Finite element analysis (FEA) modeling on adhesive joint for composite fuselage model

In this paper, a finite element modeling via ABAQUS/Explicit simulation on a novel fabrication miniature composite fuselage structure is presented. The fuselage structure is modeled as a continuum composite layup that consisted of a woven C-glass fiber/epoxy 200 g/m 2 composite laminated [90 8] with the orthotropic elastic material properties and adhesively bonded butt joint. The adhesively bonded joint progression is modeled using cohesive elements technology. For the purpose of FEA modeling, an experiment of double cantilever beam (DCB) according to ASTM standard D5528 is performed to determine the adhesive mode-I critical toughness. The mode-I interlaminar fracture toughness data (G I) are calculated and compared by four different methods according to the ASTM standard: BT, beam theory, MBT, modified beam theory, CC, compliance calibration method and MCC, modified compliance calibration method. The results indicate that ABAQUS/Explicit is able to reproduce satisfactory adhesive joint behavior using cohesive elements and collapse modes under crushing process

Assessment of oral acetazolamide on postoperative pain after laparoscopic cholecystectomy

Background and aim: Carbon dioxide (Co2) is used during laparoscopy for producing pneumoperttoneum. Combination of this gas with irrigation fluid in the abdomen produces carbonic acid which creates two kinds of abdominal and referred pain to right shoulder. In the present research we have studied the effect of oral acetazolamide in reducing postoperative pain after laparoscopic cholecystectomy. Methods: This clinical trial was performed in 88 patients with cholelithiasis without any complication that were candidate for laparoscopic cholecystectomy. The patients devided randomly and equally in two groups. The experimental group received Acetazolamide (250mg orally 24 hours before surgery every 8 hours) and control group received placebo. Abdominal and shoulder pain measured using Mc Gill pain score by a person who was blind for both groups. Pain measurement was performed in four different times before and after the surgery discharge from recovery and 24 hours after surgery. Data were analyzed by using SPSS software. Results: We observed that mean pain scores was significantly higher in acetazolamide group compared to the placebo group 24 hours after the operation (P0.05). Conclusion: Although acetazolamide can reduce abdominal pain referred to right shoulder by reducing acidity in peritoneal irrigation fluid but this drug can increase abdominal pain in the site of surgery with damaged tissues by producing tissue acidosis (as a side effect of drug)

The relationship between postural abnormalities and quality of life and mental health of girl students of Arak Farhangian University

زمینه و هدف: وجود ناهنجاری های وضعیتی، تأثیر نامطلوبی بر درک و تصور بدنی به خصوص در افراد جوان دارد. ناهنجاری ها اگر به موقع شناسایی و درمان نشوند ممکن است آثار نامطلوبی بر عملکرد فیزیولوژیک بدن داشته باشند. هدف این پژوهش، بررسی ناهنجاری های عضلانی اسکلتی ستون فقرات دانشجویان دختر پردیس دانشگاه فرهنگیان اراک و ارتباط آن با سلامت روان و کیفیت زندگی می باشد. روش بررسی: پژوهش حاضر از نوع توصیفی مقطعی و همبستگی محسوب می شود. در این مطالعه، نمونه ای 120 نفری از دانشجویان به روش تصادفی خوشه ای، انتخاب گردید. به منظور گردآوری داده های مربوط به ناهنجاری های عضلانی اسکلتی، از صفحه شطرنجی و آزمون سازمانی نیویورک و خط مرجع شاقولی و خط کش منعطف و جهت جمع آوری اطلاعات مربوط به کیفیت زندگی و سلامت روان از دو پرسشنامه ی معتبر GHQ و پرسشنامه سلامت روان گلد برگ استفاده شد. یافته ها: نتایج حاصل از تحلیل داده ها نشان داد که حدود 91 دانشجو معلمان دارای انواع مختلفی از ناهنجاری های عضلانی اسکلتی بودند و تنها بین کیفیت زندگی دانشجویان با ناهنجاری های عضلانی اسکلتی رابطه معکوس و معنی داری وجود دارد (05/0>P). نتیجه گیری: ناهنجاری های عضلانی اسکلتی، نه تنها در سلامت جسمی و کارکرد اندام ها موثر است، بلکه بر فاکتورهای روان شناسی نیز تأثیرگذار خواهد بود. بنابراین می توان نتیجه گرفت که شناسایی به موقع آن ها تأثیر به سزایی در سلامت جسمی و روحی افراد جامعه خواهد داشت

Natural frequency of F.G. rectangular plate by shear deformation theory

Natural frequency of functionally graded (F.G.) rectangular plate is carried out by using second-order shear deformation theory (SSDT). The material properties of functionally graded rectangular plates, except the Poisson's ratio, are assumed to vary continuously through the thickness of the plate in accordance with the exponential law distribution. The equations of motion are obtained by energy method. Numerical results for functionally graded plates are given in dimensionless graphical forms and the effects of material properties on natural frequency are determined

Optimal sintering procedure to fabrication of functionally graded Hydroxyapatite-Titanium

