จำนวน Repository ( 3611 )
เครื่องกรองความถี่แบนด์พาสชนิดแอคทีฟที่ปรับตัวได้โดยใช้วงจรแทคโคมิเตอร์
This thesis presented the design and construction of an adaptive active band-pass filter by using a tachometer circuit. The main part was the multi voltage-mode filter circuit based on an operational transconductance amplifier which could automatically adjust the center frequency to adapt to the input signal frequency by the tachometer circuit. The frequency error value in the center frequency was set to be ≤ 3% of the input signal. Furthermore the proposed filter could support the input signal in the frequency range of 10 Hz - 10 kHz. From the simulation and experimental results of the proposed prototype filter it could respond to the frequency according to the theory of the band-pass filter and the error in choosing the center frequency which was 1.45 % and 2.6 % respectively (below the set error value of 3 %). Therefore the proposed filter could be used for real application. The working principles of the proposed prototype filter could also be applied to the noise attenuation circuit of an electrocardiogram machine. Moreover this research could be used as a guideline study for those who want to develop other types of adaptive active filters for higher efficiency.
การออกแบบล้อรันแฟลทสำหรับรถยนต์นั่งส่วนบุคคลด้วยระเบียบวิธีไฟไนต์เอลิเมนต์
The objective of this research was to design run flat wheels made of aluminum for passenger cars and investigate the stress strain and deformation of run flat wheels and their components. The original 17 inch run flat wheels were made of AISI 1020 steel with a weight of 11.3 kg per wheel. The main problems were from the high-level weight as well as the untighten connection together with noticed gaps taking place between the run flat wheel and the wheel. Therefore in this study the AISI 1020 material was changed to the Aluminum 6063 T6 material. The Numerical methodology using the finite element program was also chosen to indicate the comparative differences in the strain values engaged at various locations of both run flat wheels and pan wheels. The results obtained from both approaches using SolidWorks Simulation Program uncovered the consistent results of the experiments with a 10-16% difference in strain values. The complicated 17 inch wheel pan model was next built using reverse engineering and employed as a key reference to design the cross-sectional area of the new run flat wheels made of Aluminum 6063 T6. All these two parts could be connected tightly. The SolidWorks Simulation program was employed to design and examine the strength of both designed aluminum run flat wheels made of aluminum and the wheel pan made of 17 inch aluminum alloy to build passenger cars. The finite element model was furthermore applied for the run flat wheels made of aluminum 6063 T6 and it provided run flat wheels composed of 2 light weighted pieces. The stress strain and deformation measured were proven and suggested in the test. The output Von Mises stress did not exceed the Yield stress within the linear elastic limit and 3 times safety integrity value. The results from the study were that the obtained run flat wheels allowed the driver to continuously drive for a further 50 kilometers at a speed of 50 kilometers per hour without losing control. They allowed possible tire repairing or replacing when situated in a safe and convenient location.
การวิเคราะห์มุมเอียงและความหนาของแผ่นเกราะที่มีผลกระทบต่อการต้านทานการเจาะทะลุของกระสุนบนแผ่นเกราะอลูมิเนียมและสแตนเลส ด้วยระเบียบวิธีไฟไนต์เอลิเมนต์
This thesis was an analysis of the significance of angle of inclination and the thickness of the armor plate on the penetration resistance of bullets on aluminum and stainless steel armor plates determined by the finite element method. In this study the information results obtained from actual firing of bulletproof armor and the finite element simulation according to NIJ 3 standards were compared to create a pattern of bulletproof and bulletproof armor using the SolidWorks program. The simulation model of the armor shooting was created by the Ansys/Explicit Dynamics program. The bullet material was 7.62 mm tungsten carbide (WC). There were three plate types used in the simulation were made of different bulletproof armor materials: 1) stainless steel SUS304 using for the plate thickness of 5 6 8 10 14 20 30 40 45 and 55 mm. 2) aluminum AL7075 using for the plate thicknesses of 6 8 10 and 20 mm. Additionally 3) tungsten carbide using for the plate thicknesses of 6 8 and 10 mm. Each of these plates had a width x length of 300 x 300 mm. The simulation models were divided into two types: Type 1 a simulation firing at one plate at a time. Type II a simulation firing at two layered plates stacked together without any gaps between plates. The front and the back plates made of stainless steel and aluminum respectively or tungsten carbide and stainless steel respectively were determined. The angles of firing at bulletproof armor were set at 0 30 and 45 degrees. The output results were that in Type I the stainless-steel plate with a thickness of 30 mm or more could resist the penetration of bullets. However in Type II 2 stacked layers of the armor plates using the front stainless plate with a thickness of only 20 mm and the back aluminum plate with a thickness of only 8 mm could provide the same constructive results as those of tungsten carbide and stainless steel plates for the front and back plates with both thickness setting at 16 mm. All of them showed the resistance of the penetration to the bullets. More observation was that the increases in angles as a result enhanced more resistance of the bulletproof plates to bullet penetration.
