Z88 FEM software

Last updated
Z88
Developer(s) Frank Rieg and team
Stable release
Z88V15OS
Z88Aurora V5
Z88Arion V3 / 17 July 2017/ 1 April 2019/ 23 April 2018
Repository
Operating system Windows,
Linux, Unix,
Mac OS X
Type Finite element analysis
License Z88V15 GNU GPL
Z88Aurora V5 (Custom)
Website z88.de

Z88 is a software package for the finite element method (FEM) and topology optimization. A team led by Frank Rieg at the University of Bayreuth started development in 1985 and now the software is used by several universities, as well as small and medium-sized enterprises. Z88 is capable of calculating two and three dimensional element types with a linear approach. The software package contains several solvers and two post-processors and is available for Microsoft Windows, Mac OS X and Unix/Linux computers in 32-bit and 64-bit versions. Benchmark tests conducted in 2007 showed a performance on par with commercial software. [1]

Contents

History and functionalities

Overview

The software was developed by Frank Rieg, a professor for engineering design and CAD at the University of Bayreuth. Originally written in FORTRAN  77, the program was ported to the programming language C in the early 1990s.
There are two programs for finite element analysis:

Since 2014 two Android Apps are also available:

The product family is supported by a software for topology optimization since 2016:

Functionalities of Z88Aurora

Z88Aurora's current version contains several computation modules:

Regardless of what module was selected the finite element analysis using Z88Aurora can be divided into three areas: pre-processor, solver (processor) and post-processor.

The pre-processor builds the FE model. It is possible to either build the structure directly inside the software by using Z88Aurora's tools and using structural elements such as trusses and beams or a model can be imported from several file formats. Geometries can be imported from STEP files (*.STP), STL files in ASCII or binary format (*.STL) or Autocad files (*.DXF), while FE structure data can be imported from NASTRAN files (*.NAS), ABAQUS files (*.INP), ANSYS files (*.ANS) or COSMOS files (*.COS). Z88Aurora contains a total of 25 different element types, including 2D elements (truss, beam, plane stress elements, shaft elements, torus elements) and 3D elements (truss, beam, linear and quadratic tetrahedrons and hexahedrons). Two open source meshers (TetGen, by Dr. Hang Si (WIAS Berlin) and NETGEN, by Prof. Joachim Schöberl (TU Wien)) generate tetrahedron meshes. A tetrahedrons refiner for existing tetrahedrons meshes (linear and quadratic), a mapped mesher for superelement structures (hexahedrons, shells, etc.), a shell thickener that creates column shells from 2D shell elements and a trimming function serve to refine the model. The set management enables an easy selection of surfaces, nodes and elements to apply boundary conditions, define materials, etc. The material database contains 52 pre-defined materials and is editable and can be extended easily. Various boundary conditions such as forces, displacements, pressure and thermal conditions can be applied using the graphical user interface.

The solver computes displacements, stresses, temperatures and nodal forces depending on the selected computation module. Four numerical solvers are available for the linear finite element analysis:

Stationary thermal or thermomechanical calculations use the iterative solvers or the direct multicore solver.

Nonlinear calculations are done by applying a special iterative solver. The natural frequency simulation uses the Lanczos procedure.

The results are visualized using the post-processor. It is possible to filter results or clip the part to view only the relevant sections. Specific results can be exported to text or CSV format and the analysis function permits the display of results pertaining to a single node. Moreover, the deformed structure can be used in other applications by exporting it to an STL file.

The software comes with a Windows user interface with context-sensitive online help. Handbooks are available, demonstrating the use of Z88 and Z88Aurora, using examples.
The Freeware is available for Windows, Linux and OS X.

Functionalities of Z88Arion

Topology optimization is done by optimizing an existing structure towards a given target function by changing its topology class within a pre-defined space. By removing material in suitable places an optimal structure is created. The goal of topology optimization is the automatic creation of an optimal structure under defined applied forces and boundary conditions within the virtual product development process. [3] A draft model provides the basis. Displacements, stresses and natural frequencies and oscillations are computed via a structural analysis and will be taken into consideration by the optimization process. It is at this point that the exact model and design variables for the optimization process are defined. Not only the target function but also the boundary conditions and restrictions are defined here. The optimization problem is solved by an algorithm that iterates variations of the design variables. The result is an improved draft model, that goes through the same process until an optimal draft, the so-called design suggestion is achieved.

