A PRACTICAL METHOD OF DETERMINING THICKNESS OF PLATES SUBJECTED TO INDIVIDUAL END FORCES

Bu çalışmada, dört ucundan ve orta noktasından kuvvetlere maruz bırakılan bir plak halinde kalınlık hesabına dair analitik bir formül geliştirilmektedir. Metod, federli plak halini de ihtiva edecek şekilde genişletilmektedir. Sonuçlar sadece pres gövdelerinin kalınlık tayini için değil, fakat aynı zamanda daha geniş bir kullanım alanı için de geçerlidir. In this study, an analytical formula is developed for a plate subjected to four forces at its corners and a force at its middle point. This formula is extended so as to include the case of corrugated plates. The results are valid not only for the thickness determination of presses, but also for a wider range of application

Regional intravenous anesthesia in knee arthroscopy

OBJECTIVE: The goal of the study was to investigate the regional intravenous anesthesia procedure in knee arthroscopy and to evaluate the effects of adding ketamine over the anesthesia block charactery and tourniquet pain. MATERIAL/METHOD: Forty American Society of Anesthesiologists (ASA) II patients who received knee arthroscopy were enrolled. After monitoring, a peripheral IV line was inserted.The venous blood in the lower extremity was evacuated with a bandage, and the proximal cuff of the double-cuff tourniquet was inflated. The patients were randomly split into two groups. While Group P received 80 ml 0.5% prilocaine, Group PK received 0.15 mg/kg ketamine (80 ml in total) via the dorsum of the foot. We recorded onset time of the sensory block, end time of the sensory block, presence of the motor block, the time when the patient verbally reported tourniquet pain and surgical pain, duration of tourniquet tolerance, fentanyl consumption during the operation, time to first analgesic requirement, methemoglobin values at 60 minutes, operative conditions, 24-hour analgesic consumption, discharge time, and hemodynamic parameters. RESULTS: The body mass index (BMI) of the patients who required general anesthesia was significantly higher than the BMI of other patients. The onset time of the sensory block was shorter for those in Group PK, but the time to first analgesic requirement was longer. CONCLUSION: Regional intravenous anesthesia using the doses and volumes commonly used in knee arthroscopy may be an inadequate block among patients with high BMI values. Moreover, the addition of ketamine to the local anesthetic solution may produce a partial solution by shortening the onset of sensory block and prolonging the time until the first analgesic is required

ON THE ELASTIC-PLASTIC TORSION OF A BAR MADE OF WORK HARDENING MATERIAL

In this study, we reconsider the problem of an elastic-plastic torsion of a bar made of work hardening material. Nonlinear partial differential equation derived is reduced to a well known Laplace equation by means of transformation functions and stresses τ xz, τ yz and the torque T are analytically found for elliptical and circular cross sections. It is further shown that the stresses and the twisting moment do not depend on the value of n in the stress-strain law

STRESS DISTRIBUTION IN A TOROIDAL RING SECTOR SUBJECTED TO BENDING AND TWISTING

In this study, stress analysis in a toroidal ring sector with an elliptical cross section composed of two confocal ellipses is considered. Göhner's method is used in the analysis. The results obtained for the case of pure torsion is superposed with those corresponding to pure bending in order to reach to the case of combined loading

Heat Distribution in a Rectangular Plate Heated by a Moving Heat Source

In this study, temperature distribution in a rectangular plate due to a moving heat source with a constant velocity is investigated and analytical expressions for the temperature are obtained. First, temperature distribution is obtained for a heat source moving with a constant speed at a constant direction. Second, how the present method can be modified for the process in different directions is expressed. Third, temperature distribution for the circular processing is formulated and solved. Heat source is defined by means of a Dirac Delta function. Results are exemplified for various values of the parameters. In order to provide the ease of use a GUI software in Matlab is also developed

Dikdörtgensel Plakalarda Hareketli Isı Kaynağının Oluşturduğu Sıcaklık Dağılımı

Bu çalışmada, sabit hızla hareket eden ısı kaynağı tarafından ısıtılan dikdörtgensel plaka üzerindeki sıcaklık dağılımı incelenmekte ve analitik sonuçlar verilmektedir. Birinci olarak kaynağın sabit doğrultuda ve sabit hızla hareket ettiği hal için sıcaklık sağılımı elde edilmektedir. Fraklı doğrultulardaki işleme sırasında oluşan sıcaklık dağılımının bulunması için mevcut yöntemin nasıl modifiye edilmesi gerektiği de açıklanmıştır. Son olarak dairesel ısı kaynağının oluşturduğu sıcaklık dağılımı elde edilmektedir. Her bir bölümde ısı kaynağı Dirac Delta distribüsyon fonksiyonu vasıtasıyla ifade edilmiştir. Sonuçlar parametrelerin çeşitli eğerleri için örneklendirilmiştir. Sanayide kullanımdaki kolaylığı sağlamak için tek ve çok doğrultulu işleme için Matlab GUI Toolbox yardımıyla bir de ara yüz yazılımı geliştirilmiştir

Vibration of a cracked cantilever beam under moving mass load / Įtrūkusios gembinės sijos virpesiai veikiant judančia masės apkrova

This study is devoted to the investigation of the vibration of a cracked cantilever beam under moving mass load. The present formulation contains inertial, centripetal and Coriolis forces that depend on mass and the velocity of the moving load. The existence of crack induces a local flexibility which is a function of the crack depth, thereby changing its vibration behavior and the eigen-values of the system. The response of the system is obtained in terms of Duhamel integral. The differential equation which involves complicated terms on the right side is solved via an iterative procedure. It has been shown that the centripetal and Coriolis forces make an effect to decrease the deformations on the beam since the deformed beam remains concave during the passage of the moving load. It has also been detected that the previous solutions for the case of moving constant force had several mistakes. The results are exemplified for various values of the variables. Santrauka Straipsnyje nagrinėjami įtrūkusios gembinės sijos, kurią veikia judančios masės apkrova, virpesiai. Šiuo atveju veikia inercinės, įcentrinės ir Koriolio jėgos, kurios priklauso nuo judančios apkrovos masės ir judėjimo greičio. Įtrūkis sukelia vietinį sijos lankstumą, kuris priklauso nuo įtrūkio gylio, tokiu būdu keičia virpesių pobūdį ir sistemos reikšmes. Sistemos atsakas nustatomas taikant Duhamelo integralą. Diferencialinė lygtis, kurios dešinėje pusėje yra sudėtingos sąlygos, sprendžiama taikant iteracijas. Nustatyta, kad įcentrinė ir Koriolio jėgos sumažina sijos deformacijas, nes deformuota sija išlieka išsigaubusi, kai per ją juda masės apkrova. Taip pat nustatyta, kad ankstesniuose sprendimuose judančios nekintamos masės apkrovų atvejais buvo keletas klaidų. Kaip pavyzdžiai pateikiami rezultatai esant skirtingoms kintamųjų reikšmėms. Reikšminiai žodžiai: sija, įcentrinė jėga, Koriolio jėga, įtrūkis, judanti masė, virpesia

STRESS DISTRIBUTION IN AN AXIALLY LOADED PLATE INCLUDING A HOLE WITH A CORRUGATED BOUNDARY

In this study, stress distribution in an axially loaded plate including a hole with corrugation is investigated. Perturbation technics is employed for the solution. Results reveal that stresses change in large amounts even for small variations in radius. Several graphics are given for the hoop stress that is especially important in tearing