| Composites are widely applied in many state-of-the-art weapons and equipment as well as the aerospace engineering. As a new type of material with numerous good qualities such as light weight, high strength and strong resistance against corrosion, fatigue and high temperature, composite is gradually threatening traditional material’s leading position in application fields. However, there are a lot of difficulties to be resolved in its manufacturing and processing technology. And the research concerning its processing mechanism is far from mature. This paper is designed to study and analyze the drilling process of glass-fiber reinforced composite so as to provide technical support for its further promotion and application. The main contents and conclusions are organized as follows:(1) Analysis on glass-fiber reinforced composite’s intrinsic and mechanical characteristics mainly covers the features of glass fiber, the chemical and physical properties of glass-fiber reinforced composite and its commonly-used molding process as well as composite elastic mechanics and composite layer board failure criterion.(2) Based on the orthogonal cutting theory and research of drilling process, a simplified drilling model was obtained. Then by analyzing the stress of drilling tool, the stress of glass fiber of its position at center of the bit, the main cutting edge location of the bit and peripheral glass fiber of the bit, it came to a series of conclusions: when the fiber direction angle and the cutting direction are between 0??? ?90?, the cutting surface is relatively flat and the fracture is smooth and when they are between 90??? ?180?, the cutting surface is rough and the fracture is bent due to bending stress. If the perpendicular force is strong enough, the glass fiber will be twisted and may produce oblique fracture out of combined cutting force. As can be seen from scanning electron microscope, there are mainly three types of fractures: smooth fracture, bending fracture and oblique fracture. The relation of glass fiber stress and the fracture type is obvious.(3) By way of finite element analysis technology, drilling process of glass fiber reinforced composite was simulated. After taking Abaqus/Explicit module as simulation model and conducting simulation tests on different parameters, a conclusion was drawn: the drilling axial force grows weak with the increase of spindle speed but grows strong with the increase of feed rate and the bit diameter. After specific research on drilling process at 2000r/min and 120mm/min, and the damage process of glass fiber reinforced composite according to Hashin Damage Rule, the analysis moved forward on fiber and matrix stress during the process of drilling with the post-processing module, from which it could be found that the fiber angles and the stress were in the same direction. And the failure process of matrix happened ahead of the glass fiber which turned out to be in line with actual situation. Therefore, the simulation model is effective.(4) Through selecting samples and analyzing the cutting force of glass fiber reinforced composite on Kislter force measuring device, the research was conducted to analyze the drilling force under different process parameters from which a conclusion was gained: the drilling axial force is proportional to the bit diameter and feed rate, but is inversely proportional with the spindle speed. The result complies with the simulation tests. At last, in the drilling experiments, surface quality in the process of drilling hole wall was studied and the processing typical defects of different positions were summarized, which revealed that the common defect is ladder at the export and entrance of glass fiber reinforced composite and poor roughness and stratification often occur in the internal of glass fiber reinforced plastics. |
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