Local Buckling of Thin-Walled Column of Square Cross-Section Made of In-Plane Coupled Laminate.

The non–symmetric, general laminate exhibits different types of coupling between the extension, shearing, bending and twisting. For practical reasons, the in–plane coupled laminate is a particularly interesting. In this case, the coupling between shearing andextension takes place. Details calculations were performed for a short columns of square cross-section made of in–plane coupled and fully uncoupled laminate under uniform compression. Finite element method (FEM) and analytical–numerical method (ANM) were performed. In FEM analyses, the eigenbuckling problem has been solved using the Lanczos method, whereas the nonlinear buckling analysis were performed using the Newton– Raphson method and the Ritz method. In ANM analyses, the Koiter’s asymptotic theory is applied. The relationship between forces/moments and deformations/curvature were described using classical lamination theory (CLT). The coupling between in–plane shearing and extension has a significant influence on the behavior of thin–walled structures under compression

AN INFLUENCE OF THE d311 EFFECT ON THE BEHAVIOR OF THE CANTILEVER BEAM-SHAPED PIEZOELECTRIC ACTIVATOR MADE OF TWO LAYERS OF PVDF WITH INVERSE POLARITY

In the present work an example of the numerical modeling of electro-mechanical coupling of the activator in the form of cantilever beam made of two layers PVDF subjected to an inverse polarity is described. Calculations were done for static deflections at the selected voltage levels and for modal analysis with an included and excluded piezoelectric effect. The effect of active material on the behavior of the beam was examined. In order to validate the model, results of the static calculation were compared with the strict analytical solution and the results presented by other authors

The assessment of overall survival (OS) after adjuvant chemotherapy for patients with malignant endometrial cancer in Poland

Objectives: In 2013 malignant endometrial cancers have amounted to 7.3% of all cancers diagnosed among women in the report by the Polish National Cancer Registry Raw prevalence rate amounted to 28.7, whereas standardised prevalence rate 15.6 per 100 000 population. Among the causes of death, these cancers amounted to 3% and were ranked ninth on the list of the most common causes of oncologic mortality of women. In the year 2013 a total of 1243 women died of malignant endometrial cancers. A stable increase of malignant endometrial cancer incidence has been observed for 2 decades. Despite that fact, the increase of the mortality incidence is at a much lower level, which demonstrates the much higher effectiveness of the treatment of such cancers. The recording rate of the malignant endometrial cancer mortality amounts to 95%, so the presented absolute numbers are reliable. Examining the clinical stages of malignant endometrial cancers, we can establish that approx. 85% of them are diagnosed at stage I or II according to the FIGO classification. Patients with advanced stages of cancer represent less than 15%. Material and methods: retrospective analysis of endometrial body cancer prevalence data for the entire population of Poland, assessment of malignant endometrial cancer prevalence in the years 2008–2015 and overall survival probability in the population of patients undergoing adjuvant chemotherapy. Results: The number of patients with a diagnosed malignant endometrial cancer within the studied period in Poland remains on a stable level (2008 — 30.6 thousand patients, 2015 — 40.2 thousand patients). Among all listed patients with the indica­tion of C54 each year approx. 20% enters hospital treatment. System therapy with chemotherapy drugs was used in approx. 1–2% of patients treated in hospitals. The average age of the patients was 64.9 years, and the median age 65 years. The num­ber of observations was 2085, including 1088 censored observations. The average survival for the sample under study was 30.67 month (SD = ± 0.6); median survival time was 23.93 month. The number of censored observations was 1088 (52.16%). Probable survival of 1 year is achieved by 67.57% of patients, 2 years by 49.73%, 3 years by 40.68%, above 5 years 30.77%. Conclusions: The incidence of endometrial cancer in Poland in the years 2008–2015 continues to grow at 5% upward trend (in Europe 3.4–5.9). In Poland in 2012, crude incidence rate for cancer of the uterus was 29.8 and did not differ significantly from the results in countries such as Finland, Slovakia, Sweden, Belgium and Bulgaria. The overall survival after adjuvant chemotherapy for patients with malignant endometrial cancer in Poland shows considerable differences depending on the region of the country

Rola markerów metabolizmu kostnego w kwalifikacji do leczenia osteoporozy. Wyniki programu POMOST