Depending on the goal of the topology optimization two different methods can be chosen: [4]

The OC method produces a design suggestion that features maximal stiffness in relation to a previously defined relative volume. [5] The SKO process optimizes for maximum strength. The TOSS algorithm was specially developed by the development team at the University of Bayreuth and can be understood as an advancement of the OC method. It is a hybrid process of OC and a so-called SKO method (Soft Kill Option) and uses the optimal stiff structure resulting from the OC method and uses it as a basis to create a stress-optimized design suggestion. To do so material is added in overstressed areas and removed in understressed areas. [6]

The determined design proposal is displayed in the postprocessor. For example, the user can look at different iterations and vary presentation limits. In addition, since Z88Arion V2, it is possible to smooth the resulting structure and export it as STL to ensure direct reuse of the optimized part in other programs. There is also a direct interface to Z88Aurora.

Application

Application in teaching and research

Z88 has been used to educate engineering students at the University of Bayreuth since 1998. The possibility of manual creation of the structure and the application of boundary conditions enables a simple visualization of the function of FEM software. Due to the open file sources the software can be used for research purposes in FE areas and can be modified to suit individualized needs.

Among others, Z88 is used for research and teaching at the University Ravensburg-Weingarten, [7] the University of Ioannina, [8] the Penn State University, [9] the Universidad de Buenos Aires, [10] the University of Cagliari, [11] the University of Maribor, [12] and at the Zonguldak Karaelmas Üniversitesi. [13] Additionally Z88 has been used for degree theses at the Universities of Darmstadt, Hamburg-Harburg, Munich, Karlsruhe, Bern and Beijing (among others).

Furthermore, there are two textbooks using Z88. Finite Elemente Analyse for Ingenieure: Eine leicht verständliche Einführung has sold over 6000 copies. This textbook is designed for entry-level users of finite element analysis and useas Z88 to let the user follow the examples shown in the book on his own system. The book Maschinenelemente - Funktion, Gestaltung und Berechnung by Decker (19th edition) uses practical applications with Z88 to teach the calculation of machine elements with finite element analysis.

Application in the industry

Due to the Open Source approach many applications use the Z88 solver, its plot output, etc. Among other things Z88 has been adapted into a program to calculate point concentrated and linear loads on glass panes in building construction. Routines have been implemented to determine the Young's modulus and flexural strength of wood and a sub-application has been developed to calculate pressure vessels. Examples of companies using Z88 are

The availability of the source code and thus the transparency of applied algorithms and material models make Z88 ideal as a reference software for commercial tools such as NASTRAN and ABAQUS.

Literature

Related Research Articles

Structural analysis is a branch of Solid Mechanics which uses simplified models for solids like bars, beams and shells for engineering decision making. It's main objective is to determine the effect of loads on the physical structures and their components. In contrast to theory of elasticity, the models used in structure analysis are often differential equations in one spatial variable. Structures subject to this type of analysis include all that must withstand loads, such as buildings, bridges, aircraft and ships. Structural analysis uses ideas from applied mechanics, materials science and applied mathematics to compute a structure's deformations, internal forces, stresses, support reactions, velocity, accelerations, and stability. The results of the analysis are used to verify a structure's fitness for use, often precluding physical tests. Structural analysis is thus a key part of the engineering design of structures.

LS-DYNA

LS-DYNA is an advanced general-purpose multiphysics simulation software package developed by the former Livermore Software Technology Corporation (LSTC), which was acquired by Ansys in 2019. While the package continues to contain more and more possibilities for the calculation of many complex, real world problems, its origins and core-competency lie in highly nonlinear transient dynamic finite element analysis (FEA) using explicit time integration. LS-DYNA is used by the automobile, aerospace, construction and civil engineering, military, manufacturing, and bioengineering industries.

Topology optimization (TO) is a mathematical method that optimizes material layout within a given design space, for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the system. Topology optimization is different from shape optimization and sizing optimization in the sense that the design can attain any shape within the design space, instead of dealing with predefined configurations.

NASTRAN is a finite element analysis (FEA) program that was originally developed for NASA in the late 1960s under United States government funding for the aerospace industry. The MacNeal-Schwendler Corporation (MSC) was one of the principal and original developers of the publicly available NASTRAN code. NASTRAN source code is integrated in a number of different software packages, which are distributed by a range of companies.

Mesh generation Subdivision of space into cells

Mesh generation is the practice of creating a mesh, a subdivision of a continuous geometric space into discrete geometric and topological cells. Often these cells form a simplicial complex. Usually the cells partition the geometric input domain. Mesh cells are used as discrete local approximations of the larger domain. Meshes are created by computer algorithms, often with human guidance through a GUI, depending on the complexity of the domain and the type of mesh desired. A typical goal is to create a mesh that accurately captures the input domain geometry, with high-quality (well-shaped) cells, and without so many cells as to make subsequent calculations intractable. The mesh should also be fine in areas that are important for the subsequent calculations.

