scholarly journals KAJI NUMERIK PENCEGAHAN PERTUMBUHAN RETAK DENGAN MENGGUNAKAN METODE MODIFIKASI BENTUK STOP-DRILLED HOLE (SDH)

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
Yudi Dwianda ◽  
Hendery Dahlan ◽  
Meifal Rusli
Keyword(s):  
Stress Concentration ◽  
Crack Propagation ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
High Stress ◽  
Fatigue Cracking ◽  
Stress Concentrations ◽  
High Stress Concentration ◽  
Hole Radius ◽  
Hole Model

ABSTRAK Salah satu mekanisme kegagalan yang utama dalam aplikasi teknik atau komponen mesin adalah penjalaran retak kelelahan. Penjalaran retak ini biasanya dimulai dari titik-titik pada daerah yang mengalami konsentrasi tegangan yang tinggi. Oleh karena itu salah satu metode untuk menghambat penjalaran retak adalah  mereduksi konsentrasi tegangan dimana salah satu metode yang digunakan adalah pemberian lubang di ujung retak atau dikenal dengan stop-drilled hole (SDH). Pada penelitian ini akan dikembangkan modifikasi bentuk model SDH. Pada dasarnya model yang dikembangkan ini adalah merubah bentuk pada sisi lubang agar tidak berbentuk lengkungan sehingga  konsentrasi tegangan menurun di daerah tersebut. Pemodelan lubang yang dikembangkan pada peneltian ini adalah penggambungan dua lubang dan tiga lubang pada ujung retak. Pada penelitian ini akan dilakukan penghitungan faktor konsentrasi tegangan untuk variasi jari-jari lubang yang diberikan. Dari penelitian yang telah dilakukan dapat disimpulkan bahwa pemberian dua lubang dan tiga lubang pada ujung cetak tersebut dapat mereduksi faktor konsentrasi tegangan dengan signifikan, nilai faktor konsentrasi tegangan antara dua lubang dan tiga lubang tidak berbeda signifikan terutama dengan meningkatnya nilai jari-jari lubang. Sementara itu, faktor konsentrasi tegangan tetinggi terjadi pada daerah perubahan geometri pada lubang untuk pemberian dua atau tiga lubang, akan tetapi faktor konsentrasi tegangannya masih cukup rendah jika dibandingkan dengan pemberian satu lubang. Kata Kunci : Konsentrasi Tegangan, Penjalaran Retak, Stop-Drilled Hole (SDH)   ABSTRACT One of the major failure mechanisms in engineering applications or machine components is the propagation of fatigue cracking. The spreading of these cracks usually are started from the points on the regions that are  experiencing high stress concentrations. Therefore, one of the method to inhibit this crack propagation is reducing the stress concentration in which one of the used methods  is the provision of a hole at the end of a crack or known as a stop-drilled hole (SDH). In this research will be developed  a modification form of SDH model. Basically the developed model is changing the shape on the hole side so there are not forming of the curve so that the stress concentration decreases in this area. The developed hole model in this research is the binding of two holes and three holes at the crack tip. This research will be calculated the stress concentration factor for variation of given hole radius. From the research that has been done, it can be concluded that the two holes and three holes on the tip of the crack can reduce the stress concentration factor significantly. Moreover,  the value of the stress concentration factor between two holes and three holes is not significantly different, especially with the increment of the hole radius. Meanwhile, the high stress concentration factor occured in the geometrical change area of the hole for two or three holes, but the stress concentration factor is still quite low when compared to the one hole. Keywords : Stress Concentration, Crack Propagation, Stop-Drilled Hole (SDH)

Effect of Blend Radius on Stress Concentration Factor of Crossbored Holes in Thick Walled Pressure Vessels

2003 ◽  
Author(s):  
Daniel T. Peters
Keyword(s):  
Stress Concentration ◽  
Detailed Analysis ◽  
Computer Technology ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Pressure Vessels ◽  
Stress Concentrations ◽  
The Past ◽  
Recent Developments ◽  
Fea Analysis

Many studies have been performed on the effect of stress concentration factor in thick walled cylinders caused by holes drilled to the wall perpendicular to the vessel ID, commonly called crossbores. Recent developments in FEA analysis and computer technology have allowed detailed analysis in their effect on the stresses in pressure vessels. This allows the reevaluation of many theories developed in the past. The following is a study of how applying a blend radius to the inside intersection of a vessel bore and a crossbore affects the stresses in vicinity of the hole and the stress concentrations developed near the hole.