Introduction: Increased bone turnover markers (BTM) level is consider as independent risk factor of bone fracture. However, it was not used in 10-year probability of bone fracture method (FRAX) proposed by WHO, which helps in qualification of patients for pharmacological treatment of osteoporosis. The aim of the study was to evaluate the usefulness of BTM in qualification for pharmacological treatment of osteoporosis. Material and methods: The study was performed in 152 subjects (20 men and 132 women) referred to Krajowe Centrum Osteoporozy. One-hundred thirty two of them were qualified for pharmacological treatment and 20 for prophylaxis on the basis of qualitative method. The following BTM were examined in all patients: of bone formation - N-terminal propeptide of procolagen type I (PINP) and N-mid osteocalcin (OC) and of bone resorption - C-terminal cross-linked telopeptide of collagen type I (CTx). Results: The values over that considered as independent fracture risk (in women only, no data for men) were found in 39 women with PINP, 39 with OC and 41 with CTx. Part of women had decreased serum BTM (10 women 3 BTM and 35 with 1 at least). There were not significant differences in serum BTM depending on the presence of clinical fracture risk factors: osteoporotic fracture in past, osteoporotic hip fracture in parents, chronic treatment with glucocorticosteroids and qualification for pharmacological treatment on the basis of qualitative and FRAX method. There was no significant difference in the presence of fracture risk factors depending on increased or decreased serum BTM. Conclusions: Results of the study did not show the practical use of BTM in qualification for pharmacological treatment of osteoporosis.Wstęp: Za niezależny czynnik ryzyka złamania kości uważa się podwyższenie stężenia markerów metabolizmu kostnego (BTM, bone turnover markers). Nie uwzględniono tego jednak w metodzie oceny 10-letniego ryzyka złamania kości (FRAX) zaproponowanej przez Światową Organizację Zdrowia (WHO, World Health Organization), która ma ułatwiać decyzję o farmakologicznym leczeniu osteoporozy. Celem niniejszej pracy była ocena przydatności oznaczania stężenia markerów metabolizmu kostnego w kwalifikacji do leczenia farmakologicznego osteoporozy. Materiał i metody: Badania wykonano u 152 osób (20 mężczyzn i 132 kobiet), skierowanych do Krajowego Centrum Osteoporozy (KCO), spośród których 132 były zakwalifikowane do leczenia, a 20 do profilaktyki osteoporozy na podstawie metody jakościowej stosowanej w KCO. U wszystkich pacjentów oznaczono stężenie w surowicy markerów tworzenia kości: N-końcowy propeptyd prokolagenu typu I (PINP) i N-końcowy fragment osteokalcyny (OC) oraz resorpcji kości: C-końcowy usieciowany telopeptyd kolagenu typu I (CTx). Wyniki: Wartości powyżej progu uznanego za niezależny czynnik ryzyka złamania kości stwierdzono u 39 kobiet w przypadku PINP, 39 - OC i 41 - CTx (brak progowych wartości dla mężczyzn). Część chorych miała obniżone stężenie markerów w surowicy (10 kobiet 3 markery, 35 co najmniej 1). Nie stwierdzono istotnej różnicy stężeń markerów w zależności od obecności poszczególnych czynników ryzyka złamania kości (przebytego złamania osteoporotycznego kości, złamania biodra u rodziców i przewlekłego leczenia glikokortykoidami) oraz od kwalifikacji do leczenia osteoporozy na podstawie metody jakościowej i metody FRAX. Nie było istotnej różnicy w częstości występowania czynników ryzyka złamania kości w zależności od obniżenia czy podwyższenia stężeń (BTM). Wnioski: Nie wykazano praktycznego zastosowania oznaczania stężenia markerów metabolizmu kostnego przy podejmowaniu decyzji o konieczności leczenia farmakologicznego osteoporozy

Use of an active element for dynamic control of a thin-walled laminated beam with kinematic excitation

The paper describes the dynamics of a composite cantilever beam with an active element. The vibrations of the kinematically excited beam are controlled with the use of a Macro Fiber Composite actuator. A proportional control algorithm is considered. During the analysis, actuator is powered by a time-varying voltage signal that is changed proportionally to the beam deflection. The MFC element control system with the implemented algorithm allowed for changing the stiffness of the tested structure. This is confirmed by the numerical and experimental results. Resonance curves for the beam with and without control are determined. The results show a very good agreement in qualitative terms

Catastrophic Influence of Global Distortional Modes on the Post-Buckling Behavior of Opened Columns

The multimodal buckling of thin-walled isotropic columns with open cross-sections under uniform compression is discussed. Column lengths were selected to enable strong interactions between selected eigenmodes. In the case of short columns or very long ones subjected to compression, single-mode buckling can be observed only and the effect under discussion does not occur. In the present study, the influence of higher global modes on the load-carrying capacity and behavior in the post-buckling state of thin-walled structures with open cross-sections is analyzed in detail. In the literature known to the authors, higher global modes are always neglected practically in the analysis due to their very high values of bifurcation loads. However, the phenomenon of an unexpected loss in the load-carrying capacity of opened columns can be observed in the experimental investigations. It might be explained using multimode buckling when the higher global distortional-flexural buckling modes are taken into account. In the conducted numerical simulations, a significant influence of higher global distortional-flexural buckling modes on the post-buckling equilibrium path of uniformly compressed columns with C- and TH-shaped (the so-called “top-hat”) cross-sections was observed. The columns of two lengths, for which strong interactions between selected eigenmodes were seen, were subject to consideration. Two numerical methods were applied, namely, the semi-analytical method (SAM) using Koiter’s perturbation approach and the finite element method (FEM), to solve the problem. The SAM results showed that the third mode had a considerable impact on the load-carrying capacity, whereas the FEM results confirmed a catastrophic effect of the modes on the behavior of the structures under analysis, which led to a lack of convergence of numerical calculations despite an application of the Riks algorithm. All elastic-plastic effects were neglected

Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range

The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory

Assessment of piezoelectric layers and boundary conditions influence on the behaviour of hybrid composite plates with different layups

In the present paper, six-layer hybrid composite panels, made of four-layered laminate and two facings of piezoelectric material were studied. Different configurations of laminate layers and different boundary conditions were considered. The Numerical simulations using Finite Element Method were performed with the commercial system Abaqus, which allowed for modelling the phenomena of electromechanical coupling, both in static and dynamic cases. Firstly, static deflection of the plates induced by the applied voltage on the external facings was determined with numerical methods (FEM). In addition, the deflections at different voltages were compared. The results of static calculations were validated with those published by other authors. The performed simulations have confirmed the adequacy of the FEM model for the simulation at electromechanical coupling. In the second stage, numerical analysis of the system with piezoelectric effect (open system) and without the piezoelectric effect (closed system) was performed. The presented FEM models are expected to contribute to analyses of other hybrid structural elements exhibiting electromechanical coupling.[b]Keywords[/b]: FEM, electro-mechanical coupling, piezoelectric effect, fibrous laminate, natural frequencies, hybrid beam, PZT, actuator