pain and sprain which can make the rehabilitation impossible.

18

Porównawcza analiza biomechaniczna wybranych systemów stabilizacji transpedikularnej

Sajewicz E., Koronkiewicz T., Sidun J.

Acta Mechanica et Automatica

|

2008

|

Vol. 2, no. 1

69-72

PL

Prezentowane w pracy wyniki dają odpowiedź na pytanie dotyczące wpływu podatności lędźwiowego odcinka kręgosłupa na jakość stabilizacji transpedikularnej. Przedstawiono wyniki badań przemieszczeń odcinka lędźwiowego kręgosłupa poddanego jednocześnie kompresji i zginaniu (mimośrodowe ściskanie). Badano przemieszczenia kręgu L3 dziewięciu preparatów ustabilizowanych za pomocą systemów Socon, Omega oraz Bial-Stab, a następnie pomiary powtarzano po wykonaniu korporektomii na poziomie L3. Wyniki badań porównywano z wynikami uzyskanymi na preparatach nieustabilizowanych. Wykazano, że brak ciągłości przedniej kolumny kręgosłupa nie wpływa na biomechaniczną jakość stabilizacji w zakresie stosowanych obciążeń. Wyniki analizy statystycznej jednoznacznie wskazują, że podatność kręgosłupa na obciążenia wpływa w sposób istotny na wartości przemieszczeń po stabilizacji przeznasadowej. Nie zaobserwowano istotnych statystycznie różnic w jakości stabilizacji pomiędzy poszczególnymi systemami.

EN

In the paper the results of influence of lumbar spine flexibility on quality of transpedicular stabilization are presented. In particular, measurements of displacements of the lumbar spine subjected to simultaneous compression and bending (eccentric compression) are shown. The displacements were measured at L3 level in nine lumbar specimens stabilized by means of Socon, Omega and Bial-Stab systems. The obtained results were compared with the results of measurements carried out on the specimens without stabilization. It was also shown that a lack of continuity of the anterior column did not influence on quality of the stabilizations in the range of the used loading. The statistical analysis showed that lumbar flexibility sufficiently influenced on the displacements of the fixed lumbar spine. No statistical differences were observed between of the systems used as regards their biomechanical performance.

19

Experimental and numerical analysis of urological stents

Kajzer W., Marciniak J.

Archives of Materials Science and Engineering

|

2007

|

Vol. 28, nr 5

297-300

EN

Purpose: In order to evaluate the characteristic changes of the stents' diameters in function of the elongation (during elastic expansion) the biomechanical tests were carried out. The numerical analysis of the selected forms of urological stents was performed. The numerical results were compared with the experimental ones. Design/methodology/approach: The urethral stent commonly used in clinical practice was analyzed. Two types of research were carried out: experimental-in order to determine the displacement characteristic of the stent, and numerical (by means of the finite element method)-in order to evaluate stresses and strains in the stent. Findings: The comperative analysis of the obtained experimantal and numerical results showed good correlation, that proves the proper selection of the modeling conditions, and boundary conditions adequate to the real object. Research limitations/implications: The limitations were connected with the necessity of simplifications applied to the numerical model of the urological stent, and also with the difficulties caused by the established boundary conditions. Practical implications: The self-expanding stents analyzed in the work are implants for which the change of the diameter causes the significant change of the length. Due to the fact, the very important issue during implantation of this type of stent is the appropriate positioning in the narrowed part of urethra. The worked out characteristics allows to determine the length of the implant for the given diameter. Originality/value: The work presents the dispacement characteristics of the stent obtained on the basis of the experimental and numerical tests. The correlation of the obtained results is also presented.

20

Biomechanical analysis of plates used in treatment of pectus excavatum

Krauze A., Marciniak J., Marchacz A.

Archives of Materials Science and Engineering

|

2007

|

Vol. 28, nr 5

301-304

EN

Purpose: The paper presents computer simulation results of displacement, strain and stresses in the plate used in treatment of the pectus excavatum. Design/methodology/approach: The numerical analysis was performed for selected models of the stabilizing plates made of the Cr-Ni-Mo stainless steel (AISI 316L) and Ti-6Al-4V ELI alloy. Findings: The displacement, strain and stress analyses showed the diverse results depending on the plates geometry and the properties of the applied metallic biomaterial. The numerical analysis shows that stresses in plates didn't exceed the yield point: for the stainless steel R p0,2 min=690 MPa and Ti-6Al-4V ELI - Rp 0,2min =895 MPa. Research limitations/implications: The limitations were connected both with the necessity of simplifications applied to the numerical model and with the established boundary conditions. Practical implications: The obtained results are the basis for the stabilizing plate optimization to ensure favorable conditions for the pectus excavatum treatment. Originality/value: The work presents the displacement-strain-stress characteristics obtained on the basis of the numerical analysis.