Pim bağlantılı tabakalı kompozit levhalarda ilerlemeli hasar analizi
Yükleniyor...
Tarih
2012
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Dicle Üniversitesi Mühendislik Fakültesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Sunulan çalışmada, pim bağlantılı kompozit levhaların hasar davranışları deneysel ve sayısal yöntemler
kullanılarak araştırılmıştır. Kompozit malzeme olarak tek yönde karbon fiber kullanılarak takviye edilmiş
epoksi matriks reçineli [0o
/75o
]2 simetrik ve anti-simetrik tabaka dizilimine sahip levhalar kullanılmıştır.
Sıcak presleme tekniği kullanılarak üretilen kompozit levhalarda epoksi reçine olarak %80 oranında CY 225
epoksi reçine ve %20 oranında Hy 225 sertleştirici kullanılmıştır. Presleme işlemi sonunda dört tabakadan
oluşan 1,235 mm kalınlığında kompozit levhalar elde edilmiştir. Kompozit levhaların mekanik özellikleri
ASTM standartlarına göre belirlenmiştir. Geometrik parametrelerin değişimi; pim deliği merkezinin
levhanın serbest kenarına uzaklığının pim deliği çapına oranı E/D ve levha genişliğinin pim deliği çapına
oranı W/D değerlerine göre incelenmiştir. Pim deliği çapı 6 mm olmak üzere, E/D oranı 1’den 5’e kadar
arttırılırken, W/D oranı 2’den 5’e kadar arttırılmıştır. Sayısal çalışma, ANSYS 11.0 programında üç
aşamadan oluşan bir alt program yardımı ile gerçekleştirilmiştir. Ansys parametrik dizayn dili
(APDL)kullanılarak hazırlanan programda öncelikle katı modelleme, sonlu elemanlara bölmeleme ve sınır
şartlarının teşkili, ikinci bölümde gerilme analizi ve son bölümde ise hasar analizi yapılmıştır. Hasar
analizinde, hasar yüklerini belirlemek için Hashin hasar kriteri kullanılırken hasar tipleri ve son hasar yükü
malzeme indirgeme kuralları kullanılarak belirlenmiştir. Çalışma sonucunda hasar tiplerinin ve yüklerinin
değişiminde E/D oranının etkili olduğu gözlemlenmiştir. E/D oranın 1 olduğu tüm numuneler için hasar tipi
olarak kesme hasarı görülürken 2, 3, 4 ve 5 olduğu numunelerde ezilme hasarı görülmüştür. Sayısal ve
deneysel sonuçlar arasında %1 ile %14 oranında değişen yakınsaklıkta sonuçlar elde edilmiştir.
Fiber reinforced composite plates are widely using automotive, aerospace and space craft industry. For joining composite to composite or composite to metal, mechanical fasteners are used. Pinned connections are a kind of mechanical fasteners and using commonly for joining composites. It is preferred because of low cost, simplicity for application, cheaper than other fasteners and facilitation of disassembly for repair. For application of pinned connections a hole must be opened in the composite plates. Then, the stress concentration locations are appeared on the edge of the hole. The hole is causes stress concentration locations and often causes reduction of load capacity of composite plates. Because of complex failure modes of mechanical joints, designer must be have much more rigorous design knowledge and techniques than traditional methods. In the present sudy, failure behaviour of pinned joint composite materials were analysed experimentally and numerically. The composite materials which were consist of unidirectional carbon fibers and epoxy matrix resin were used with [0o /75o ]2 symmetric and anti symmetric laminae layups. Numerical analysis was performed with using three dimensionally finite element methods in ANSYS software. In the progressive failure analysis, the Hashin failure criteria and material properties degradation rules were used for predicted failure loads and failure modes. The composite plates produced in IZOREEL firm by supporting FUBAP (Firat University Scientific Research Unit). All laminates were manufactured by press-mould technique. As the matrix material, epoxy CY 225 and hardener HY 225 are mixed in the mass ratio at 100:80. Volume fraction of unidirectional carbon fiber is approximately 70 %. A serial of experiments was performed for determining failure behavior of pin joined and mechanical properties of carbon/epoxy composite plates. The pin loading tensile tests were performed according to ASTM D 953-D standard test method. The failure analysis was performed in ANSYS finite element software with using a computer code which was created with APDL codes. The stress analysis is ended; the stress component of each element is saved in the matrix form. Then each element is tested with failure criteria. If a failure is predicted on any element, material properties are modified by implementing degradation rules. This iteration is continued until catastrophic failure appears. All of the specimens were loaded until catastrophic failure occurred and the general behavior of the composite plates was obtained from the load/displacement curves. The shear-out failure mode was observed for pin displacement value between 0,5-1,5 mm and the bearing failure mode was observed for pin displacement value between 1- 3 mm. Generally, the failure loads affected the geometrical parameters (E/D and W/D). The failure loads were increased with increasing E/D and W/D ratios. However, in this study the failure modes varied with E/D ratios. When E/D ratios were equal 1, the failure mode was observed as shear-out mode. For other values of E/D ratios (i.e. 2, 3, 4, 5), the failure modes were observed as bearing failure. Because of the fiber orientation angle (0o) of composite plates, failure modes of pinned connections were not impressed the W/D ratios and the net – tension failure was not observed.
