The young DIANA was a tool for the analysis of real structures and TNO was lucky to obtain contracts for the analysis of some complex off-shore structures in 1975. It turned out that software development and structural analysis required a lot of computer activity and that the bottleneck for progress was the remote computer services. To perform the modeling of the structure and interpretation of the analysis results, the need for mesh generation and plotting facilities became obvious. Furthermore, particularly for the analysis of large reinforced concrete structures, it would be desirable to include nonlinear phenomena such as cracking of concrete and plastic deformation of steel. To cope with all these problems and requirements, in-house computing facilities were urgently needed.

In 1975 TNO-IBBC purchased its first mini-computer, a Harris/4 with about 48Kb of core-memory and 2 x 10 Mb of disk space. It was chosen because of its 24-bit architecture, which yielded more accurate analysis results than the popular 16-bit PDP-11/45 of Digital Equipment Corporation. However, because of the lack of memory, many programming "tricks" had to be used to get a feasible implementation. One of these tricks was the development of the file and memory management system FILOS which, in modified form, still serves as a special database management system for DIANA. To facilitate the creation and checking of the finite element model, two new modules were developed: MESH for automatic mesh generation and GRAPHI to display the model and its analysis results. Both modules came available in 1977, and were used to analyze parts of the `Oosterschelde Deltawerken' in Zeeland. At that time, DIANA's reinforcement modeling option was a unique feature, not available in competitive finite element codes.

Having the Harris computer in-house, the turn-around time of analysis and development jobs decreased dramatically. Moreover, new sponsors became interested in TNO's R&D activities: the Dutch MATS and CUR research funding organisations. The CUR organised a large Concrete Mechanics project which lasted until 1990 and was carried out in cooperation with the Technical Universities of Delft and Eindhoven and with the Dutch Ministry of Transport and Public Works.

Both the in-house computing facility and the research funding enabled the development and implementation of more advanced analysis methods, this resulted in the first working versions for nonlinear and dynamic analysis around 1978. DIANA's first brochure tells all about the facilities at that time: for instance 3-dimensional analysis of concrete structures, including crack analysis and plastic deformation of embedded steel reinforcement.

In 1979 the Harris computer was replaced by a more powerful and accurate machine: a 32-bit VAX-11/780 of Digital Equipment Corporation, running the VAX/VMS operating system. Also at that time, the first version of the DIANA User's Manual was completed, still in Dutch and printed on a line printer. DIANA had now grown to about 200.000 statements and gradually, the attractiveness of the code was also recognised by engineering offices and researchers outside TNO. For this reason, the first professional executable product version of DIANA was prepared. The DIANA-1 release was delivered to the Dutch Ministry of Transport and Public Works in the Hague in 1980, to run on a UNIVAC-1108 main frame computer.

A VAX-11/780 at that time cost somewhat more than half a million Dutch guilders (US$200.000), which was more than small engineering consultant companies could afford. TNO therefore realised that to enter the market with an application software for structural analysis, it would be essential to have it running on low-cost computers. However the personal computer was not, in those days, sufficiently powerful for an application like Finite Element Analysis.

Fortunately, there was an R&D project going on at TNO to develop a low cost, but powerful micro computer for Computer Aided Design applications: the GEMINIX, based on the Motorola MC-68000 processor and probably the world's first micro computer running the UNIX operating system. DIANA was successfully ported to the GEMINIX and in 1983 this combination was installed at three customer sites: two engineering consultant companies and the Public Works department of Rotterdam.

As their number increased significantly, the external users wished to organize themselves. This led to the establishment of the DIANA Users Association in 1984, a platform for exchange of users' experience, which also indicated priorities for new developments toward TNO. This led to the DIANA-2.0 release in 1988, with new modules for potential flow analysis, and for connection to external pre and post processors. The 2.0 release came with a user's manual and a user's course and text book, now all in English which allowed DIANA to go international. The first customer outside The Netherlands was the University of Darmstadt in Germany.In the late 1980s, the research community discovered DIANA's potential as a software development environment in addition to its service for end-use. TNO's major partners asked for access to the source code and the associated programmer's toolkit to establish their own developments in DIANA. This marked the birth of the DIANA Foundation on May 9, 1989, a joint initiative of universities, research institutes and industrial partners. The role of TNO was, and is, to transfer these developments to the product version of DIANA, including quality assurance, documentation and maintenance, to achieve continuity of the developments. Since January 1991 the Foundation has been recognized and approved by the Netherlands Organization for Scientific Research (NWO) as Expertise Center for Computational Mechanics.

