The critical buckling loads for various core densities and materials of honeycomb composite panels are experimentally and numerically investigated in this study. The surface plates of honeycomb composite panels are of polyester/glass fiber composite. Polyester resin-impregnated paper or aluminum is used as the honeycomb core material. Honeycomb panels with different cell sizes, but approximately the same volume, are produced and the effect of the honeycomb core density on the critical buckling load is investigated by compression tests. The critical buckling load of paper core panels is determined to be higher than that of aluminum core panels. It is seen that the buckling strength of the specimens increases by the increase of core density. As the critical buckling load exceeds a certain limit, regional core cell buckling and core crushing are seen in aluminum core panels. In paper core panels, regional cracks are seen, in addition to these failures. The study also calculates the numeric buckling loads of the panels using the ANSYS finite element analysis program. The achieved experimental and numerical results are compared with each other and the results are provided in tables.

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

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.

In the research for this contribution, the use of layered hybrid composites as materials for ballistic armor has been tested. As part of the study, ballistic tests of glass/aramid/carbon fiber laminated comp osite plates at different reinforcing angles, in various numbers and thicknesses were carried out and the results analyzed. Eight hybrid composite laminates, of various thicknesses 200 × 200 mm in size were produced by the hand lay-up method at angles of 0°, +/−45°. Plain and twill fabrics were used to analyze the ballistic performances at various fiber reinforcing angles. Ballistic tests were carried out at the Elazig Special Operation Branch Office, using a Beretta gun loaded with 9 mm FMJ (full metal jacket) bullets. These experiments with ballistic test equipment were conducted in accordance with international standards. During the ballistic experiments, the velocity and BFS (backface signature) was measured and evaluated. Test results suggest that five samples were successful according to NIJ 0101-06 standards. It was found that twill woven (TW) fabrics made for the study manifest a higher ballistic performance than plain-woven (PW) fabrics. UD (unidirectional), +/−45° UD fabrics were found to be more effective than 0° UD fabrics. The findings are indicative for the design of lightweight ballistic armor material.

Bu çalışmada, tabakalı hibrit kompozitlerin bireysel zırh malzemesi olarak kullanılabilirliği deneysel olarak araştırılmıştır. Çalışma kapsamında farklı fiber takviye açılarına, farklı tabaka sayılarına ve farklı kalınlıklara sahip Cam Fiber/Aramid Fiber/Karbon Fiber tabakalı kompozit plakaların balistik deneyleri yapılmış ve sonuçları incelenmiştir. Bu amaçla 200x200mm boyutlarındaki 30 tabakalı farklı kalınlıkta 4 adet plaka elle yatırma yöntemi kullanılarak üretilmiştir. Farklı fiber takviye açılarının balistik performansının incelenebilmesi için 0 o , 45 o , plain ve twill kumaşlar kullanılmıştır. Üretimi yapılan tabakalı hibrit kompozit plakaların balistik testleri Elazığ Özel Harekât Şube Müdürlüğü atış poligonlarında Beretta marka tabanca ile 9mm FMJ mermi kullanılarak yapılmıştır.