- Email: [email protected]
Computer Programs
CHAPTER 11
Computer Programs Contents 11.1 Introduction 11.2 Mathematical Solvers 11.2.1 Introduction 11.2.2 Procedure for Downloading the Required Files 11.3 Crack Propagation Programs References
147 147 147 148 149 150
11.1 INTRODUCTION Computer programs (or computer codes) are the main tools of the modern engineering design process. There are thousands of programs, which have been developed during the last decades for use in design establishments and R&D institutes. Many of them were developed in academic institutes for a certain use, but these are generally undocumented and unsupported. On the other hand, commercially available codes are well supported, debugged, and updated. A few of them are listed and reviewed in this chapter, not including those that are outside the scope of this book. Therefore, finite element codes, used extensively in the design process, are not included here. The most used finite elements programs (not reviewed here) are the NASTRANR, ANSYSR, ADINAR, ABAQUSR, and SESAMR. These were reviewed in Ref. [11.1]. Probabilistic analysis programs were reviewed in Ref. [11.1] and in Section 3.4.5 of this book, and therefore, will not be repeated here. In this chapter, only programs that are mathematical solvers and crack propagation codes will be listed and reviewed.
11.2 MATHEMATICAL SOLVERS 11.2.1 Introduction When mathematical expressions are created, they can be solved using one of the many mathematical solvers that exist in the market. Most of these programs allow the user to solve the numerical values of mathematical Stochastic Crack Propagation ISBN 978-0-12-814191-5 http://dx.doi.org/10.1016/B978-0-12-814191-5.00011-5
© 2018 Elsevier Inc. All rights reserved.
147
148
Stochastic Crack Propagation
expressions, and to program the user’s own programs inside the envelope of these codes. The mathematical numerical solutions performed in this book use two programs, MATLABR and TKTool Kit SolverR. The well-known MATLAB [11.2] is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numerical computations. Using MATLAB, technical computing problems can be solved faster than with traditional programming languages, such as C, Cþþ, and FORTRAN. Add-on toolboxes (collection of special-purpose MATLAB functions, available separately) extend the MATLAB environment to solve particular classes of problems in these application areas. There are a lot of additional toolkits (i.e., symbolic mathematics), which make it possible to evaluate analytically very complex mathematical expressions. The leasing fee of this program is relatively high and depends on the leased content. Standard use of MATLAB requires a text file, called M-file, which should be copied into the leased program line by line. A listing of the M-files used in different chapters of this book is given in the Appendix (see also Section 11.2.2). TK Solver from UTS (United Technical Systems) [11.3] is one of the longest standing mathematical equation solvers on the market today. TK Solver readily solves simultaneous equations using iteration to significantly reduce computation and design hours. The user does not need to decide what variables will be inputs and which ones will be outputs when creating a mathematical model. This unique capability eliminates tedious “busy works” allowing the user to accomplish more in less time. The user can program his internal function within the TK Solver. There is an academic and student version, for a reasonable fee. Standard use of the program requires a file with extension .tkw, which is supplied in the Appendix and can be downloaded by the procedure described in Section 11.2.2. For clarity, the variables sheet and the rule sheet of these files are listed in the Appendix, although the computation is made by calling the required file (filename.tkw) to the leased program.
11.2.2 Procedure for Downloading the Required Files Downloading the required files is done for each file separately, in one of two possible ways: Enter the site http://crackprop.weebly.com, enter “downloads,” and select the required file. To save the file on your device, right click the
Computer Programs
149
“Download file” link and select “Save target as.” Save it to a folder of your selection. MATLAB files are text files (filename.docx) and should be pasted into the MATLAB window. TK Solver files (filename.tkw) should be inserted into the TK models folder. Alternatively, if there are problems with the previous site: Copy the following link and insert it to the Google Search Toolbar (not to the URL search): https://www.dropbox.com/sh/j7fy1y3qyx7gs76/AAAilmtv_I2Fwq0 QUWaB4qnya?dl¼0. By pressing Google “Search” you will get a list of the required files. When hovering with the mouse over the filename, a small box will be open to the left side. Check it. Then, right click on the filename and select “save target as.” This will download the file to a folder, which you decided in advance. Now you can use the file according to your wishes. Before going to the next file, uncheck the last one. If there are any problems with these sites, contact the author at [email protected].