In order to provide high quality maintenance and development for DIANA, TNO appointed DIANA Analysis BV to manage sales, marketing, promotion, and first-line support of DIANA in 1990. The 3.2 release was the first release to be distributed and supported by DIANA Analysis BV. It came with new modules for fracture mechanics, dynamic response, and stability analysis. The element library was extended with flat shell and interface elements, and with elements for groundwater flow analysis. DIANA-4.1 was released in 1991. Significant extensions in this release were an iterative solver, phased analysis, indirect displacement control in nonlinear analysis, and a new family of orthotropic membrane elements.

The members of the DIANA Foundation asked for more information about the DIANA programming environment. Therefore TNO developed a programmers course which was given for the first time in 1992. The programming environment was primarily supported on powerful workstations under UNIX. However, the power of personal computers had increased to such an extend that the users community asked for a port to the MS-DOS operating system. This was established in 1993 with the DIANA-5.1 release. Important additions to the analysis features in this release were a substructuring technique in the solution procedure, stability analysis with imperfections, nonlinear analysis control improved with arc-length and automatic load control, and new modules for parameter estimation, and pipeline analysis. The element library was extended with higher order elements for various families and with layered elements.

In 1994, the DIANA user community had grown to such an extent that it became time for the "First international DIANA conference on computational mechanics", jointly organized by DIANA Analysis BV, the DIANA Foundation, the DIANA Users Association, and TNO. The next release was DIANA-6.1 in 1996, with improved meshing facilities, an iterative solution method optimised for vector and parallel computers, the analysis of wind and water wave load, a line search algorithm for nonlinear analysis, nonlinear dynamics, post-buckling, and contact analysis. New material models for clay and concrete were added, as well as models for viscoplasticity and viscoelasticity. The new user-supplied subroutine option supported a general material model of particular interest for R&D sites.

With respect to postprocessing, the 6.1 release brought facilities to determine and plot influence lines and to make contour plots. The external pre and post processor FEMGV was coupled to DIANA to provide an interactive graphics interface, including general meshing and color plots of analysis results.

On the occasion of DIANA's 25th birthday, the "Second International DIANA Conference on Computational Mechanics'' was held (in June 1997). As DIANA was, and still is, characterised by two key-words: research and end-use, the conference brought together researchers and end-users engaged in finite element modelling, plus new developments in computational mechanics. The titles of the various sessions indicate DIANA's wide variety of applications: "Concrete mechanics and concrete structures", "Geomechanics and soil-structure interaction", "Steel and composite structures", "Computational mechanics of materials", and "Finite element technology and software development".

In 1998 DIANA-7.1 was released. An important improvement was the enhanced DIANA environment for the FEMGV-5.2 pre and post processors. Another new feature in the user-interface was the online version of the users manual, to be used via a web-browser. The 7.1 release offered new material models for concrete cracking and crushing, an option to simulate corrosion of reinforcement steel, a module for mobile load analysis, and extended options for geotechnical analysis. From the 7.1 release onwards, DIANA also supported the MS-Windows platform for PC's.

DIANA-7.2 was released as an upgrade to 7.1 in 1999, now combined with FEMGV-6.1 with many enhancements for interactive graphics pre and post processing and a fully integrated on-line user's manual. Another important enhancement was the availability of new constitutive models, particularly suited to analyse the liquefaction of saturated soil due to earthquakes. Together with DIANA-7.2, TNO introduced a new product called `Micro-DIANA'. For the benefit of a reduced license fee, Micro-DIANA has all the analysis capabilities of the mother program but allows a limited number of nodes in the finite element model.

In 2000 the development of two major product lines was initiated:

Shell International Exploration and Production BV commissioned TNO to develop special versions of DIANA for their private use. The choice for the two product lines required a restructuring of the code such that components with clear tasks are identified which can easily be combined in new applications. In parallel, Femsys Ltd extended FEMGV with specific functions for DIANA, such as reinforcement preprocessing, hierarchical property forms, menu configuration on selected model types, visualisation of cracks etc. The year 2000 was a very successful year worldwide for new sales and the number of licenses increased by 40%.

In 2001, the first results of the research project '4D-Computing' became available in the development version in the form of two new solvers: Sparse Cholesky and ILU-preconditioning. This project aimed at speeding-up DIANA and was supported by the D.O.V. In the same year DIANA-2D was introduced, a special version for the analysis of two-dimensional models.

