Kasem Bundit Engineering Journal

การหาค่าคงที่ของสปริงแบบคิวบิกของระบบระดับความเสรีขั้นเดียวไม่เชิงเส้น

ปริญญา บุญมาเลิศ; ธนู ฉุยฉาย — Mon, 29 Apr 2024 00:00:00 +0700

This research introduces a method for determining the parameter of cubic nonlinear springs by least square regression method. Calculations are conducted in both the time-domain and the frequency-domain. It was observed that both approaches yielded equally accurate results, regardless of whether the system exhibited over-damping or under-damping characteristics. In terms of computational time, the time-domain calculation proved to be approximately 10% faster than the frequency-domain calculation, with a theoretical calculation error of less than 10^-10%. Furthermore, it was discovered that the error was directly associated with the type of variables used. When employing double variables, the error remained within the range of 10^-10%, while using long double variables ensured that the error did not exceed 10^-12%.

พฤติกรรมของคานคอนกรีตเสริมเหล็กที่มีส่วนผสมของเศษยางจากยางรถยนต์รีไซเคิล

ปรัชญา ก้านบัว; ลาวัลย์ ขันเกษตร, อิทธิ ผลิตศิริ, ณัฐวุฒิ อินทบุตร — Mon, 29 Apr 2024 00:00:00 +0700

The objective of this research were study on the flexural behaviors of reinforced concrete beams made of concrete mixed with crumb rubber by testing 15 samples of beams. The beams sample had 15 centimeters wide, 25 centimeters depth and length of 2.4 meters from mixture of 5 ingredients, using crumb rubber as fine aggregate replacement in ratio of 5, 10, 15 and 20 percent by weight. According to the test, the beams behaved in two linear phases (bilinear) before non-linear until failure, the first crack occurred at 23-27 percent of the maximum load and entered the second phase until reaching the maximum load. After that, the beams were unable to support additional weight until failure. The study also reserved that to Increase amount of crumb rubber did not affect failure behavior of the beams but affect in flexural strength. The equation for calculating the Nominal moment can also be used for this type of beams, but the equation for calculating the cracking moment can only be used for beams that use crumb rubber in place of fine aggregate not exceeding 5%. For the beams with crumb rubber replacements from 10% to 20%, the cracking moment tested were only 80% of the value calculated from the equation. The maximum deflection and energy absorption tend to increase with amount of crumb rubber used to replace fine aggregate.

การปรับปรุงวิธีการทำงานในการตอกก้อนอินเสิร์ตสำหรับชิ้นส่วนชุดเฟืองเกียร์:กรณีศึกษาในบริษัทฉีดขึ้นรูปอะลูมิเนียม

จิรวัฒน์ วรวิชัย; กิตติ วิโรจรัตนาภาพิศาล, อุกฤษฎ์ ธนทรัพย์ทวี, อารุณี วงษ์ขาว — Mon, 29 Apr 2024 00:00:00 +0700

The objective of this research is to improve working methods of punch insert for part case gear after aluminum molding injection. The cause and effect diagram were used to define root cause of the proposed problems. It was found that the sub-cause was caused by the original method of knocking out the insert. There was a workpiece that had not been knocked out resulting in damage to the customer's tools if continue to machine the workpiece. Therefore, the new improved method of working was done by designing and setting up a method to punch the insert from the workpiece in the propeller assembly process as well as being able to check the workpiece simultaneously. These allow all workpieces with punch inserts to be removed. This can reduce a working step from 9 steps to 8 steps. Working time before improvement was 68.4 seconds per piece, after improvement was 58.3 seconds per piece, which is reduced to 10.1 seconds per piece, accounted for 14.76%.

การประมาณขนาดหม้อแปลงไฟฟ้าที่ใช้ในระบบจำหน่ายเชิงเศรษฐศาสตร์ให้เหมาะสมกับโหลดและลดกำลังไฟฟ้าสูญเสีย

บุญเลิศ สื่อเฉย — Mon, 29 Apr 2024 00:00:00 +0700

This research presents an economic estimation of the transformer size suitable for the distribution system to match the load and reduce power losses. It calculates the cost by combining the energy loss of the transformer with the transformer price. The parameter for the analyzation includes the initial price of transformer, the service life, the interest rate, the depreciation, the loss rate of transformer and the electricity energy rate per unit. The analyzation will calculate the cost to own transformer (COT) by varying the transformer capacities while keeping the load constant. In this research, the load for analysis is set at 350 kVA and a comparison is made among three transformer follow to PEA standard size: 400 kVA, 500 kVA and 630 kVA. The research finding indicate that the 630 kVA transformer has the lowest COT. The results of this study can serve as a guideline for selecting an appropriate transformer size for the load, help in deciding to choose a transformer to future load, help saving investment costs and effectively reduce energy expenses.

ผลกระทบของความชื้นต่อสมบัติทางกลของชิ้นงานในการพิมพ์ 3 มิติ ด้วยวัสดุไนล่อน 6

อุกฤษฏ์ ธนทรัพย์ทวี; มาโนช นำฟู, กิตติ วิโรจรัตนาภาพิศาล — Mon, 29 Apr 2024 00:00:00 +0700

This research studies the impact of moisture on the mechanical properties of 3D printed specimens from Nylon 6 (PA6). Nylon filaments were left in lab conditions for 5 different time periods prior to printing to absorb varied moisture levels. As the exposure time of the filaments in the lab atmosphere increased from 7 days to 35 days, higher amounts of moisture were absorbed by the nylon filaments [1]. After each exposure time period, the nylon filaments were printed to fabricate test specimens for evaluating tensile strength and impact resistance. The experimental results indicated that the exposure time of the filaments to ambient air affected the ultimate tensile strength and impact resistance of the test specimens. As the exposure time increased from 7 days to 35 days, the ultimate tensile strength and impact resistance progressively decreased. This suggests that as the nylon filaments were left in ambient lab conditions for longer periods, from 7 days to 35 days, they absorbed more moisture. The moisture absorption resulted in a 43.1% decrease in ultimate tensile strength, and a 29.2% decrease in impact resistance.