Finite Element Analysis on Stress Concentration of Well Casing With Corrosion Pits

2010 ◽  
Author(s):  
Jing Zhang ◽  
Jianchun Fan ◽  
Laibin Zhang ◽  
Dong Wen ◽  
Yumei Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Spherical Cavity ◽  
High Stress ◽  
Orifice Diameter ◽  
Element Analysis ◽  
Corrosion Pits

Corrosion-induced pits will disturb the original stress distribution of casing and appear local high stress area. Through 3-D finite element analysis on casing with spherical and cylindrical corrosion cavity, the stress concentration degree and the influences of cavity shape, size and orifice diameter on stress concentration factor are determined and analyzed. The results show that the depth and shape of corrosion cavities are major factors impacting the stress concentration factor. For the casing with corrosion pits, the smaller orifice diameter, the more obvious influence of hemisphere effect on stress concentration factor. With the transition from shallow-spherical cavity to exact hemispherical cavity or from exact hemispherical cavity to deep-spherical cavity or from exact hemispherical cavity to cylindrical cavity, the changes of stress concentration factor show different characteristics.

Statistical Approach of Stress Concentration Factor (SCF) Within Pipeline Girth Welds

2014 ◽  
Author(s):  
Pierre-Louis Auvret ◽  
Antonio Carlucci ◽  
Jun Li ◽  
Kamel MCirdi
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Material Behavior ◽  
Stress Concentrations ◽  
Alignment Procedure ◽  
Fabrication Tolerances ◽  
Girth Welds ◽  
Pipe Size

Engineering design must take care of local peaks within stress field, in order to provide relevant forecast of material behavior. Within pipeline girth welds, pipe misalignment is an ordinary cause of significant stress concentrations. The matching of pipe ends depends of the quality of alignment procedure but it is also much influenced by pipe fabrication tolerances. In general, misalignment is estimated considering the maximal and minimal values of each pipe size according to pipe fabrication tolerances. But, in practice, the probability to get a such case is very low. This paper describes how to improve the calculation of stress concentration factor (SCF) through a statistical analysis of pipe dimensions. The use of actual pipe measurements is not necessary even if it provides better SCF estimation. Indeed the distribution of pipe size can be estimated through the fabrication tolerances which require acceptable capacities of the manufacturing system.

Effect of notch sensitivity on the mechanical properties of HA/PEEK functional gradient biocomposites

2016 ◽  
Vol 36 (9) ◽  
pp. 933-941 ◽  
Author(s):  
Pan Yusong ◽  
Chen Yan ◽  
Shen Qianqian ◽  
Pan Chengling
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Orthopedic Implants ◽  
Fracture Morphology ◽  
Notch Sensitivity ◽  
Stress Concentrations ◽  
Stress Strain ◽  
Functional Gradient ◽  
Strain Behavior

Abstract Biomaterials used as loading-bearing orthopedic implants usually require various excellent properties such as mechanical, bioactive and bio-tribological performances. Moreover, all of the orthopedic applications feature stress concentrations (notch sensitivity) in their design. In the present work, hydroxyapatite-reinforced polyetheretherketone functional gradient biocomposites (HA/PEEK FGBm) were successfully prepared by the layer stacking method combined with hot pressing molding technology. The effects of notch geometry on the stress-strain behavior of HA/PEEK FGBm were evaluated. The fracture morphology was investigated by scanning electron microscopy (SEM). The study of the stress-strain behavior indicated that the tensile and flexural stresses of HA/PEEK FGBm linearly increased with increasing strain under all the notch sensitivities. The fracture strain of the biocomposites decreased with increasing stress concentration factor and total HA content in the functional biocomposites. Moreover, the tensile and flexural strengths of HA/PEEK FGBm were lower than those of homogeneous HA/PEEK biocomposites. The SEM observation of the fracture micro-morphology showed that the fracture mechanism of HA/PEEK FGBm was gradually controlled by the brittle fracture process. Furthermore, both the tensile and the flexural strengths of HA/PEEK FGBm decreased with the increase in stress concentration factor and total HA content in the biocomposites.