Fiber reinforced composite plates are widely using automotive, aerospace and space craft industry. For joining composite to composite or composite to metal, mechanical fasteners are used. Pinned connections are a kind of mechanical fasteners and using commonly for joining composites. It is preferred because of low cost, simplicity for application, cheaper than other fasteners and facilitation of disassembly for repair. For application of pinned connections a hole must be opened in the composite plates. Then, the stress concentration locations are appeared on the edge of the hole. The hole is causes stress concentration locations and often causes reduction of load capacity of composite plates. Because of complex failure modes of mechanical joints, designer must be have much more rigorous design knowledge and techniques than traditional methods. In the present sudy, failure behaviour of pinned joint composite materials were analysed experimentally and numerically. The composite materials which were consist of unidirectional carbon fibers and epoxy matrix resin were used with [0o /75o ]2 symmetric and anti symmetric laminae layups. Numerical analysis was performed with using three dimensionally finite element methods in ANSYS software. In the progressive failure analysis, the Hashin failure criteria and material properties degradation rules were used for predicted failure loads and failure modes. The composite plates produced in IZOREEL firm by supporting FUBAP (Firat University Scientific Research Unit). All laminates were manufactured by press-mould technique. As the matrix material, epoxy CY 225 and hardener HY 225 are mixed in the mass ratio at 100:80. Volume fraction of unidirectional carbon fiber is approximately 70 %. A serial of experiments was performed for determining failure behavior of pin joined and mechanical properties of carbon/epoxy composite plates. The pin loading tensile tests were performed according to ASTM D 953-D standard test method. The failure analysis was performed in ANSYS finite element software with using a computer code which was created with APDL codes. The stress analysis is ended; the stress component of each element is saved in the matrix form. Then each element is tested with failure criteria. If a failure is predicted on any element, material properties are modified by implementing degradation rules. This iteration is continued until catastrophic failure appears. All of the specimens were loaded until catastrophic failure occurred and the general behavior of the composite plates was obtained from the load/displacement curves. The shear-out failure mode was observed for pin displacement value between 0,5-1,5 mm and the bearing failure mode was observed for pin displacement value between 1- 3 mm. Generally, the failure loads affected the geometrical parameters (E/D and W/D). The failure loads were increased with increasing E/D and W/D ratios. However, in this study the failure modes varied with E/D ratios. When E/D ratios were equal 1, the failure mode was observed as shear-out mode. For other values of E/D ratios (i.e. 2, 3, 4, 5), the failure modes were observed as bearing failure. Because of the fiber orientation angle (0o) of composite plates, failure modes of pinned connections were not impressed the W/D ratios and the net – tension failure was not observed.
Açıklama
Anahtar Kelimeler
Kompozit levhalar, İlerlemeli hasar analizi, Pimli bağlantılar, Sonlu elemanlar metodu, Composite plates, Progressive failure analysis, Pinned joints, Finite element method
Kaynak
Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi
WoS Q Değeri
Scopus Q Değeri
Cilt
3
Sayı
2
Künye
Turan, K. ve Gür, M. (2012). Pim bağlantılı tabakalı kompozit levhalarda ilerlemeli hasar analizi. Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi, 3(2), 91-99.