Functionally graded metal-ceramic composite was fabricated by pressure-less sintering. The pure metallic component (Ti) and the pure ceramic component (HA) were located at the ends of a cylindrical specimen. Titanium and-Hydroxyapatite were utilized as a metallic and ceramic layer. The target sample thickness was 6 mm with radius cylindrical 20 mm. The sample was made from the cylindrical type of carbon die consisting of 5 layers. The composition of layers were 100%Titanium; 75 % Titanium +25% HA; 50% Titanium +50% HA; 25% Titanium+75% HA, and 100% Hydroxyapatite. The optimum thermal load mapping was obtained experimentally. The properties of all FGM products were characterized by shrinkage, optical-microscope, energy dispersive spectrometry (EDX) scanning electron microscope (SEM). The grade of the FGM material was proven by comparing amount of shrinkage after sintering. Result from optical micrograph, SEM and EDX indicated that the HA-Ti FGM could be produced successfully by using the optimal sintering procedure that was highlighted in this paper

Free vibration analysis of functionally graded quadrangle plates using second order shear deformation theory

A general approach for free vibration of functionally graded materials (FGMs) plates based on second-order shear deformation theory (SSDT) is presented. Material properties are assumed to be graded in the thickness direction by power law distribution in term of the volume fractions of the constituents. The equilibrium equations are derived by energy method and then solved analytically by applying Navier's method for a plate with simply supported boundary conditions. It is found that the fundamental frequencies versus side-to-side ratio for FG quadrangular plates are between full-ceramic plate and full-metal plate. It is shown that for the grading index smaller than two (p<2) the decreasing slope of the frequency is greater than that in other parts for all values of side-to-thickness ratio in square FG plate. Natural frequencies for different mode shape are compared and verified with the known results in the literature. It is seen that the results of the second-order theory are very close to the third-order reported in the literature

Thermal free vibration analysis of temperature-dependent functionally graded plates using second order shear deformation

This research has been conducted to approach second-order shear deformation theory (SSDT) to analysis vibration characteristics of Functionally Graded Plates (FGP’s). Material properties in FGP's were assumed to be temperature dependent and graded along the thickness using a simple power law distribution in term of the volume fractions of the constituents. FGP was subjected to a linear and nonlinear temperature rise. The energy method was chosen to derive the equilibrium equations. The solution was based on the Fourier series that satisfy the simply supported boundary condition (Navier's method). Numerical results indicated the effect of material composition, plate geometry, and temperature fields on the vibration characteristics and mode shapes. The results revealed that, the temperature field and volume fraction distribution had significant effect on the vibration of FGPs. It was observed the second order theory was very close to the other shear deformation theorem as reported in the literature

Second order shear deformation theory for response analysis on temperature-dependent functionally graded plates due to vibration and mechanical loading

The Second-order Shear Deformation Theory (SSDT) is applied to evaluate the displacement and stress fields included in a functionally graded plate (FGP) by thermo-mechanical loadings. Uniformity, linearity, nonlinearity, heat-flux, and sinusoidal thermal conditions are imposed at the upper and lower surfaces of the FGps. The SSDT is also employed to analyze the free vibration of temperature dependent and independent FGP's. Equilibrium equations and equations of motion of FG square and rectangular plates are derived by employing second order shear deformation theory (SSDT). Navier's method is applied to find the analytical results for the derived equations using an energy method for the case of simply supported boundary conditions. The power law material properties and linear steady-state thermal loads are assumed to be graded between full ceramic at the upper and full metal at the lower surface. In the numerical study, different types of FGPs such as ZrO2/Ti-'6Al-_4V and Si3N4/SUS3O4 are considered. A comparison is made of the non-dimensional results for the temperature-dependent and temperature- independent FGPs and validated using the results published in the literature. By comparing the results with some numerical results, a quantitative agreement is exhibited. This research sWdy used numerical results to quantify the effects of material composition, plate geometry, and temperature fields on vibration characteristics and mode shapes. The effects of the material grading index of a plate on stresses and displacements were investigated to reveal that, the longitudinal stresses in the FGP lie between full-metal and full-ceramic plates. It was found that, the neutral axes for FGP move to the upper surface not to the mid-surface as predicted in homogeneous plates. The SSDT has computed results for in-plane stresses, free vibration and displacement fields, which are acceptable and exhibit very close qualitative behavior and quantitative agreement to other shear deformation theories in existing literature, thus demonstrating its robustness

Free vibration analysis of solar functionally graded plates with temperature-dependent material properties using second order shear deformation theory

Second-order shear deformation theory (SSDT) is employed to analyze vibration of temperature-dependent solar functionally graded plates (SFGP’s). Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Two different types of SFGP’s such as ZrO2/Ti-6Al-4V and Si3N4/SUS304 are considered. Uniform, linear, nonlinear, heat-flux and sinusoidal thermal conditions are imposed at the upper and lower surface for simply supported SFGPs. The energy method is applied to derive equilibrium equations, and solution is based on Fourier series that satisfy the boundary conditions (Navier’s method). Non-dimensional results are compared for temperature-dependent and temperature-independent SFGP’s and validated with known results in the literature. Numerical results indicate the effect of material composition, plate geometry, and temperature fields on the vibration characteristics and mode shapes. The results obtained using the SSDT are very close to results from other shear deformation theories