The first major release of the new millennium was introduced in 2002 as DIANA-8.1. This version came with a fully integrated pre and post processing environment iDIANA, derived from FEMGV-6, and a graphical interactive control of analysis commands. New material models became available, particularly suited for analysis of soil and concrete, like Delft Soft Soil, Hoek-Brown, and Rankine Hill anisotropic. Also added were models for young hardening concrete. Among the new analysis capabilities was a module for spectral response analysis and the new solvers.

In October 2002 the "Third DIANA World Conference'' took place in Tokyo. By this time, Japan had become the most important export market for DIANA. The emphasis of the conference was on the application of advanced computational models in civil engineering applications.

In 2002, TNO prepared a new organisation around DIANA: a company named TNO DIANA BV was founded and in the beginning of 2003 all technical activities were transformed from TNO Building and Construction research to the new company. Also the marketing and sales activities, until then handled by DIANA Analysis BV, were transferred to TNO DIANA BV. At the same time TNO DIANA BV became the owner of Femsys Ltd. A new organisation was therefore created in which commercial and technical activities were integrated serving DIANA users worldwide in an optimal way.

In May 2003, the Second edition of release 8.1 was made available. In this version the remaining applications, such as Fracture Mechanics Analysis and Beam Cross-section Analysis, were included in the graphical user interface. Also some new line interface elements for shells were introduced.

At the end of 2004 DIANA-9 was introduced. This version offered a completely new interactive Graphical User Interface. Various analysis functions were also added. e.g. new automatic nonlinear solution procedures, complete plane strain elements, and improved options for geotechnical analysis.

In 2005, a strategic decision was taken to expand the business from the high-end niche market for advanced nonlinear analysis software that was traditionally served by the DIANA software, to the markets for design and analysis software. In daily design practice, the ease of use is of prime importance and analysis tools must be tailored to the terminology and working procedure of design engineers. At the same time, we have chosen to focus the inhouse software development activities on the DIANA finite element solver functionality and to look for strategic partners for the development of pre and post processing software components - both for the high end general purpose users as well as new application oriented design software products.

In December 2005, TNO DIANA BV entered into a strategic alliance with MidasIT, based in Seoul in South Korea. The alliance joined forces in product development and distribution of each others products. MidasIT was to focus on the distribution of products in Asia and TNO DIANA on the distribution of products in Europe and the United States. The advanced nonlinear analysis functionality would be developed at TNO DIANA in Delft, whereas MidasIT would take the lead in the development of the design applications and the pre/post processing programs.

DIANA version 9.2, which was the first version of DIANA integrated with the Midas FX+ pre and post processor, was introduced at the end of 2006. This new combination impressed the market with its powerful combination of robust nonlinear 3-dimensional analysis functionality and easy to use intuitive pre/post processing programs.

Earlier in 2006, the Femsys office in Leicester was transferred into a TNO DIANA UK office in Woking, close to London. The office focused on the distribution of the MidasIT products, midasCivil for bridge design and analysis and midasGen for the design of buildings and more general structures.

In 2007, the first international bridge seminar was organized in London on the topic of Integral bridges, followed by the 2008 seminar on Cable-stayed bridges and the 2009 seminar about Construction stages in Bridge engineering.

Parallel processing of solvers and full 64-bit architecture was offered in DIANA version 9.3 in 2008 and the FEMGV program was also transferred to 64-bits architecture in the same year. This development opened the route to faster analysis of larger models and the development got an enormous boost in the following year.

Since 2005, in a close co-operation with the DIANA User Association, the international User meeting has been organised at varying locations in Europe. During these events, users exchange experiences in using the software and wishes for new developments are discussed between users and developers.

In 2008, MidasIT and TNO DIANA BV decided to strength the co-operation by integrating DIANA as the solver in the fully integrated product, midasGTS, for 3-dimensional geotechnical and tunneling analysis. This product offered CAD-type model definition with fully automatic meshers and non-linear solvers in an integrated program. This fully integrated product could be used efficiently by design engineers who are not necessarily experts in finite element analysis.

A major new DIANA version (9.4) was launched in 2009 and the integrated GTS-DIANA program was introduced in the Spring of 2010. This new DIANA version offered more parallel processing functionality, as well as a wide range of new finite element functions such as bond-slip options for embedded reinforcements, which could also be used to model pile foundations, additional soil/rock models and more.

Early in 2010, DIANA 9.4.2 became available offering new element types, eg. curved shell elements with drilling rotations and linear fluid-structure interface elements, in the D-min soil material model, and additional analysis functionality.

