Challenge Journal Publications (TULPAR Academic Publishing)
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Methods for multi-segment continuous cable analysis
Full text linkCables are invaluable members for some applications of engineering. The specialty is due to its behavior under transverse loads. Having almost no rigidity in transverse direction makes cables different from other structural elements. In most applications, cables are assumed to be two force members. However, not only its weight but also its application with roller supports makes them different structural elements. Generally, cables are assembled as single-segmented cables (SSC) where they are fixed at their ends. However, in most of the SSC applications, cables have intermediate supports which can be rollers or sliders. These type of cable applications are called as multi-segment continuous cables (MSCC). In MSCC systems, the cable fixed at its ends and supported by a number of intermediate rollers. Total length of cable is constant, and the intermediate supports are assumed to be frictionless and stationary. In this problem, the critical issue is to find the distribution of the cable length among the segments in the final equilibrium state, so reactions at all supports can be found. Two methods are proposed for the segment length adjustment based on the stress continuity among the cable. These methods are named as direct stiffness method and tension distribution method (relaxation method). Results calculated from the proposed methods are verified by both the reference benchmark problems and commercial finite element program
Anesthesia in patients with electrical burn: A retrospective study
No full textAim: We aimed to share our anesthesia experiences with patients hospitalized for electrical burns and underwent surgical intervention under anesthesia in the burn clinic of our hospital.Method: Data gained from our hospital's patient files and medical information system were retrospectively evaluated. The study included patients diagnosed with electrical burns hospitalized in our burn clinic in 2018-2022.Results: The study involved files of a total of 694 patients. Fifty (7.2%) patients were treated for electrical burns. The required data from 3 of the patients could not be accessed, therefore the study was completed including 47 patients. We found that 22 patients did not need surgical treatment. Twenty-five were given anesthesia for different surgical procedures: 20 of those received general anesthesia, while five underwent neuraxiel anesthesia/regional anesthesia. There were no anesthesia-related complications in any patients in the perioperative period.Conclusions: Anesthesia applications should be carefully planned against possible complications in patients with electrical burns
Spinal anesthesia in a patient with Darier’s disease: A case report
Full text linkDarier’s Disease (Darier-White Disease, keratosis follicularis) is a rare genodermatosis characterized by keratinisation defects that affects the skin, nails and mucosal membranes; it is autosomal and dominantly inherited. To the best of our knowledge, only one case has been reported regarding spinal anesthesia management in a patient suffering from Darier’s disease—this was during Cesarean section. Here, we describe a case of spinal anesthesia with standard skin preparation for inguinal hernia surgery in a Darier’s patient. Spinal anesthesia is a safe anesthesia choice when administered in lesion-free areas
Numerical investigation of the effective mechanical properties of Octet Truss lattice structures with different strut geometry
Full text linkLattice structures have an important role in lightweight structure applications as they can supply their mechanical performance with less material. Porous structures designed with inspiration from nature, has been used in many industries such as aerospace, automotive, defense industry and biomedical field. In order to continue these advances, studies on various design configurations of porous structure geometries are carried out. This study aimed to increase the usage potential of Octet Truss lattice structures in various sectors. A numerical model is created for 3 variable parameters: strut geometry, porosity, and material type. The effective elastic modulus values are determined based on the principles of Hooke's law for each model. Based on the obtained effective elastic modulus values, it has been concluded that differences in strut geometries, porosities, and material types contribute to 1.27%, 68.85%, and 29.86% of the observed effects, respectively. In order to establish a correlation between these factors, the data is transmitted to the MATLAB software, where equations are generated using the curve fitting approach. A total of nine equations have been generated and the R-square for these equations above 0.99. According to the two desired constant values, the effective elastic modulus can be calculated using these equations without any restrictions
Database studies and hemogram derivatives in perioperative medicine research: Does it mean taking shortcuts in the scientific journey?
