Numerical and experimental study of the effects of center holes located at opposite sides on dynamic axial crushing of thin-walled square aluminum extrusions column are presented in this paper. The results showed that, by inserting the holes, the impact energy absorption characteristic in a progressive buckling can be improved as the starting location of the plastic deformation is always from holes and peak crush force can be decrease, so that the deceleration does not exceed the limit that can injure the passenger when frontal impact occurs. Here, the results of numerical simulations, conducted using an explicit finite element code, are compared with experimental results for various hole diameter. The results shows that the peak crushing force is decrease, while the mean crushing force is relatively constant.
Aircraft are currently quite popular transportation, due to its ability to utilize air space as a flight path, so that it can be efficient in mileage. To support the safety of airplane passengers, every component on the aircraft must pass the test. One of them in the aircraft windshields that are prone to collisions with other objects. In accordance with the regulations in the Civil Aviation Safety Regulation (CASR) the windshield must withstand the impact load of a 0,91 kg bird. In this simulation, the material shape of the bird uses the EOS Tabular type. For modeling windshields, frame¸ gaskets and birds use a general method for solid materials, namely the Lagrangian method. Rubber used as gasket material with mooney rivlin for modeling material behavior. the polymethyl methacrylate and aluminum alloy 7075 T6 material is used in the windshield and frame. Numerical modeling is validated using analytical results. The gasket thickness of 2 mm produces the most optimum energy absorption. The use of gaskets on the windshield does not have a significant effect on the windshield because the gasket on average is only able to absorb 5% of the total energy absorbed by all windshield parts. The collision parameter that produces the greatest failure occurs at a speed of 87,5 m/s with -15o angle. The area that is most prone to material failure is in the area of the upper bolt hole.
This research studies influence of bird geometry on impact pressures during bird strike, namely Hugoniot and Stagnation pressure through initial modelling by numerical simulations. Bird geometry is capsule or cylinder with hemisphere end. The geometry is simulated with different L/D ratio, 1.4, 1.6, 1.8 and 2.0. Elastic-plastic hydrodynamic material model is used in simulation. Bird model simulations are using lagrangian method and initial velocities are 200 m/s. The results show variation of L/D ratio provide Hugoniot pressure 10-19 times higher than stagnation pressure in
Penelitian ini mempelajari pengaruh geometri burung terhadap tekanan impak pada kasus tabrak burung, yaitu tekanan hugoniot dan stagnasi. Geometri burung berbentuk capsule atau silinder dengan kedua ujung setengah bola. Geometri disimulasikan dengan rasio L/D yang berbeda yaitu 1,5; 1,7; dan 1,9. Model material burung elastis, plastis, hidrodinamik digunakan pada simulasi. Simulasi model burung dilakukan dengan metode Smooth Particle Hydrodynamics (SPH) pada variasi kecepatan 100 m/s, 200 m/s, dan 300 m/s. Hasil simulasi menunjukkan dengan variasi rasio L/D diperoleh nilai tekanan Hugoniot jauh lebih tinggi sekitar 14-25 kali lipat tekanan stagnasi pada L/D = 1.5, 12-25 kali pada L/D = 1.7, dan 11-34 kali pada L/D = 1.9. Tekanan Hugoniot menunjukkan nilai yang meningkat dari L/D 1.5 sampai 1.9 pada kecepatan 100 m/s. Namun, untuk tekanan Hugoniot pada kecepatan 200 m/s menunjukkan nilai yang menurun dari L/D 1.5 sampai 1.9. Tekanan stagnasi rasio L/D 1.9 lebih rendah dibandingkan L/D 1.5 dan 1.7 pada kecepatan impak 100 dan 200 m/s.
Car accidents have increased significantly for countries that have high gross domestic product (GDP) [1]. This has fatal consequences for passengers, especially if there is an accident at the front of the vehicle [3]. To minimize the impact of accidents on the front of the vehicle, the bumper system on the vehicle must be designed as well as possible. The bumper system is equipped with an collision absorbing system called the crash box. This system is mounted on the front and rear part of the vehicle and consist of a frontal bar and longitudinal members. Longitudinal members have the shape of thin walled tubes. During collision, the frontal bar is directly in contact with the source of impact energy and it distributes the load to the thin walled tube. The thin walled tube will receive the peak crushing force from the source of collision energy and absorb the energy by plastic deformation. The deformation behavior of the thin walled tube determines the crashworthiness of the vehicle. In the crushing box design, the thin walled tube can be given discontinuity in the form of a circular hole has been done by previous reseachers to find out how much peak force caused by collision with some variations. In this research, numerical analysis conducted using the thin walled tube with ellipse discontinuity by varying the ratio of ellipse hole in the crushing box to D/
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