The Flexural Fatigue Behavior of Honeycomb Sandwich Composites Following Low Velocity Impacts

This study experimentally investigated the flexural fatigue behaviors of honeycomb sandwich composites subjected to low velocity impact damage by considering the type and thickness of the face sheet material, the cell size and the core height parameters. Carbon-fiber reinforced composite and the aluminum alloy was used as the face sheet material. First, the static strength of undamaged and damaged specimens was determined by three-point bending loads. Secondly, the fatigue behaviors of the damaged and undamaged specimens were determined. Low velocity impact damage decreased the flexural strength and fatigue lives but increased the damping ratio for all specimens. Maximum damping ratio values were observed on specimens with a aluminum face sheet

Yapıştırıcı ve Perçinle Birleştirilmiş Çift Bindirme Bağlantılarında ilerlemeli Hasar Analizi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2011Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2011Bu çalışmada, yapıştırıcı ve perçin kullanılarak birleştirilmiş çift bindirme bağlantılarında ilerlemeli hasar analizi gerçekleştirilmiştir. Bağlantılarda ana malzeme olarak örgü tipi cam fiber takviyeli kompozit malzeme kullanılmıştır. Analizler APDL (Parametric Design Language) kodlan kullanılarak yazılan bir program yardımı ile Ah/SYS 12.1 sonlu elamanlar paket programı kullanılarak gerçekleştirilmiştir. 30, 45 ve 60 mm olmak üzere üç farklı bindirme mesafesi için yapıştırıcı ve perçin kullanılarak birleştirilmiş bağlantıların ilerlemeli hasar analizi sonucunda elde edilen hasar yükleri ve hasar tipleri Maksimum Kayma Gerilmesi Teorisi ve Hashin Kriterine göre tespit edilmiştir. Elde edilen sonuçlar birleştirme tipine ve bindirme mesafesine göre karşılaştırılarak sunulmuştur

EFFECT OF RIVETING ON THE JOINT STRENGTH OF ADHESIVELY BONDED DOUBLE LAP JOINTS

The scope of this study, is to determine the effectiveness of using rivets in the adhesive joints in order to combine plastic based composite materials which are often used in today's engineering structures, to the joint strength. For this purpose, double lap joints are prepared in 3 different types of configuration included adhesive, pinned and both adhesive and pinned and also prepared in 3 different overlap lengths as 30, 45 and 60 mm. Stress-strain diagrams were derived by exposing the joints obtained, to the axial tensile test and then the most appropriate joint type was determined by comparing each of the results obtained. The evaluation of the results pointed out that the hybrid joints where adhesive and rivet are used together, can carry much more load than the joints where only adhesive was used or the joints which are combined with rivet in terms of joint strength

Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants

The aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland), which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in FIII (300 N). The maximum stress values occurred in FIII (300 N) when the Nobel Replace implant is used, whereas the lowest ones, in the case of FI (150 N) loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact