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Axial compression behaviour of concrete-filled auxetic tubular short columns
Full text linkConcrete-filled steel columns (CFSCs) are of great interest in the literature as they are capable of carrying higher loads by combining the exceptional qualities of steel and concrete. With auxetic materials being introduced to civil engineering applications, the influence of these materials on CFSCs remains a matter of curiosity. The current study implements a nonlinear finite element analysis to evaluate the performance of circular CFSCs with six auxetic tubes under axial compression and the proposed numerical model was validated using published experimental data. The effect of the auxetic steel tube’s porosity and Poisson’s ratio on CFSCs was examined parametrically in terms of ultimate strength using the confined concrete model. Moreover, the stress distributions of the concrete and the auxetic steel tubes were also thoroughly examined. Based on the findings of the analysis, the ultimate load of CFSCs, utilising auxetic tubes with the same density and porosity but different Poisson’s ratio, increased proportionally with the increase of auxetic behaviour. When it comes to auxetic tubes with different densities and porosities, the influence of the Poisson’s ratio of the tubes diminished and the stiffness of tubes became more dominant over the mechanical characteristics of columns as the density of the auxetic steel tubes increased or decreased. The stiffness of the auxetic tubes reduced as porosity increased, as did the ultimate load of the columns. Additionally, the ultimate loads of the auxetic steel tube columns are found to be lower than those of bare steel tube columns filled with concrete due to perforations
Performance of light weight ferrocement composite walls
Full text linkThe aim of this research is to examine the performance of reinforced lightweight ferrocement walls under vertical and horizontal loading. The walls were made up of two thin layers of ferrocement reinforced with one, two, three, or four layers of welded wire mesh or expanded steel mesh. The panels’ core was constructed of lightweight extruded foam. An experimental program of thirteen lightweight walls with total dimensions of 100x650x1250 mm was casted to achieve this goal and tested until failure. ABAQUS finite-element package was conducted. The parameters in this study were the kind of reinforcement; welded and expanded wire meshes, the steel bars, and. the number of layers of steel mesh. Ultimate load, mode of failure, initial cracking load, service load, energy absorption, and ductility ratio were calculated and observation to evaluate the findings. The findings displayed that the performance of the ferrocement walls reinforced with expanded wire meshes is better than that of the walls reinforced with welded wire meshes. The energy absorbed increased by 40 % for specimens reinforced with expanded wire meshes is more than that of the walls reinforced with welded wire a good agreement was observed among the theoretical and experimental observations. This paper highlights uses of employing light weight ferrocement units in building of economic housing, which is particularly valuable for both developed and developing nations, with significant frugal benefits
Investigation of optimum tuned mass damper parameter according to stroke capacity
Full text linkDuring major earthquakes, civil structures may collapse due to vibration that has a frequency close to the frequency content of the structure. Because of this, control systems have also been proposed for building structures. These systems can be active ones that are controlled by electronic devices or passive ones that are tuned mechanical systems. Passive tuned mass dampers (TMDs) include mass, stiffness element and damping element and these are tuned around the frequency of the structure. For optimum tuning and the complex nature of the mathematics under random vibrations, metaheuristic algorithms are needed to be used. In the presented study, TMDs are optimized via Jaya algorithm. The control system was optimized for displacement minimization of the structure. Additionally, the stroke amount of the system was limited. The stroke capacity factor was investigated for wide limits between 0.5 and 4 for normalized stroke according to the maximum displacement of the structure. The investigation was done for a single degree of freedom structure for a general conclusion. It is observed that the stroke limit did not affect performance and optimum parameters after 2.75. The small values of the stroke limit have significantly different optimum period. <w:LsdException Locke
Three-dimensional static analysis of reinforced concrete cantilever beam using MATLAB Partial Differential Equation Toolbox
Full text linkNowadays, three-dimensional (3D) solid model of the structures can be prepared by using computer aided design programs. There are many numerical methods for static, dynamic and temperature analysis of structural systems. The most preferred among these methods is the finite element method (FEM). In this method, the structural model with different geometry and boundary conditions should be solved by utilizing partial differential equations. Due to the long solution time while performing, finite element programs require computers with very good features. Therefore, analyses with desired features can be performed by using open source programs to shorten the duration of analysis. In this study, specifically, the static analysis of the selected reinforced concrete (RC) cantilever beam was carried out by using the open source MATLAB partial differential toolbox based on the FEM. Since the program used is open source, different concrete classes and finite element models were selected for the cited cantilever beam and static analyses were performed. As a result of the MATLAB partial differential toolbox analyses, the displacement, stress and deformation of the cantilever beam were obtained in 3D and compared with the ones obtained from ANSYS computer program
Natural frequencies of porous orthotropic two-layered plates within the shear deformation theory
Full text linkThis paper analyzes the natural frequencies of porous orthotropic laminated composite plates with two different porosity models based on the higher-order shear deformation theory. The fundamental relations of natural frequency analysis are derived by using the virtual work principle and hyperbolical shear deformation theory. The obtained partial differential equations system is reduced to an ordinary differential equations system via approximation functions suitable for simply supported boundary conditions and the Galerkin method. After some mathematical operations, the natural frequency equation of porous orthotropic laminated composite plates is obtained in the framework of hyperbolical shear deformation theory. The natural frequency equation based on the classical laminated plate theory can be determined by ignoring the shear strains in the theoretical formulations. After two validation studies by using appropriate results in the literature, parametric analyses are performed to show the sensitivity of natural frequencies to shear deformation, porosity model, orthotropy, layer sequence, and geometric properties