Crack driving force prediction based on finite element analysis using standard models

2012 ◽  
Vol 44 (5) ◽  
pp. 601-609 ◽  
Author(s):  
Josip Brnic ◽  
Goran Vukelic ◽  
Goran Turkalj
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Driving Force ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Force Prediction ◽  
Standard Models

Estimation of Dynamic Mechanical Error for Evaluation of Machine Tool Structures

2012 ◽  
Vol 6 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Daisuke Kono ◽  
◽  
Sascha Weikert ◽  
Atsushi Matsubara ◽  
Kazuo Yamazaki ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Machine Tool ◽  
Driving Force ◽  
Inertial Force ◽  
Element Analysis ◽  
Simple Method ◽  
Dynamic Mechanical ◽  
Machine Tool Structures ◽  
Multi Body

Dynamic motion errors of machine tools consist of errors in the mechanical system and the servo system. In this study, a simple method to estimate the dynamic mechanical error is proposed to evaluate machine tool structures. The dynamic mechanical error in the low frequency range is estimated from the static deformation due to the driving force, the counter force, and the inertial force. The error in a high-precision machine tool is estimated for comparison with measurements. Two calculation tools, finite element analysis and rigid multi-body simulation, are used for the estimation. Measured dynamic mechanical errors can be correctly estimated by the proposed method using finite element analysis. The tilt of driven bodies is the major reason for dynamic mechanical errors. When the reduction factor representing the structural deformation is properly determined, the rigid multi-body simulation is also an effective tool. Use of the proposed method for modification planning is demonstrated. Stiffness enhancement of the saddle was an effective modification candidate to reduce the dynamic mechanical error. If the error should be reduced to sub-micrometer level, the location of components should be modified because the Abbe offset and the offset of the driving force from the inertial force must be shortened.

scholarly journals A Finite Element Analysis of a Crack Penetrating or Deflecting into an Interface in a Thin Laminate

2006 ◽  
Vol 312 ◽  
pp. 173-178 ◽  
Author(s):  
Sharon Kao-Walter ◽  
Per Ståhle ◽  
Shao Hua Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Driving Force ◽  
Crack Tip ◽  
Element Analysis ◽  
Linear Fracture ◽  
Finite Element Calculations ◽  
Straight Ahead

The crack tip driving force of a crack growing from a pre-crack that is perpendicular to and terminating at an interface between two materials is investigated using a linear fracture mechanics theory. The analysis is performed both for a crack penetrating the interface, growing straight ahead, and for a crack deflecting into the interface. The results from finite element calculations are compared with asymptotic solutions for infinitesimally small crack extensions. The solution is found to be accurate even for fairly large amounts of crack growth. Further, by comparing the crack tip driving force of the deflected crack with that of the penetrating crack, it is shown how to control the path of the crack by choosing the adhesion of the interface relative to the material toughness.

Issues in Welding Residual Stress Model in Fitness for Service Assessment of Crack-Like Defect in Weld Area

2015 ◽  
Author(s):  
Jeong K. (J. K.) Hong ◽  
Richard P. Brodzinski ◽  
Pedro M. Vargas ◽  
H. Chong Rhee ◽  
K-John Young ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Driving Force ◽  
Welding Residual Stress ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Defect Assessment ◽  
Technical Issues ◽  
Weld Area ◽  
Force Calculation

Current Industry Code and Standard (ICS) Fitness for Service Assessment (FFSA) procedures for crack-like defect in weld area tend to impose high level of conservatism. In addition to the necessity for using conservative Welding Residual Stress (WRS) model due to the uncertainty inherent in the WRS estimation, using the original WRS regardless of crack depth in the crack driving force calculation, like the applied operating load, is the primary reason for this solution conservatism. In addition, current ICS weld area defect assessment procedures involve ambiguities in boundary condition effects on WRS models, as well as in the fracture mode of weld area crack being treated in the context of opening mode only, even though there is no weld area geometric symmetry essential for precluding fracture modes other than mode I. To clarify these technical issues in the ICS FFSA practices rigorous numerical simulation analyses of welding process and crack growth following joint fabrication have been performed, using the finite element analysis procedure. A crack driving force calculation procedure for weld area cracks, which was developed to quantify the crack extension effects on WRS for growing crack, was used for the finite element crack growth simulation analyses. The rigorous finite element analysis results for boundary condition effects on WRS, the fracture mode of weld toe crack, and crack growth effects on crack driving force parameters caused by WRS are compared with those of current ICS solutions. These comparisons demonstrate the need for an improvement of the current ICS FFSA procedures for weld area crack-like defects. The primary objective of the present paper is to motivate the industry to improve ICS FFSA procedures by clarifying these ambiguous technical issues in weld area crack-like defect assessment parameters, as well as considering crack extension effects on WRS properly in calculating the crack driving force of growing crack to reduce undue conservatism in FFSA.

Sign in / Sign up

Export Citation Format

Share Document