scholarly journals The effect of non-metallic inclusion size and orientation on tensile properties of stainless steel (simulation and experiment)

10.30544/471 ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 43-55
Author(s):  
Peyman Ahmadian ◽  
Mahdi Taghizadeh
Keyword(s):  
Stress Concentration ◽  
Tensile Properties ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
High Stress ◽  
Metallic Matrix ◽  
Inclusion Size ◽  
Metallic Inclusion ◽  
Element Analysis ◽  
9Ni Steel

In this study, the effect of non-metallic inclusions (NMIs) on tensile behavior of titanium stabilized Fe-20Cr-9Ni steel was investigated. The size of NMIs was decreased via the electro-slag remelting (ESR) process. JK-inclusion rating method revealed that the studied steel consisted of D-type (square-shaped) inclusions. According to energy dispersive spectroscopy, it was determined that the appeared inclusions in the matrix of the titanium stabilized Fe-20Cr-9Ni steel is predominantly titanium nitride (TiN). As a result of the ESR process, excellent improvement in the tensile properties of the studied steel was observed. Subsequently, the effect of inclusion size (d = 5, 10, 25, 50 µm) and orientation (α = 0, 45°) on stress concentration factor around the non-metallic inclusion and metallic matrix was simulated. The result of finite element analysis indicated that, for both square (α = 0 °) and rhombus (α = 45°) shape inclusions, increasing inclusion size has resulted in high-stress concentration factor during plastic deformation. On the other hands, generated Mises stress field around the non-metallic inclusion presented that, for the same inclusion size, rhombus (α = 45°) shape inclusion is more susceptible to homogenous deformation in comparison with square (α = 0°) one.

scholarly journals New Methods for Stress Concentration Factor Calculation in Butt Welded Joints: A Comparative Study

2020 ◽  
Author(s):  
Miroslav Randic ◽  
Duško Pavletić ◽  
Marko Fabić
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Welded Joints ◽  
Concentration Factor ◽  
Computer Software ◽  
Base Material ◽  
Geometric Parameters ◽  
Stress Concentrations ◽  
Weld Toe ◽  
Toe Angle

Abstract Surface cracks in butt-welded joints usually occur in places with increased stress concentrations. The stress concentration factor (SCF) can be calculated using an empirical equation, with five geometric parameters of a butt-welded joint (thickness of the base material, toe radius, weld toe angle, weld width, and reinforcement height). However, in anindustrial environment, it is impractical and sometimes even impossible to measure all five geometric parameters with sufficient accuracy. In this study, eight experiments on butt-welded joints were performed. All samples were scanned with a 3D scanner, and the geometric sizes of the welded joints were measured using computer software. A modified empirical expression proposed by Ushirokawa and Nakayama was used to calculate the SCF; the expression was adjusted in such a way that the SCF was calculated by knowing only the toe radius. In addition, four new expressions were proposed for the calculation of the SCF by knowing the toe radius in relation to the weld toe angle; the expressions were then compared and analysed. Additionally, the values of the stress concentrations in the butt-welded joints were obtained using afinite element method (FEM). The SCFs calculated using the four methods were compared and further discussed. Our data suggested a new accurate and straightforward approach for calculating the SCF by knowing only the weld toe radius.

Packaging Materials for Flip Chip and WLP: Underfill Design Using FEM for FC-BGA, FC-CSP, and Moving Towards 2.5/3D.

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 001295-001327
Author(s):  
Brian Schmaltz ◽  
Yukinari Abe ◽  
Kazuyuki Kohara
Keyword(s):  
Stress Concentration ◽  
Dielectric Layer ◽  
Flip Chip ◽  
Failure Modes ◽  
High Stress ◽  
Lead Free ◽  
Typical Result ◽  
Stress Concentrations ◽  
High Stress Concentration ◽  
Technology Nodes