Türkiye’ de Pediatrik Nötropenik Hasta İzlemi

Objective: Infection is a common complication in children with malignancies. There is no consistent guidance for environmental infection control and isolation precautions for neutropenic patients (NP). There are differences between centers. the aim of this questionnaire study was to determine these differences in Turkey. Material and Methods: A multicenter-descriptive questionnaire was conducted on 36 centers from different geografical locations of Turkey. Bone marrow transplantation units were excluded. Each center was contacted at least three-times. Questionnaire was answered by two different doctors from each center. Results: Thirty-six centers including 20 (55.5%) University Hospitals, 12 (%33.3) Research Hospitals, three (8.3%) State Hospital and one Private University Hospital participated in this survey. 94.3% of the centers had a bed capacity of 50 beds and over. Twenty-one (58.3%) centers had pediatric infection ward that followed febrile NP. All centers had an infection control committee. 25% (9/36) of the centers always followed pediatric neutropenic fever patients in a single room. 66.6% (24/36) of the centers had toilet in all patients’ room. the door features of patients’ room included mostly (94.1%, 32/34) manually opened door. Ten (27.7%) centers had hepa filter system, five of them had positive-negative pressure room. Thirteen (38.2%, 13/34) centers prefered hickmann catheter for accessing a patient’s central line. Training was given for catheteter care in all centers. Sixteen (44.4%) centers had determined policies about keeping toys in patient rooms. Visitor restrictions were performed in all centers. None of the centers allowed plants or flowers in hospital rooms. There was a neutropenic diet specific for pediatric NP provided in twenty-seven centers (75%). Conclusion: the prevention and control of infection contributes to the improvement of the prognosis of patients with hematological malignancies. Physicians must be aware of the infection risks and take precautions for infectious complications through the neutropenic period and standard protocols should be established and implemented for patients with hematological malignancies.Giriş: Maligniteli hastaların tedavi sürecindeki en önemli komplikasyonlardan biri enfeksiyonlardır. Nötropenik hastalarda enfeksiyon kontrolü ve izolasyon önlemleri için merkezden merkeze değişen farklı uygulamalar mevcuttur. Anket çalışmasının amacı Türkiye’deki bu farklılıkları ve ihtiyaçları belirlemektir. Gereç ve Yöntemler: Çok merkezli tanımlayıcı çalışmaya Türkiye’nin farklı coğrafik bölgelerinden pediatrik nötropenik hasta takip eden 36 merkez dahil edildi. Kemik iliği transplantasyon üniteleri çalışmaya alınmadı. Her merkezle en az üç kez iletişime geçildi. Anketi her merkezden iki doktor yanıtladı. Anket kişisel, genel hasta bakımı ve nötropenik hasta bakımını içeren 64 sorudan oluşmaktaydı. Bulgular: Çalışmaya katılan merkezlerin 20 (%55.5)’si üniversite hastanesi, 12 (%33.3)’si eğitim araştırma hastanesi, 3 (%8.3)’ ü devlet hastanesi ve bir tanesi de özel üniversite hastanesi idi. Merkezlerin %94.3’ünün yatak kapasitesi 50 yatak ve üzerinde idi. Yirmi bir (%58) merkezin çocuk enfeksiyon hastalıkları servisi mevcuttu. Tüm merkezlerin enfeksiyon kontrol komitesi vardı. Merkezlerin %25 (n= 9)‘inde nötropenik ateş (NPA) tanısı alan çocuk hastalar tek kişilik odalarda izleniyordu. Tüm odalarda tuvalet bulunan merkez sayısı 24 (%66.6) idi. Hasta odalarının büyük çoğunluğunda elle açılıp kapanır kapı (%94.1) ve musluk (%97.1) mevcuttu. on (%27.7) merkezin oda havalandırması için hepa-filtreli sistemi vardı. Beşinde negatif basınçlı oda mevcuttu. on üç merkezde kateter olarak hickman kateter tercih edilmişti. Tüm merkezlerde kateter bakımı için eğitim verilmekte idi. Hiçbir merkezde hasta ziyaretine ve hastane odasında bitki veya çiçek bulundurmaya izin verilmemekteydi. Merkezlerin %45.7’sinde hastanede oyuncak bulundurma ile ilgili hastane politikası vardı. Sonuç: Sonuç olarak, nötropenik hastaları enfeksiyondan korumak için hastanelerde çeşitli yaklaşımlar uygulanmaktadır. Rehberler belirlenip bu rehberler ışığında hastane koşulları düzenlenmeli ve nötropenik hasta izlemi yapılmalıdır

Pediatric Neutropenic Patients Care In Turkey

Objective: Infection is a common complication in children with malignancies. There is no consistent guidance for environmental infection control and isolation precautions for neutropenic patients (NP). There are differences between centers. The aim of this questionnaire study was to determine these differences in Turkey. Material and Methods: A multicenter-descriptive questionnaire was conducted on 36 centers from different geografical locations of Turkey. Bone marrow transplantation units were excluded. Each center was contacted at least three-times. Questionnaire was answered by two different doctors from each center. Results: Thirty-six centers including 20 (55.5%) University Hospitals, 12 (%33.3) Research Hospitals, three (8.3%) State Hospital and one Private University Hospital participated in this survey. 94.3% of the centers had a bed capacity of 50 beds and over. Twenty-one (58.3%) centers had pediatric infection ward that followed febrile NP. All centers had an infection control committee. 25% (9/36) of the centers always followed pediatric neutropenic fever patients in a single room. 66.6% (24/36) of the centers had toilet in all patients' room. The door features of patients' room included mostly (94.1%, 32/34) manually opened door. Ten (27.7%) centers had hepa filter system, five of them had positive-negative pressure room. Thirteen (38.2%, 13/34) centers prefered hickmann catheter for accessing a patient's central line. Training was given for catheteter care in all centers. Sixteen (44.4%) centers had determined policies about keeping toys in patient rooms. Visitor restrictions were performed in all centers. None of the centers allowed plants or flowers in hospital rooms. There was a neutropenic diet specific for pediatric NP provided in twenty-seven centers (75%). Conclusion: The prevention and control of infection contributes to the improvement of the prognosis of patients with hematological malignancies. Physicians must be aware of the infection risks and take precautions for infectious complications through the neutropenic period and standard protocols should be established and implemented for patients with hematological malignancies.WoSScopu