Crash simulation Virtual recreation of a destructive car crash

A crash simulation is a virtual recreation of a destructive crash test of a car or a highway guard rail system using a computer simulation in order to examine the level of safety of the car and its occupants. Crash simulations are used by automakers during computer-aided engineering (CAE) analysis for crashworthiness in the computer-aided design (CAD) process of modelling new cars. During a crash simulation, the kinetic energy, or energy of motion, that a vehicle has before the impact is transformed into deformation energy, mostly by plastic deformation (plasticity) of the car body material, at the end of the impact.

A frontal solver, conceived by Bruce Irons, is an approach to solving sparse linear systems which is used extensively in finite element analysis. It is a variant of Gauss elimination that automatically avoids a large number of operations involving zero terms.

Abaqus

Abaqus FEA is a software suite for finite element analysis and computer-aided engineering, originally released in 1978. The name and logo of this software are based on the abacus calculation tool. The Abaqus product suite consists of five core software products:

  1. Abaqus/CAE, or "Complete Abaqus Environment". It is a software application used for both the modeling and analysis of mechanical components and assemblies (pre-processing) and visualizing the finite element analysis result. A subset of Abaqus/CAE including only the post-processing module can be launched independently in the Abaqus/Viewer product.
  2. Abaqus/Standard, a general-purpose Finite-Element analyzer that employs implicit integration scheme (traditional).
  3. Abaqus/Explicit, a special-purpose Finite-Element analyzer that employs explicit integration scheme to solve highly nonlinear systems with many complex contacts under transient loads.
  4. Abaqus/CFD, a Computational Fluid Dynamics software application which provides advanced computational fluid dynamics capabilities with extensive support for preprocessing and postprocessing provided in Abaqus/CAE - discontinued in Abaqus 2017 and further releases.
  5. Abaqus/Electromagnetic, a Computational electromagnetics software application which solves advanced computational electromagnetic problems.
Iterative Stencil Loops

Iterative Stencil Loops (ISLs) are a class of numerical data processing solution which update array elements according to some fixed pattern, called a stencil. They are most commonly found in computer simulations, e.g. for computational fluid dynamics in the context of scientific and engineering applications. Other notable examples include solving partial differential equations, the Jacobi kernel, the Gauss–Seidel method, image processing and cellular automata. The regular structure of the arrays sets stencil techniques apart from other modeling methods such as the Finite element method. Most finite difference codes which operate on regular grids can be formulated as ISLs.

Finite element method Numerical method for solving physical or engineering problems

The finite element method (FEM) is a popular method for numerically solving differential equations arising in engineering and mathematical modeling. Typical problem areas of interest include the traditional fields of structural analysis, heat transfer, fluid flow, mass transport, and electromagnetic potential.


hp-FEM is a general version of the finite element method (FEM), a numerical method for solving partial differential equations based on piecewise-polynomial approximations that employs elements of variable size (h) and polynomial degree (p). The origins of hp-FEM date back to the pioneering work of Barna A. Szabó and Ivo Babuška who discovered that the finite element method converges exponentially fast when the mesh is refined using a suitable combination of h-refinements (dividing elements into smaller ones) and p-refinements. The exponential convergence makes the method very attractive compared to most other finite element methods, which only converge with an algebraic rate. The exponential convergence of hp-FEM was not only predicted theoretically, but also observed by numerous independent researchers.

Discontinuity layout optimization

Discontinuity layout optimization (DLO) is an engineering analysis procedure which can be used to directly establish the amount of load that can be carried by a solid or structure prior to collapse. Using DLO the layout of failure planes, or 'discontinuities', in a collapsing solid or structure are identified using mathematical optimization methods. It is assumed that failure occurs in a ductile or 'plastic' manner.

The PLPAK developers, BE4E, describe it as "The PLPAK is special purpose software package for structural analysis of building slabs and foundations based on the Boundary Element Method". The PLPAK uses the shear-deformable plate bending theory according to Reissner.

VisualFEA

VisualFEA is a finite element analysis software program for Microsoft Windows and Mac OS X. It is developed and distributed by Intuition Software, Inc. of South Korea, and used chiefly for structural and geotechnical analysis. Its strongest point is its intuitive, user-friendly design based on graphical pre- and postprocessing capabilities. It has educational features for teaching and learning structural mechanics, and finite element analysis through graphical simulation. It is widely used in college-level courses related to structural mechanics and finite element methods.

