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Ari Wahjudi
Universitas Brawijaya
Mechanical Engineering

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Distribusi dan Interaksi Tegangan Sisa antar Lubang Setelah Proses Cold Expansion Hole Wahjudi, Ari; Purnowidodo, Anindito; P, Andika H
Jurnal Rekayasa Mesin Vol 3, No 3 (2012)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

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Abstract

It is well known that the main cause of a failure of structure is initiated by cracks on a member. A crack may originate easily in a region with high stress concentration. Because in the rivet and the bolt joining method are usual with number of holes, and to reduce the stress concentration, the compressive residual stress is introduced in the region near by the hole. The cold expansion hole technique is used to developed compressive residual on the vicinity of the edge hole. The present study was carried out by the computer simulation based on finite element method to investigate the distribution and interaction residual stress in the region between holes related to the cold expansion hole. The result of the study suggests that the distance between holes influence the state of residual stress and its magnitude. These cause by the deformed material between holes interact each other.Keywords: residual stress distribution, stress interaction, region between holes
Hubungan Diameter Pasak, Lubang Sambungan Dan Ketebalan Plat Terhadap Distribusi Tegangan Sisa Wahjudi, Ari; Purnowidodo, Anindito; Pambudi, Wijil
Rekayasa Mesin Vol 2, No 3 (2011)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

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Abstract

The discontinuities on the structures or members are often to be encountered such as, rivet and bolt holes as well as notches. These discontinuities are agents for stress raiser and itcan initiate cracks in the vicinity of holes or in the notch roots. It is well known that most of the fatigue failure is caused by cracks growth initiated from the discontinuities. To reduce possibilitythe initiation of crack in those stress raisers, the compressive residual stress, in general, is imposed to the region in which the stress concentrates. In the present study, using expansionhole technique carried out by aid of computer simulation, the effect of mandrel diameter and thickness of the blank to the residual stress in the vicinity of the hole is investigated. The result shows that the magnitude of the residual stress in the vicinity of the hole varies depending onthe magnitude of the expansion and the thickness of blank. In addition, in the certain distancefrom the hole, the tensile residual stress develops, hence, it may endanger a component because it causes the crack growth rate increase, as consequent, the life time of a componentis shorter.Keyword: mandrell diameter, hole diameter, thickness, residual stress distribution
Analisa Kegagalan pada Spindle Mesin Batch Centrifugal Purnowidodo, Anindito; Wahjudi, Ari; Prawira, Riza
Jurnal Rekayasa Mesin Vol 2, No 1 (2011)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

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Abstract

Failure analysis was conducted on the failure shaft of batch centrifugal. In the analysis the stress analysis was used to know the stress distribution, and in conjuction with stress analysis the life time of the component can be estimated. In addition, the fractography anlaysis together with mechanical properties test were carried out to understand the mechanism of the failure. With respect to the result of analysis shows that the failure was caused by fatigue crack initated on the surface of shaft due to the inhomogeneus mechanical properties, in this case, the hardness is lower than that on sub surface of the shaft. Besides that, the stress concentration was found take place on the surface of shaft on which the crack was initated. Further, it was known that during machining process, the material of shaft was heated on elevated temperature on the surface to ease the process. The heating reduced the hardness as well as the strength of the material.Keywords : Failure, Fatigue, Crack.
PENGARUH MODE GETAR DAN ASPEK RASIO TERHADAP DISTRIBUSI TEGANGAN PADA FIBER METAL LAMINATES Khairul Anam; Anindito Purnowidodo; Tamara F. Utama; Djarot B. Darmadi; Ari Wahjudi; Agung Sugeng Widodo
Jurnal Rekayasa Mesin Vol. 13 No. 2 (2022)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v13i2.817

Abstract

Fiber metal laminates (FMLs) are widely used in various fields such as automotive and aerospace due to their high stiffness and strength-to-weight ratios. Moreover, they also have high fatigue resistance. In some applications such as aircraft structures, it is crucial to do dynamic analysis of the FMLs structure. FMLs compose of aluminium and fiberglass reinforced polymers (FRPs) are used in this study. The aim of this study is to investigate the effect of shape mode and aspect ratio on the stress distribution of FML by using finite element analysis software. Ten initial mode shapes and the aspect ratio of 1:1.5, 1:2, and 1:2.5 are used as the environmental conditions of the FMLs. The results indicate that the mode shape will change the stress distribution and the maximum stress position. Besides, the results have shown that a wider FMLs plate will increase the maximum stress and deformation. The maximum to minimum stress distribution occurs on the outer aluminium surface, the inner aluminium surface, and the FRPs surface, respectively.
Co-Authors Agung Sugeng Widodo Andika H P Anindito Purnowidodo Djarot B. Darmadi Khairul Anam Riza Prawira Tamara F. Utama Wijil Pambudi