11.3 CRACK PROPAGATION PROGRAMS For computations of crack-growth and other fracture mechanics problems, the most applied program is the NASGROR. NASGRO [11.4] is a program developed by NASA Johnson center in the 1980s. The first version NASA/FLAGRO was completed in 1986. The program was distributed by COSMIC since 1990 and was also included in the European Space Agency (ESA) crack propagation program ESACRACK. Currently, the program is maintained, updated, and distributed by the Southwest Research Institute (SwRI) in San Antonio TX. NASGRO is an envelope program, which contains internal programs for fracture mechanics principles (NASFLA), critical crack size (NASCCS), stress intensity factors (NASSIF), glasslike material behavior (NASGLS), boundary elements for 2D geometries (NASBEM), and material properties bank (NASMAT). An international consortium of users was founded, where each member contributes from their experience, to the program. A demonstration version of NASGRO 4.0 can be downloaded from the website, a version, which is limited to two geometries and one material. Material properties for hundreds of materials and heat treatments can be viewed in this demo. A very efficient computer code for the determination of 3D crack propagation was developed in the Center for Aerospace Research and
150
Stochastic Crack Propagation
Education (CARE), in the Department of Mechanical and Aerospace Engineering at the University of California at Irvine (UCI), under the direction of Prof. S.N. Atluri and his students. This program, named AGYLE, is based on a combination of finite elements and boundary elements. The program is not yet commercially available. Details can be obtained from Prof. Atluri [11.5].
REFERENCES [11.1] G. Maymon, Structural Dynamics and Probabilistic Analyses for Engineers, Elsevier Inc., Burlington, MA, 2008. [11.2] http://www.mathworks.com/matlab/, MATLAB website. [11.3] http://www.uts.com/software.asp, UTS website. [11.4] http://www.nasgro.swri.org/, NASGRO website. [11.5] [email protected], Professor Atluri e-mail address.
Computer Programs Contents 11.1 Introduction 11.2 Mathematical Solvers 11.2.1 Introduction 11.2.2 Procedure for Downloading the Required Files 11.3 Crack Propagation Programs References
147 147 147 148 149 150
11.1 INTRODUCTION Computer programs (or computer codes) are the main tools of the modern engineering design process. There are thousands of programs, which have been developed during the last decades for use in design establishments and R&D institutes. Many of them were developed in academic institutes for a certain use, but these are generally undocumented and unsupported. On the other hand, commercially available codes are well supported, debugged, and updated. A few of them are listed and reviewed in this chapter, not including those that are outside the scope of this book. Therefore, finite element codes, used extensively in the design process, are not included here. The most used finite elements programs (not reviewed here) are the NASTRANR, ANSYSR, ADINAR, ABAQUSR, and SESAMR. These were reviewed in Ref. [11.1]. Probabilistic analysis programs were reviewed in Ref. [11.1] and in Section 3.4.5 of this book, and therefore, will not be repeated here. In this chapter, only programs that are mathematical solvers and crack propagation codes will be listed and reviewed.
11.2 MATHEMATICAL SOLVERS 11.2.1 Introduction When mathematical expressions are created, they can be solved using one of the many mathematical solvers that exist in the market. Most of these programs allow the user to solve the numerical values of mathematical Stochastic Crack Propagation ISBN 978-0-12-814191-5 http://dx.doi.org/10.1016/B978-0-12-814191-5.00011-5
© 2018 Elsevier Inc. All rights reserved.
