http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Mohammad Mehdi Nejadi (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
-
Mohammad Mehdi Nejadi,Mehdi Mohammadimehr 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.3
In the present study, according to the important of porosity in low specific weight in comparison of high stiffness of carbon nanotubes reinforced composite, buckling and free vibration analysis of sandwich composite beam in two configurations, of laminates using differential quadrature method (DQM) is studied. Also, the effects of porosity coefficient and three types of porosity distribution on critical buckling load and natural frequency are discussed. It is shown the buckling loads and natural frequencies of laminate 1 are significantly larger than the results of laminate 2. When configuration 2 (the core is made of FRC) and laminate 1 ([0/90/0/45/90]s) are used, the first natural frequency rises noticeably. It is also demonstrated that the influence of the core height in the case of lower carbon volume fractions is negligible. Even though, when volume fraction of fiber increases, the critical buckling load enhances smoothly. It should be noticed the amount of decline has inverse relationship with the beam aspect ratio. Investigating three porosity patterns, beam with the distribution of porosity Type 2 has the maximum critical buckling load and first natural frequency. Among three elastic foundations (constant, linear and parabolic), buckling load and natural frequency in linear variation has the least amount. For all kind of elastic foundations, when the porosity coefficient increases, critical buckling load and natural frequency decline significantly.
-
Nejadi, Mohammad Mehdi,Mohammadimehr, Mehdi Techno-Press 2020 Advances in nano research Vol.8 No.1
In the present study, buckling analysis of sandwich composite (carbon nanotube reinforced composite and fiber reinforced composite) Euler-Bernoulli beam in two configurations (core and layers material), three laminates (combination of different angles) and two models (relative thickness of core according to peripheral layers) using differential quadrature method (DQM) is studied. Also, the effects of porosity coefficient and different types of porosity distribution on critical buckling load are discussed. Using sandwich beam, it shows a considerable enhancement in the critical buckling load when compared to ordinary composite. Actually, resistance against buckling in sandwich beam is between two to four times more. It is also showed the critical buckling loads of laminate 1 and 3 are significantly larger than the results of laminate 2. When Configuration 2 is used, the critical buckling load rises about 3 percent in laminate 1 and 3 compared to the results of configuration 1. The amount of enhancement for laminate 3 is about 17 percent. It is also demonstrated that the influence of the core height (thickness) in the case of lower carbon volume fractions is ignorable. Even though, when volume fraction of fiber increases, differences grow smoothly. It should be noticed the amount of decline has inverse relationship with the beam aspect ratio. Among three porosity patterns investigated, beam with the distribution of porosity Type 2 (downward parabolic) has the maximum critical buckling load. At the end, the first three modes of buckling will be demonstrated to investigate the effect of spring constants.
-
Nejadi, Mohammad Mehdi,Mohammadimehr, Mehdi,Mehrabi, Mojtaba Techno-Press 2021 Advances in nano research Vol.10 No.6
Sandwich structures made of composites are widely applicable in different industries, including aerospace and power plants. The combination of a porous sandwich with functionally graded materials makes structures more resistant to analyze buckling and vibration behaviors. According to its high surface area and high strength, adding graphene platelets to the composite increases the final mechanical properties of composites. In the present paper, the effect of volume fraction distribution of fibers, numbers, and angles of layers in composites will be investigated. Additionally, the different porosity coefficients and distribution along the beam length will consider and the best porosity distributions will identify. Pasternak elastic foundation is considered during the beam length as linearly and parabolically. The equations of motion for the Timoshenko sandwich beam are solved by the differential quadrature method (DQM). The influences of adding graphene platelets with three various patterns on critical buckling load and natural frequency of composite beam will investigate. Also, the buckling and vibration behaviors of pure composites, perfect composite and FGM (Functionally Graded Material) composites will compare. Moreover, the critical buckling load will obtain by the Mori-Tanaka model.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
