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© 2023 Wiley-VCH GmbH.This study reports the results of a preliminary study of manufacturing aluminum–potassium feldspar metal matrix composites including its castability and mechanical properties. The material was composed considering 0.25 %, 0.5 %, and 0.75 % additive ratios to examine the impact of the amount of potassium feldspar on the material and mechanical properties of the manufactured aluminum metal matrix composite material. Aluminum alloy (A356) was utilized as the matrix of the composition. The composite material was manufactured by the stir casting technique. The modulus of elasticity, yield strength, tensile strength, elongation, density, and quality index of the material parameters was taken into account to determine the materials′ practicality. The preliminary results indicated that potassium feldspar is a promising mineral to be utilized as an additive for aluminum metal matrix composites since it has a positive impact on mechanical properties. By optimizing the casting parameters, the positive aspects of the potassium feldspar may make the material more practical to be utilized in vast engineering applications.

Background. The aim of the present study was to measure the effects of raloxifene on bone metabolism and strength in orchiectomized male rats.

Objectives: Although limited carpal fusions used in the treatment of Kienböck’s disease are thought to act by decreasing the loads on the lunate, biomechanical studies show that capitohamate fusion acts oppositely to what is expected. This experimental study was designed to resolve this paradox,Methods: In a biomechanical cadaveric study, load transmissions at the radioulnacarpal joint were investigated under 140 and 210 newtons of load with three wrist postures, namely, neutral, ulnar and radial deviations, in five intact wrists and after scaphotrapeziotrapezoid, capitohamate, and scaphocapitate fusions.Results: Under 140 newtons of load, the loads imposed to the lunate decreased following scaphotrapeziotrapezoid and scaphocapitate fusions, but increased after capitohamate fusion. However, when the load was increased to 210 newtons, there were no differences between intact wrists and limited carpal fusions in respect to the loads exerted on the lunate. In all the situations, the lunate was subjected to a significantly greater load in ulnar deviation.Conclusion: These results suggest that limited carpal fusions do not alter load transmission characteristics of the wrist joint under 210 newtons of load. The etiology of the Kienböck’s disease seems to be related to an overload in ulnar deviation and the beneficial effect of limited carpal fusions seems to be associated with restricted ulnar deviation of the wrist rather than load transmission characteristics., Amaç: Kienböck hastalığı tedavisinde kullanılan sınırlı karpal füzyonların lunatum üzerindeki yükü azaltarak etki ettikleri düşünülmesine karşın, biyomekanik çalışmalar kapitohamat füzyonunda lunatum yükünün arttığını göstermektedir. Bu deneysel çalışma bu çelişkiyi aydınlatmak amacıyla planlandı.Çalışma planı: Bu biyomekanik çalışmada, beş taze kadavra el bileğinde, 140 ve 210 newtonluk (N) yüklenmeler altında sağlam eklemlerle ve sınırlı karpal füzyonlarda (skafotrapeziotrapezoid, skafokapitat, kapitohamat) nötral, radial ve ulnar deviyasyonda yük dağılımları incelendi.Sonuçlar: Yüklenme 140 N iken, skafotrapeziotrapezoid ve skafokapitat füzyon sonrasında her pozisyonda lunatuma gelen yüklerde azalma, kapitohamat füzyon sonrasında artış görüldü. Yüklenme 210 N’ye çıkarıldığında, yüklerin dağılımı sağlam el bileğinde elde edilen değerlerden farklı değildi. Her iki yüklenme altında da, ulnar deviyasyonda iken lunatumun anlamlı derecede daha fazla yük altında kaldığı görüldü.Çıkarımlar: Bu sonuçlar, 210 N’lik yüklenme altında, sınırlı karpal füzyonların el bileğindeki yük dağılımını değiştirmediğini göstermektedir. Kienböck hastalığı etyolojisinde ulnar deviyasyon yüklenmesi olduğu ve sınırlı karpal füzyonların el bileği yüklenme özelliklerini değiştirerek değil, ulnar deviyasyonu kısıtlayarak etki ettiği düşünülebilir.

Introduction: The aim of this study is to evaluate the biomechanical properties of the interbody device which is used in thoracic trauma, infection and tumor surgery in valf model. The comparison in between anterior interbody application, anterior, posterior and anterior posterior instrumentation combinations is also stated. The statical applications of interbody device in conditions with anterior interbody applications, anterior, posterior and anterior+posterior instrumentation combinations are done through the gain of stiffness and displacement. In this biomechanical study, instrument stiffness and displacement values are measured and evaluated under axial loading.

Objectives: We evaluated the effects of radial shortening osteotomy on the radiolunate joint load distribution.

