LAPORAN HASIL PENELITIAN FUNDAMENTAL TAHUN ANGGARAN 2010

Transkripsi

1 TEKNIK MESIN LAPORAN HASIL PENELITIAN FUNDAMENTAL TAHUN ANGGARAN 2010 Hubungan Kontraksi Lateral, Ketebalan Material dan Kondisi Siklus Beban Terhadap Kondisi Tegangan Sisa di Depan Ujung Retak Oleh: Dr. Anindito P, ST., M.Eng. Ir. Ari Wahjudi, MT. Ir.Erwin Sulistiyo, MT. Dibiayai Oleh Direktorat Jenderal Pendidikan Tinggi, Kementerian Pendidikan Nasional, melalui DIPA Universitas Brawijaya berdasarkan SK Rektor Nomor: 039/SK/2010, tanggal 17 Februari Universitas Brawijaya Nopember 2010

2

3 RINGKASAN Hubungan Kontraksi Lateral, Ketebalan Material dan kondisi Siklus Beban Terhadap Kondisi Tegangan Sisa di Depan Ujung Retak Oleh : Dr. Anindito P, ST., M.Eng. Ir. Ari Wahjudi, MT. Ir.Erwin Sulistiyo, MT Dalam penelitian ini simulasi numerik berbasis metode elemen hingga digunakan untuk meneliti sejauh mana pengaruh kontraksi lateral terhadap tegangan sisa yang terbentuk di ujung retak, dan ini akan dilakukan pada center cracked specimen dengan variasi ketebalan dan kondisi siklus beban overload. Ketebalan menjadi fokus studi ini juga, karena ketebalan mempengaruhi perilaku dan umur rambat retak. Pada studi ini, untuk mensimulasikan hubungan kontraksi lateral, ketebalan dan kondisi tegangan sisa di daerah ujung retak atau pada daerah overloadaffected-zone, etode finite element digunakan dengan bantuan software ANSYS. Jenis specimen yang digunakan dalam penelitian ini adalah type centered crack Dari simulasi ini dapat disimpulkan bahwa :Pada Stress Ratio R = 0, pada saat akhir siklus tegangan sisa yang terbentuk adalah tegangan sisa tekan dan untuk R = -1.5, yang terbentuk adalah tegangan sisa tarik. Besar tegangan sisa yang terjadi pada akhir siklus dipengaruhi oleh ketebalan dari model specimen. Besar dan kondisi tegangan sisa dipengaruhi oleh kontrasi material searah overload dan juga kontraksi lateral. Pada stress ratio R = -1.5, tidak ditemukan bulging atau tonjolan kearah lateral dan tegangan sisa tarik yang terjadi karena adanya penuruna regangan plastis.

4 SUMMARY The Relations of Lateral contraction, Thickness and Cycles Load Condition on Residual Stress State in the Fornt of Crack Tip By : Dr. Anindito P, ST., M.Eng. Ir. Ari Wahjudi, MT. Ir.Erwin Sulistiyo, MT The mechanism of residual stress development in front of the crack tip was investigated in association with the thickness and overload condition. The understanding of the mechanism is very important because the development of the residual stress relates to a crack growth behavior after overloading and a life time of fatigued crack. The investigation was conducted under simulation computer by aid of software based on finite element method. The result of the simulation shows that the residual stress state and the magnitude in front of thecrack tip is affected by the overload condition and the thickness of material.

5 DAFTAR PUSTAKA Bao, H. and McEvily, A. J. The Effect of Overload on the Rate of Crack Propagation under Plane Stress Conditions. Metallurgical and Materials,Vol. 26A, 1995, pp Barsom, J.M., Rofle, S.T., Fracture and Fatigue Control in Structure. Appliaction of Fracture Mechanics, ASTM,MNL41, Brooks, C.R., Choudhury A, "Failure Analysis of Engineering Materilas", Professional Engineering, Carter, Tim J., "Common Failures in Gas Turbine Blades", Engineering Failure Analysis, Vol. 12, 2005, pp Elber, W. The Significance of Fatigue Crack Closure. ASTM STP 486. American Society for Testing and Materials, Philadelphia; 1971, pp Makabe, C., McEvily, A. J., Purnowidodo, A. and Yamauchi, A. Effects of Negative Stress Ratios on Crack Propagation Behavior after an Overload. Int. J. Modern Physics. B, Vol.17, 2003, PP Makabe, C., Purnowidodo, A. and McEvily, A. J. Effects of Surface Deformation and Crack Closure on Fatigue Crack Propagation after Overloading andunderloading, Int. J. Fatigue, Vol.26, 2004, pp Makabe C., Purnowidodo, A., Miyazaki, T., and McEvily, Arthur J. Deceleration and Acceleration of Crack Propagation after an Overloading under Negative Baseline Stress Ratio, Journal of Testing and Evaluation, American Society Testing Material, Vol. 33, , McEvily, A. J. and Yang, Z. The Nature of the Two Opening Levels Following an Overload in Fatigue Crack Growth. Metallurgical Transactions, Vol.21A, 1990, pp McEvily, A. J., Ishihara, S., Mutoh, Y., On the Number of Overload-Induced Delay Cycles as Function of Thickness Int. J. Fatigue, Vol.26, 2004, pp , (A). McEvily, A.J., "Failures in Inspection Procedures: Case Studies", EngineeringFailure Analysis, Vol. 11, 2004, pp , (B). Purnowidodo, A., Choiron, M. A., Effect of Static Overload on Fatigue Crack Propagation and Fatigue Life on Engineering Materials, Proceeding, Callobaration Workshop on Energy, Environment and New Trend in Mechanical Engineering, Brawijaya University and Keio University, 2003,pp Purnowidodo, A., Makabe, C., Miyazaki, T., and McEvily, A. J., Transition Behavior of Residual Fatigue Life after Applying Overload during Fatigue Crack Growth with Constant Stress Amplitude, Pressure Vessel and Piping Codes and Standards, ASME/JSME-PVP, Vol. 480, San Diego, California USA, pp (2004). Stephens, R.I., Fatemi, A., Stephens, R.R., Fuchs, H.O., Metal Fatigue in Engineering,2001. Topper, T. H. and Lam, T. S., Derivation of Crack Closure and Effective Fatigue Crack Growth Data from Smooth Specimen Fatigue Test, Report of Fatigue Branch of the Society of Materials Science, Japan, Vol. 266, 2003, pp

6 Ward-Close, M., Blom, A. F. and Ritchie, R. O. Mechanisms Associated with Transient Fatigue Crack Growth under Variable-Amplitude Loading: AnExperimental and Numerical Study. Engineering Fracture Mechanics, Vol. 32, 1989, pp