No abstract

Weight is of great importance in the aircraft industry. Aircraft are made of aluminum alloys that are susceptible to heat treatment, because they are light in weight and are metal strong enough for the dynamic designed loads they can face, but there are other reasons for obtaining alternative materials, and these materials are composite materials that it is lighter in weight than aircraft made of aluminum, firstly, and secondly, it can be formed into attractive shapes, eliminating welding and rivets, and thirdly, it can be formed into aerodynamic shapes. This work is based on designing a three-dimensional model consisting of aluminum alloy (AA-6061-T6) of the structure helicopter and then comparing it with five other models of different metal and composite materials to obtain a structure that has the least weight among these models. The results indicate that the best model with the lowest weight is the fourth model consisting of carbon fiber, proportions and weight of a square meter and a thickness of (28 mm) than the weight of the first model consisting of aluminum and weighing (81 kg), it was less than (22.7%). Then the fifth model, which consisted of an outer layer of aluminum with a thickness of five millimeters and another inner layer of aluminum of the same thickness, and between the inner and outer layer eighteen layers of carbon fiber, where the percentage of decrease in it compared to the first model by up to (19.2%), and worse a model in terms of weight is the second model was made of steel, which has a weight that is almost twice the weight of the first model.

In this paper, the amount of excess weight resulting from the design of a mathematical model composed of composite materials will be calculated and compared with a mathematical model of an armored steel structure. Five different models were designed, one of which is made of steel, the other part is made of composite materials, and a section of steel and composite materials, and then tested for resistance to stresses and compared the weight of each structure with that of the steel component by taking the maximum stress as a basic criterion for weight comparison. The results showed that the best model was the second model fiberglass, where the percentage of weight loss was compared to the steel model (73.77%), in addition to the wall thickness (62 mm) and the wall thickness of the steel model with which the comparison was (60 mm), but the displacement is (7. 24 mm), and in the steel model it is (1.827 mm). The best model compared to steel in terms of resistance to maximum stress, less displacement and less weight was the model consisting of steel with carbon fiber and its thickness was (47 layers& 57 mm, 2 layer & 10 mm steel and 45 layer & 45 mm carbon fiber), and the percentage of weight loss compared to the first mathematical model (60.96%). The results of this research may be a key to obtaining alternative materials for traditional materials in the manufacture of armored hulls, aircraft and ships, and it has a lower weight.

Aluminum is one of the most commonly used alloys in industrial applications due to its significant qualities such as resistance to wear, high hardness resistance, and high conductivity. This study will concentrate on the hardness resistance of two dissimilar aluminum alloys at different rotational and travel velocities, where the behavior of the alloys' hardness resistance will be studied after the welding process, from the welding center to the alloys' edges, and this will be done in three areas. Due to temperature changes at the weld in these three separate regions, the first area was at the start of the welding process, the second in the midst of the model, and the third area was at the conclusion of the welding process, to examine the influence of temperature on the hardness resistance. The results showed that increasing the travel velocity of the feed cart and keeping the rotational velocity constant increased the hardness resistance, whereas increasing the rotary tool velocity and keeping the travel velocity of the feeding cart constant decreased the hardness resistance of the two welded alloys. The maximum hardness resistance recorded in the model's welding center (3-3) and its value were more than (49.47 percent) the lowest hardness resistance recorded for all models, which was for the model (7-1).