Melih Cemal Kuşhan

The effect of carbide particle additives on rheology of shear thickening fluids

In this paper, shear thickening fluids (STFs) including silicon carbide particles are presented. We fabricated a kind of STF based on nanosize fumed silica suspended in a liquid medium, polyethylene glycol, at a constant concentration of 20 wt.%. Then, different particle size silicon carbide (SiC) particles were added to the STF with various amounts. Their rheological properties under various temperatures were tested by using a rheometer. The suspension exhibits different systematic variations with respect to the varied parameters.

The effect of silicon carbide additives on the stab resistance of shear thickening fluid treated fabrics

ABSTRACT Applications of shear thickening fluids (STFs) with ballistic fabrics improve the protection performance of body protective systems. This article presents an innovative view of STF-impregnated ballistic fabrics by integrating silicon carbide (SiC) particles into targets. In this study, SiC particles were added into silica-based STFs, and Twaron fabrics were impregnated with this novel suspension. The effect of the SiC particles in the STFs was investigated with rheological testing. The results show that SiC particles are able to increase the viscosity profile of the suspension. In the stab testing, two types of impactors, such as spikes and knives, were dropped on the composite targets. According to the results, SiC particles enhance the protection performance of the STF-treated ballistic fabrics while keeping the flexibility.

ALLVAC 718 Plus™ Superalloy for Aircraft Engine Applications

Innovations on the aerospace and aircraft industry have been throwing light upon building to future’s engineering architecture at the today’s globalization world where technology is the indispensable part of life. On the basis of aviation sector, the improvements of materials used in aircraft gas turbine engines which constitute 50 % of total aircraft weight must protect its actuality continuously. On the other hand utilization of super alloys in aerospace and defense industries can not be ignored because of excellent corrosion and oxidation resistance, high strength and long creep life at elevated temperatures.

High Performance Fabrics in Body Protective Systems

High performance fabrics are preferable for armor systems due to their lightweight structure and flexibility. High performance fabrics are generally used in body armor design for personal protection. However, these fabrics are utilized to cover the living space in military vehicles such as helicopters and armored vehicles. Besides, pilot seats in combat helicopters are included in utilization area of high performance fabrics. On the other hand armor is defined as a defensive covering to protect body or something against attacking threats. Protection is provided by absorbing the kinetic energy of the attacking threats and stopping them before any damage occurs in the target. This paper offers an overview of high performance fabrics in armor systems.

State-of-Art Technology ALLVAC 718 Plus Superalloy for Gas Turbine Engine Parts

Innovations on the aerospace and aircraft industry have been throwing light upon building to future’s engineering architecture at the today’s globalization world where technology is the indispensable part of life. On the basis of aviation sector, the improvements of materials used in aircraft gas turbine engines which constitute 50 % of total aircraft weight must protect its actuality continuously. Utilization of super alloys in aerospace and defense industries can not be ignored because of excellent corrosion and oxidation resistance, high strength and long creep life at elevated temperatures. The newly innovated ALLVAC 718 Plus superalloy which is the last version of Inconel 718 has been proceeding in the way to become a material that aerospace and defense industries never replace of any other material with combining its good mechanical properties, easy machinability and low cost. However because it is a newly developed superalloy, in present paper its properties including chemistry, microstructure, strengthening mechanisms, weldability and cost will be discussed and the superiority of the ALLVAC 718 plus will be addressed.

Fatigue and corrosion behavior of in-service AA7075 aircraft component after thermo-mechanical and retrogression and re-aging treatments

Fatigue crack growth and corrosion are the two important failure mechanisms for aircraft structural components and, therefore, various treatments have been developed to improve the fatigue and corrosion resistance of aircraft materials. In the present study, thermo-mechanical and retrogression and re-aging treatments were applied to AA7075T7352 specimens, which were extracted from a nearly 40 years in-service F-4 Phantom component. The in-service component was selected in order to observe the influence of thermo-mechanical and retrogression and re-aging treatments on the properties of a used aircraft material and it was expected that the service life of the material is extended in the maintenance stage. In the experimental work, electrical, mechanical, fatigue crack growth, and corrosion tests were carried out using the specimens with T7352 (as-received), thermo-mechanical and retrogression and re-aging conditions. Based on the results, fatigue crack growth resistance of the material benefited from the thermo-mechanical and retrogression and re-aging treatments; however, both treatments lowered the corrosion resistance of the material.

Fatigue failure in aircraft structural components

Abstract Safety in aircraft applications is at the advanced level since any mistake may result in irreversible situations during the services. For this reason, aircraft structural parts are subject to different kinds of inspections from manufacturing stage to service stage. Generally, the parts under arduous conditions are called critical parts and inspected profoundly against the fatigue defects. The most common fatigue failures arise from sharp edges, notch-sensitive areas, and necked-down sections in the structural parts. In this chapter, two case studies about failure of aircraft structural components are discussed. The first case study describes the fracture mechanism in a Cessna-185 aircraft propeller blade due to fatigue crack propagation induced by foreign object damage. The second case study explains the fatigue failure of a cylindrical part in an aircraft flap actuator.

Wireless Eddy Current Probe Prototype and Monitor Design and Aircraft Maintenance Applications

Eddy current testing method has a wide usage in the field of Industry. Especially, aircraft maintenance field has so many applicable areas for this method. In addition, a wide variety of inspections and measurements may be performed easily with the eddy current method. More effective and flexible operation conditions were reached by designing wireless eddy current probe prototype for all aircraft maintenance inspections. Prototype probe design, the advantages of use of this probe in aircraft maintenance applications and inspections performed as wireless were studied in this paper.

New Strategies for Improvement of Structural Gas Turbine Engine Parts

In this study, the basic limitations of superalloys in high temperature performances will be explained and then after giving the important properties of MoSi2 such as oxidation behaviour at relatively low temperatures (500°C-700°C) , some interesting composites of this material will be discussed as a candidate structural material in gas turbine engines.

The Effect of Laser Glazing on High Temperature Oxidation Resistance of Thermal Barrier Coatings

Thermal barrier coatings (TBCs) have been widely used by aero and land based gas turbines to protect hot section parts from oxidation and thermal loads. These coatings are generally consisting of multiple layers of coating (usually two) with each layer having a specific function. TBCs are generally deposited with air plasma spray (APS) or electron beam physical vapor deposition (EB-PVD) techniques. In this paper plasma sprayed TBCs were deposited on to 304 stainless steel substrates then ceramic surfaces were glazing with Nd-YAG laser. Metallographic examinations were applied to the samples to investigate microstructural changes in glazed ceramic layer. Both glazed and as-coated samples were subjected to oxidation tests to measure the high temperature oxidation resistance. The tests showed that, laser glazing is beneficial to oxidation resistance of TBCs. This improvement is attributed to sintering of zirconia layer which act as oxygen barrier and formed during glazing process.