147
148
Stochastic Crack Propagation
expressions, and to program the user’s own programs inside the envelope of these codes. The mathematical numerical solutions performed in this book use two programs, MATLABR and TKTool Kit SolverR. The well-known MATLAB [11.2] is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numerical computations. Using MATLAB, technical computing problems can be solved faster than with traditional programming languages, such as C, Cþþ, and FORTRAN. Add-on toolboxes (collection of special-purpose MATLAB functions, available separately) extend the MATLAB environment to solve particular classes of problems in these application areas. There are a lot of additional toolkits (i.e., symbolic mathematics), which make it possible to evaluate analytically very complex mathematical expressions. The leasing fee of this program is relatively high and depends on the leased content. Standard use of MATLAB requires a text file, called M-file, which should be copied into the leased program line by line. A listing of the M-files used in different chapters of this book is given in the Appendix (see also Section 11.2.2). TK Solver from UTS (United Technical Systems) [11.3] is one of the longest standing mathematical equation solvers on the market today. TK Solver readily solves simultaneous equations using iteration to significantly reduce computation and design hours. The user does not need to decide what variables will be inputs and which ones will be outputs when creating a mathematical model. This unique capability eliminates tedious “busy works” allowing the user to accomplish more in less time. The user can program his internal function within the TK Solver. There is an academic and student version, for a reasonable fee. Standard use of the program requires a file with extension .tkw, which is supplied in the Appendix and can be downloaded by the procedure described in Section 11.2.2. For clarity, the variables sheet and the rule sheet of these files are listed in the Appendix, although the computation is made by calling the required file (filename.tkw) to the leased program.
11.2.2 Procedure for Downloading the Required Files Downloading the required files is done for each file separately, in one of two possible ways: Enter the site http://crackprop.weebly.com, enter “downloads,” and select the required file. To save the file on your device, right click the
Computer Programs
149
“Download file” link and select “Save target as.” Save it to a folder of your selection. MATLAB files are text files (filename.docx) and should be pasted into the MATLAB window. TK Solver files (filename.tkw) should be inserted into the TK models folder. Alternatively, if there are problems with the previous site: Copy the following link and insert it to the Google Search Toolbar (not to the URL search): https://www.dropbox.com/sh/j7fy1y3qyx7gs76/AAAilmtv_I2Fwq0 QUWaB4qnya?dl¼0. By pressing Google “Search” you will get a list of the required files. When hovering with the mouse over the filename, a small box will be open to the left side. Check it. Then, right click on the filename and select “save target as.” This will download the file to a folder, which you decided in advance. Now you can use the file according to your wishes. Before going to the next file, uncheck the last one. If there are any problems with these sites, contact the author at [email protected].
11.3 CRACK PROPAGATION PROGRAMS For computations of crack-growth and other fracture mechanics problems, the most applied program is the NASGROR. NASGRO [11.4] is a program developed by NASA Johnson center in the 1980s. The first version NASA/FLAGRO was completed in 1986. The program was distributed by COSMIC since 1990 and was also included in the European Space Agency (ESA) crack propagation program ESACRACK. Currently, the program is maintained, updated, and distributed by the Southwest Research Institute (SwRI) in San Antonio TX. NASGRO is an envelope program, which contains internal programs for fracture mechanics principles (NASFLA), critical crack size (NASCCS), stress intensity factors (NASSIF), glasslike material behavior (NASGLS), boundary elements for 2D geometries (NASBEM), and material properties bank (NASMAT). An international consortium of users was founded, where each member contributes from their experience, to the program. A demonstration version of NASGRO 4.0 can be downloaded from the website, a version, which is limited to two geometries and one material. Material properties for hundreds of materials and heat treatments can be viewed in this demo. A very efficient computer code for the determination of 3D crack propagation was developed in the Center for Aerospace Research and
150
Stochastic Crack Propagation
Education (CARE), in the Department of Mechanical and Aerospace Engineering at the University of California at Irvine (UCI), under the direction of Prof. S.N. Atluri and his students. This program, named AGYLE, is based on a combination of finite elements and boundary elements. The program is not yet commercially available. Details can be obtained from Prof. Atluri [11.5].
REFERENCES [11.1] G. Maymon, Structural Dynamics and Probabilistic Analyses for Engineers, Elsevier Inc., Burlington, MA, 2008. [11.2] http://www.mathworks.com/matlab/, MATLAB website. [11.3] http://www.uts.com/software.asp, UTS website. [11.4] http://www.nasgro.swri.org/, NASGRO website. [11.5] [email protected], Professor Atluri e-mail address.