Bu çalışmada; 17Mn4 (P295GH) kazan çeliği ve AISI304 paslanmaz çelik, ER309L östenitik kaynak dolgu malzemesi kullanılarak kaynaklanmıştır. Kaynak yöntemi olarak gaz tungsten ark kaynağı seçilmiştir (TIG (GTAW)). Kaynaklı levhalardan çıkarılan numuneler üzerinde sertlik taraması ve çekme deneyi yapılmıştır. Kaynak bölgesinde kırılma tokluğu davranışını incelemek için tek taraftan çentikli eğme deney numuneleri ile J-integrali değerleri ASTM E 1737-96 ya göre hesaplanmıştır. Kaynaklı numune üzerinde değişik bölgelere strain-gage yapıştırılarak tek eksenli çekme yapılmış ve plastik deformasyonun başlamasının engellendiği bölgeler tespit edilmiştir.Çalışmanın sayısal kısmında, sonlu elemanlar analizleri farklı bölgelerin ön çatlaklar içeren 2 boyutlu modeller oluşturularak gerçekleşmiştir. Bu modellerde, gerilme şekil değiştirme analizlerinden sonra çatlak civarındaki üç eksenli gerilme ve plastik deformasyon karakteristikleri her bir çatlak bölgesi için belirlenmiştir. J ? integrali değerleri bütün çatlak bölgeleri için sonlu elemanlar metodu ile hesaplanmıştır. Plastik deformasyon ilerlemesinin ısı tesiri altında kalmış bölgede ve difüzyon çizgisinde engellenmesi çatlak ucunda fazladan bir üç eksenli gerime artışına neden olmaktadır. In this study, 17Mn4 (P295GH) pressure vessels steel and AISI304 stainless steel are welded with ER309L austenitic consumable. GTAW, Gas Tungsten Ark Welding was selected as a method of welding. Hardness and tensile tests were done on welded plates. J - Integral fracture toughness values are calculated according to the ASTM E1737-96 with Single-Edge bend specimen, to investigate fracture toughness characteristics on weld region. In order to detect the regions where plastic deformation did not take place, uni-axial tensile test was performed on welded tensile specimen after attaching strain gages.In numerical part of the study, finite element (FE) analyses were conducted by fixing 2-D models precracked on different locations. In these models, stress triaxiality and plastic deformation characteristics around crack tip were determined for each crack locations after stress ? strain analyses. J ? Integral values were calculated for all crack locations with finite element method. The limitation on the extension of plastic deformation at HAZ and diffusion line causes extra increase in stress triaxiality at crack tip. 66

OBJECTIVES: Although limited carpal fusions used in the treatment of Kienböck's disease are thought to act by decreasing the loads on the lunate, biomechanical studies show that capitohamate fusion acts oppositely to what is expected. This experimental study was designed to resolve this paradox. METHODS: In a biomechanical cadaveric study, load transmissions at the radioulnacarpal joint were investigated under 140 and 210 newtons of load with three wrist postures, namely, neutral, ulnar and radial deviations, in five intact wrists and after scaphotrapeziotrapezoid, capitohamate, and scaphocapitate fusions. RESULTS: Under 140 newtons of load, the loads imposed to the lunate decreased following scaphotrapeziotrapezoid and scaphocapitate fusions, but increased after capitohamate fusion. However, when the load was increased to 210 newtons, there were no differences between intact wrists and limited carpal fusions in respect to the loads exerted on the lunate. In all the situations, the lunate was subjected to a significantly greater load in ulnar deviation. CONCLUSION: These results suggest that limited carpal fusions do not alter load transmission characteristics of the wrist joint under 210 newtons of load. The etiology of the Kienböck's disease seems to be related to an overload in ulnar deviation and the beneficial effect of limited carpal fusions seems to be associated with restricted ulnar deviation of the wrist rather than load transmission characteristics.

m ÖZET Bu çalışmada, nikel elektrodun dolgu malzemesi olarak kullanıldığı ön ısıtmasız soğuk ark kaynağı metoduyla küresel grafitli dökme demirin birleştirme işlemi yapılmıştır. Kaynak işleminden sonra, kaynaklı numunelerde farklı mekanik özelliklere sahip değişik bölgeler görülmüştür. Bu bölgelerin (kaynak metali, ana metal ve ısı tesiri altındaki bölge (ITAB)) mekanik ve metalografik özellikleri kaynaklı numunenin kırılma davranışını etkiler. Kaynaklı numunelere ait J-integral değerleri, mekanik ve metalografik özellikler belirlenmiştir. Bu çalışmanın temel amacı, kaynak metali ve ana metalin mekanik özellikleri ve kırılma davranışları arasındaki farkın belirlenmesiyle mukavemet uyumsuzluğunun etkisinin incelenmesidir. II ABSTRACT In this study, the process of joining of the nodular cast iron has been done with cold arc welding method by using the nickel electrode as filling metal without preheating. After the welding process, welded specimens have shown various regions with different mechanical properties. The mechanical and the metallographical properties of these regions (weld metal, base metal and heat-effected zone (HAZ)) affect the fracture behavior of welded specimens. The values of J-Integral, mechanical and metallographical properties of the welded specimens have been identified. The fundamental aim of this study is to examine the effect of yield strength mismatch by determining the difference of mechanical properties and fracture behaviors between the weld metal and the base metal. 52