SmartDO is a multidisciplinary design optimization software, based on the Direct Global Search technology developed and marketed by FEA-Opt Technology. SmartDO specialized in the CAE-Based optimization, such as CAE, FEA, CAD, CFD and automatic control, with application on various physics phenomena. It is both GUI and scripting driven, allowed to be integrated with almost any kind of CAD/CAE and in-house codes.

GetFEM++

GetFEM++ is a generic finite element C++ library with interfaces for Python, Matlab and Scilab. It aims at providing finite element methods and elementary matrix computations for solving linear and non-linear problems numerically. Its flexibility in choosing among different finite element approximations and numerical integration methods is one of its distinguishing characteristics.

Ernest Hinton

Ernest Hinton was a British civil engineer and engineering professor. He was born in Liverpool, England in 1946 and was educated at University of Wales Swansea. After receiving the BSc (1967), MSc (1968) and PhD (1971) at Swansea he joined the faculty of the Department of Civil Engineering where served until his death in 1999.

ACTRAN is a finite element-based computer aided engineering software modeling the acoustic behavior of mechanical systems and parts. Actran is being developed by Free Field Technologies, a Belgian software company founded in 1998 by Jean-Pierre Coyette and Jean-Louis Migeot. Free Field Technologies is a wholly owned subsidiary of the MSC Software Corporation since 2011. Free Field Technologies and MSC Software are part of Hexagon AB since 2017.

FEATool Multiphysics

FEATool Multiphysics is a physics, finite element analysis (FEA), and PDE simulation toolbox. FEATool Multiphysics features the ability to model fully coupled heat transfer, fluid dynamics, chemical engineering, structural mechanics, fluid-structure interaction (FSI), electromagnetics, as well as user-defined and custom PDE problems in 1D, 2D (axisymmetry), or 3D, all within a graphical user interface (GUI) or optionally as script files. FEATool has been employed and used in academic research, teaching, and industrial engineering simulation contexts.

References

  1. ↑ Roith, B; Troll, A; Rieg, F (2007). Integrated Finite Element Analysis (FEA) in three dimensional Computer Aided Design programs (CAD) - overview and comparison. Paris: ICED.
  2. ↑ Zimmermann, Martin (2008). Theorie und Implementierung verschiebungsbezogener Schalen als finite Elemente im Maschinenbau. Shaker. ISBN   978-3-8322-7528-0.
  3. ↑ Frisch, Michael (2015). Entwicklung eines Hybridalgorithmus zur Steifigkeits- und spannungsoptimierten Auslegung von Konstruktionselementen. Aachen: Shaker. ISBN   978-3-8440-4028-9.
  4. ↑ Frisch, Michael; Deese, Kevin; Rieg, Frank; Dörnhöfer, A (2016). Weiterentwicklung und Einsatz eines Verfahrens zur Topologieoptimierung zur Effizienzsteigerung in der Konzeptphase. Bamberg: NAFEMS. ISBN   978-1-910643-03-7.
  5. ↑ Bendsoe, M.P.; Sigmund, O (2004). Topology Optimization. Springer. ISBN   3-540-42992-1.
  6. ↑ Frisch, Michael (2015). Entwicklung eines Hybridalgorithmus zur Steifigkeits- und spannungsoptimierten Auslegung von Konstruktionselementen. Aachen: Shaker. ISBN   978-3-8440-4028-9.
  7. ↑ Use at the University Ravensburg-Weingarten, Fakulty for mechanical engineering, lecture Finite Elements, under Edmund Böhm. (as seen on 27/08/2012.)
  8. ↑ Use at the University of Ioannina, Department of Mathematics Institute for Mechanics, Greece, lecture Introduction to Finite Flements, under Georgios E. Stavroulakis (since 2015 continues at the Institute of Computational Mechanics and Optimization COMECO page at the Technical University of Crete)
  9. ↑ Institute for Acoustics, America, Cameron P. Reagor.(as seen on 27/08/2012.)
  10. ↑ Facultad de Ingenieria, Argentina,Analisis Numerico I. (as seen on 27/08/2012.)
  11. ↑ L’Universita Di Cagliari, Dipartimento di Ingegneria Strutturale, Italy.(as seen on 27/08/2012.)
  12. ↑ Faculty of Mechanical Engineering, Laboratory for intelligent CAD Systems, Slovenia Bojan Dolsak. (as seen on 27/08/2012.)
  13. ↑ Faculty Bartin Orman, Turkey, Gökhan Gündüz. (as seen on 27/08/2012.)
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