As technology nodes progress to 16/14nm and beyond underfill materials are presented with the significantly challenging task of maintaining bump protection while ensuring low warpage for ultra low-K dielectric (ULK/ELK) integrity. This challenge is further complicated by the trend toward RoHS compliancy (lead-free) and an ever increasing die size (beyond 25x25mm). Through extensive research and testing, several specifically formulated underfill materials were determined acceptable solutions for these complex issues. As technology nodes progress to smaller processes high stress concentrations are seen at the dielectric layer during thermal cycling. This stress is a typical result of a high glass transition temperature (Tg) / high strength material that often leads delamination or a cracking failure mode of the thin dielectric layer. Too low of a Tg presents a high stress concentration on the bumps which once again constitutes failure, this time, however, the crack is typically seen at the bump location. This high stress concentration seen at the bumps is more significant when lead free bumps are considered due to their inherent fragile nature. Underfill materials must now be specifically optimized for variable package conditions to solve these failure modes for a large variation of package designs. Desired material properties must be quickly calculated using finite element methods. This paper will discuss solutions to typical failure modes currently seen in reliability testing of present and future technologies.

Notcheffect on J and Amplification of Anisotropic Stress Concentration Factor in a Laminated Plate Subjected to Tensile Load

2015 ◽  
Vol 1105 ◽  
pp. 381-385
Author(s):  
Djamel Ouinas ◽  
Bel Abbès Bachir Bouiadjra ◽  
A. Albedah ◽  
Mohamed Sahnoun
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Fibre Orientation ◽  
Notch Root ◽  
Tensile Load ◽  
Homogeneous Material ◽  
Laminated Plate ◽  
Stress Concentrations ◽  
Anisotropic Stress

Several analytical, numerical and experimental techniques are available to study the stress concentration around the notches. The stress distribution in a rectangular composite laminated plate with a central notch was studied using the finite element method. The objective of this study is to analyze the fibre orientation effect on the variation of stress concentrations at the notch root and the J-integral at the crack-tip emanating from this notch in a plate subjected to tensile loading. The results show that the anisotropic stress concentration factor can be higher or lower than that of a homogeneous material. The area of maximum normal and tangential stresses could shift with fibre orientation with respect to the loading axis. The interaction effect between a crack located on the ligament of the plate and the circular notch of radius is considered.The results indicate that fold sequence influences appreciably the acceleration or the retardation of the crack propagation.

scholarly journals Stress concentrations at an oblique hole in a thick plate

2000 ◽  
Vol 35 (2) ◽  
pp. 143-147 ◽  
Author(s):  
P Stanley ◽  
A G Starr
Keyword(s):  
Stress Concentration ◽  
Flat Plate ◽  
Uniaxial Tension ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Thick Plate ◽  
Empirical Equation ◽  
Elastic Stress ◽  
Cylindrical Hole ◽  
Stress Concentrations

An empirical equation has been obtained for the elastic stress concentration factor at an isolated oblique circular-cylindrical hole in a thick flat plate subjected to a uniform, arbitrarily oriented uniaxial tension. The equation is presented and its development is outlined in this note.

Simplified Fatigue Design Assessment (FDA) Procedure for Slots/Cut-Outs Based on a Stress Concentration Factor (SCF) Approach

2010 ◽  
Author(s):  
T. Sia ◽  
R. Jago ◽  
J. Tong ◽  
S. M. Zhang
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Fatigue Cracking ◽  
Fatigue Performance ◽  
Fe Model ◽  
Structural Detail ◽  
Design Assessment ◽  
Fatigue Design ◽  
Longitudinal Stiffeners

The Fatigue Design Assessment (FDA) procedure is a part of ShipRight design, construction and lifetime ship care procedures developed by Lloyds Register. The work presented in this paper is on the application of a Stress Concentration Factor (SCF) approach to the FDA procedure to develop an effective and user friendly tool for the assessment of fatigue performance of cut-outs in transverse web frames for longitudinal stiffeners. Investigation of hull damage statistics has identified that fatigue cracking in way of cut-outs and end brackets of longitudinal stiffeners affects a reasonable proportion of ships in service. This can become an ongoing ‘through life’ maintenance issue as defects can re-occur if the design of the structural detail has insufficient fatigue performance. A spectral fatigue assessment of this structural detail has traditionally been based on localised mesh refinement applied to a global finite element (FE) model and hydrodynamic calculated using first principle methods. These traditional methods are time, resource and labour intensive processes and therefore limited in its application. The SCF approach developed offers a faster and simpler method for the determination of hotspot stresses for standardised cut-out details.

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