• 한국자동차공학회논문집
• /
• 제14권4호
• /
• pp.12-19
• /
• 2006

It is positively necessary to study on the stiffness of a 13degree-type impact tester in order to improve the fracture prediction of impact testing in wheels using FE(finite-element) analysis. The 13degree-type impact tester consists of an impact striker, a wheel fixer, a steel plate, and four cylindrical rubbers. Important parts of the tester are the steel plate and four cylindrical rubbers which play a role of absorbing impact energy during impact testing. Because of these buffers, the RF(reaction force) variation of the lower part in the 13degree-type impact tester showed the tendency like a damped harmony oscillation during impact testing. In order to investigate the stiffness of a 13degree-type impact tester, this work measured each stiffness of a steel plate and cylindrical rubbers. The stiffness of a cylindrical rubber was measured using a compressive tester. On the other hand, the stiffness of a steel plate was predicted by simulating experimental method using FE analysis.

• 동력기계공학회지
• /
• 제21권5호
• /
• pp.29-34
• /
• 2017

Many household appliances, including vacuum cleaners, are being subjected to various of impact damages, and made of plastic. However, researches on the damage of appliances materials by repetitive impacts have been rarely conducted. the mechanical stress exerted upon impact-modified polycarbonate (PC) has a great influence not only on the quality of the product but also on the life span. The purpose of this research was to quantify the effects of repetitive impact on the polycarbonate. Second, it was to design the repetitive impact tester for controlling the impact energy. The mechanical properties of tensile strength, yielding stress and strain on the specimens subjected to cyclic impacts were discussed. Tensile strength was sharply declined at the beginning of the impact cycles, while the strain gradually decreased during impact cycles.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 춘계학술대회 논문집
• /
• pp.865-868
• /
• 2002

This study investigated the shape deformation of ball projectile(5.56mn) under the low energy impact by the use of the drop weight impact tester. ball projectile(5.56mm) consisted of the copper face with a lead core. The impact conditions were changed with the variations of the mass and the drop height of the impact tup. Shape deformation of ball projectile(5.56mm) after low velocity impact was measured using a video microscope and CCD camera. The test result showed that impact energy by changing of drop height of the impact tup affected shape deformation of ball projectile(5.56mm). So, it is important to study the relativity between shape deformation of ball projectile(5.56mm) and ballistic protection of plate(such as hybrid composite laminates) under the high velocity impact.

• 한국자동차공학회논문집
• /
• 제9권3호
• /
• pp.210-220
• /
• 2001

This paper aims at the evaluation on the characterization of CFRP laminate plates using falling weight impact tester. The experimentation was conducted on several laminates of different fiber and ply orientation. A system was built for the impact strength of CFRP laminates in consideration of stress wave propagation with using drop-weight impact tester as one of impact test. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that or quasi-isotropic specimen over impact energy 7J, but in case or using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed or stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. It is found that influence was confirmed between impact energy and absorbed energy as the impact energy is increased with adding the falling weight.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
• /
• pp.85-88
• /
• 2002

We have implemented a system of falling weight impact tester. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that of quasi-isotropic specimen over impact energy 7J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed of stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. Delamination area of impacted specimens was measured with ultrasonic C-scanner to find correlation between impact energy and delamination area. Delamination area and frequency responses was evaluated between impacted and unimpacted specimens. There is a strong correlation between frequency responses and impact-induced delamination. The presence and scale of damages have been investigated based on the variations of frequency responses.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2000년도 추계학술발표대회 논문집
• /
• pp.106-109
• /
• 2000

Impact tester was build up to evaluate the characterization of CFRP laminate plates under the low velocity impact. The tests were conducted on several laminates of different ply orientation A system was budded for the impact strength of CFRP laminates in consideration of stress wave propagation theory using drop-weight impact tester as one of impact test. Results indicate that absorbed energy of quasi-isotropic specimen having four interfaces is higher than that of orthotropic laminates with two interfaces. Also the damage area was measured with ultrasonic C-scanner on some samples. In the specimens the relationship was linear between damaged area and absorbed energy to some degree. Absorbed energy in the specimen that ply number, interface number and fiber stacking sequences is same but having hybrid is higher than that of orthotropic laminates without hybrid.

• Composites Research
• /
• 제23권1호
• /
• pp.8-16
• /
• 2010

섬유금속 적층판(FMLs)은 손상허용도를 향상시키고 무게를 줄이는데 적합하여 항공우주 응용의 신소재로 각광을 받고 있다. 본 연구에서는 우선 섬유와 알루미늄을 이용하여 적층판을 제조하여 인장시험을 수행 후 FMLs의 기계적 물성을 평가하였다. 또한 알루미늄과 섬유적층의 변화를 주어 낙추충격시험기(Drop Weight Impact Tester)를 이용하여 저속충격하에서 낙추 높이를 조절하여 각 종류의 시험편 마다 충격시간에 따른 하중과 충격흡수에너지를 각각 비교하였다. 추가로 유한요소해석을 이용하여 시험조건과 동일 조건하 인장과 충격거동해석을 수행한 결과를 실험치와 비교하여 실험과 이론해석이 잘 일치함을 보였다.

• 한국안전학회지
• /
• 제14권3호
• /
• pp.12-17
• /
• 1999

In this study, a drop-weight impact tester was manufactured to assess the strength of CFRP laminate plates. The tests were conducted on several laminates of different ply orientation. A system for the impact strength of CFRP laminates was made considering stress wave propagation theory using drop-weight impact tester as one of impact test. Results indicate that absorbed energy of quasi-isotropic specimen, haying four interfaces is higher than that of orthotropic laminates with two interfaces. Absorbed energy in the specimen that ply number, interface number and fiber stacking sequences is same but having hybrid is higher than that of orthotropic laminates without hybrid.

• 한국기계가공학회지
• /
• 제15권3호
• /
• pp.44-51
• /
• 2016

This paper presents the characteristics of the energy absorption in an expansion tube type impact absorber that is applied to a high weight drop tester and the use of a response surface methodology to predict the impact energy absorption. In order to identify the characteristics of the energy absorption, a set of finite element analysis was conducted with Abaqus Explicit. Moreover, the ISCD-II sampling method and a first order polynomial were used to build a response surface. As a result, we demonstrated that the impact energy could be controlled by four main design variables, namely an expansion pipe's thickness, inner radius, pressing die's expansion angle and expansion ratio. Additionally, we observed the relationship between the four main design variables and the impact energy absorbing time, displacement, and maximum impact force.

• 항공우주시스템공학회지
• /
• 제10권2호
• /
• pp.34-40
• /
• 2016

A satellite is exposed to various impact environment until orbit entry. It is particularly undergoing the biggest impact by pyro shock, which is generated when the launch vehicle stages are separated or the satellite is separated from the launch vehicle. In this paper, due to the fact that the pyro shock is prerequisite for performing the test and verification on the ground, we developed an air-gun type shock tester for NEXTSat-1 shock test at the KAIST SaTReC along with the development of program introduced by LabVIEW software. The program operated in shock tester is consist of data measurement and analysis with the convenient implementation of user interface and its easy modification of the code.