การศึกษาสมบัติทางกลของโพลิเอทิลีนน้ำหนักโมเลกุลสูงยิ่งยวดเชิงประกอบสำหรับล้อ Run-flat
This research project aimed to test the mechanical properties and the capability in wear resistance of ultra-high molecular weight polyethylene composite as well as determine the optimal formulation of UHMWPE-based composites which had a main component of aluminum oxide. The developed formula was used in the manufacture of run-flat wheels and thus applied to build run-flat wheels with an understanding of the proper molding conditions under the run-flat wheel forming process. Two materials used in the research consisted of super-high molecular weight polyethylene (UHMWPE) as the base material and the additive of aluminum oxide (Al2O3). The parameters employed in the hot compression process to obtain the specimen for the experiment consisted of compressive force temperature time and the ratio between super-high molecular weight polyethylene and aluminum oxide. The test for mechanical properties consisted of an impact test a hardness test according to the ASTM D2240 standard a tensile test according to the ASTM D638 standard type I and a wear test according to the ASTM G77 standard. The results indicated that a hot compression condition under a pressure of 5 MPa a temperature of 210°C for 90 min and using 5% Al2O3 HTM 30 material caused mixed uneven powder particle sizes between 2 to 5 µm. The tensile test results inferred the yield strength of 20.52 MPa ultimate tensile strength at 29.96 MPa breaking strength at 22.83 MPa elongation at break at 265.8% and modulus of elasticity at 784.46 MPa. The highest hardness was 62 shore D the high impact strength was 586.8 J/m and it was displayed for the wear rate of hot compression specimens made of UHMWPE mixed with 5% HTM-30. Moreover it introduced a coefficient of friction the wear rate and the density of 0.12 8.66E-11 mm3/N.m and 1.2446958 g/cm3 respectively.
แผ่นเกราะโลหะกันกระสุน
This research project aimed to analyze and design the pattern of a bulletproof metal armor plate as well as build a bulletproof metal armor plate for a small armored regular truck. The methodology consisted of the NIJ standard test and the finite element analysis. The bulletproof plates created were tested for a real firing. Their firing results were compared with those of NIJ-standard using a finite element program in this case applying with the program Ansys/Explicit Dynamic. SolidWorks program is employed as a tool to design and create 3D models of armor plates and bullets. The materials taken in the finite element simulation were SKD11 and SUS304 and the parameters utilized in the research were material types hardness values spacing between the plates and thickness. In the case of two armor plates stacked SKD11 material was designed for the first armor plate to be hit by the bullet. It served to destroy bullets. In addition the second armor plate made of SUS304 material served to absorb energy and obstruct the movement of bullets. For testing a 30-06 caliber M2 AP 166 Gr bullet was selected at a 0-degree angle and the velocities measured and set by the Ansys/Explicit Dynamic program were 901.7 m/s and 880 m/s respectively. The front plate made of SKD11 material with a thickness of 10 mm and the back plate made of SUS304 material with a thickness of 10 mm were fired 1 shot. The results showed that the bullet could penetrate the front armor plate but not penetrate the back-armor plate. In the NIJ 3 standard tests the shooting with a 7.62x51 mm NATO FMJ 148 Gr shell at a 0-degree angle for 5 times with velocities equal to 846.4 841.3 839.1 838.2 and 845.3 m/s was performed on the stacking front and back armor plates both made of SUS304 material with a thickness of 8 mm. The bullet velocity simulated by the Ansys program was 847 m/s resulting in the front plate having a bullet penetration and a slight bulge on the back plate. From the finite element simulation results and the actual test results it was found that the damage to the armor plates detected by both methods was consistent. Therefore the finite element program was selected to simulate the damage of armor plates resistant to penetration according to the NIJ standard Level 4. The results of the research could be concluded that the use of armor plates stacked with suitable different materials in multiple layers would affect the penetration resistance. Increased thickness and optimal spacing between the armor plates were important parameters in penetration resistance. Moreover it revealed that the higher the material hardness the better its ability to resist penetration. In particular this suggestion should be applied to the first armor plate or front armor plate.