In the Autumn of 2010, DIANA 9.4.3 was released. In this version the possibility to use precompiled library files for user-supplied subroutines, plus two new analysis types for sequential linear analysis and reinforcement grid design checking, were introduced.

As of January 2011, TNO DIANA BV took the decision to stop the sales and marketing of MidasIT products, focusing instead on the sales and marketing activities of the flagship product, DIANA. TNO DIANA BV and MidasIT continued their existing technical collaboration and technology transfer between the respective products. Throughout 2011, TNO DIANA BV continued to support its existing MidasIT customers providing both technical supports and upgrades to software.

In January 2012 came the next iteration of the DIANA software, DIANA 9.4.4. Two new application modules were made available which signified a leap forward in the analysis of reinforced concrete.

The module “Reinforcement Design Checks” gave civil engineers the opportunity to optimise the design of structures by assessing the additional capacity within the existing reinforcement. Running alongside this, the new module “Stiffness Adaptation Analysis” made it possible to predict crack patterns, the size of crack openings, plasticity onset, force distribution and deformations in serviceability limit state.

For geotechnical engineers the ability to carry out a Strength Reduction Analysis (C-Phi) was made available in a new module. This allowed the strength characteristics of the structural material to be reduced by factors leading to the loss of stability, typically used in slope stability analysis.

Despite all the functional extensions in the last decades, and the combination of DIANA’s analysis strengths with the FX4D pre/post processing power, and ease of use, industrial engineers still hesitated to make the step to advanced analysis. In 2013, it became clear that in order to bridge the gap between engineering practice and the advanced capabilities of real 3-dimensional analyses in DIANA, the modelling, analysis and result-checking must be integrated in a flexible and customisable integrated software environment. In the same year, TNO DIANA BV decided to start the development of a new state of the art graphical integrated environment for the DIANA analysis program. This included geometrical modelling, automatic mesh-generation and fast visualisation of models and results, and the ability to present analysis results inline with international design codes. The development priorities for the new DIANA Interative Environment were first to replace the traditional iDIANA and FX4D general purpose pre/post processing programs, and then to customise the same software environment to specific applications, this allowed engineers who are not expert in nonlinear analysis, to carry out such analyses for specific applications in a fast and easy way.

In 2014 there were two releases of DIANA (9.5 & 9.6), these releases introduced the new Mesh Edit graphical user interface, which was based on the new graphical development. Mesh Edit offers a streamlined and user friendly interface which will ultimately enable users to use all the functionality of DIANA within one program.

The initial iteration of MeshEdit gave the users the ability to import their model from FX+ or iDIANA and then define supports, loading, materials and analysis requirements; carry out the analysis; and deal with post processing. In 9.6 these features were extended to include a scripting console, the introduction of mesh sets and further post processing functionality.

In 2016, the landmark release of TNO DIANA BV, DIANA10, was released to present state-of-the-art technology in both the new graphical user interface (GUI), as well as optimisation methodologies at kernel level to lead the CAE market associated with civil and geotechnical engineers. The unique design and implementation of the new and fully integrated pre-/post-processor of DIANA enables users to take advantage of the latest operating systems applications based on two different platforms (Windows and LINUX).

CAD import features, as well as powerful geometry modelling tools, are available based on the embedded Parasolid geometry engine in this version of DIANA.

In addition, the latest and powerful mesh engines were adapted for 2D and 3D models based on CM2 MeshTools including hybrid mesher to enhance the quality of the final mesh for any complex geometry.

Additional flexibility in terms of model definition and analysis setup was introduced through a powerful scripting language – Python. The log of the whole modelling process, including geometry definition, analysis setup and post-processing procedures were now automatically projected in a text file and users were then able to re-load the scripted file in conjunction with other Python commands to perform a varity of analyses based on the reference model file.

And finally, a new parallel processing feature of the element loop has been added to the existing parallel processing options at solver level to speed up the process of setting up linear elastic stiffness matrix, calculating nonlinear stresses and internal forces and setting up tangent stiffness matrix. With all the new features and analysis capabilities available in this latest version of DIANA, at the forefront was the introduction of a new paradigm to address the developing challenges in civil and geotechnical engineering applications based on the latest and fast developing technology in the field of finite element analysis.

As of 1 July 2016, TNO DIANA BV changed its name to DIANA FEA BV. After 14 years of trading as TNO DIANA BV and the worldwide success of the flagship product DIANA, the decision was taken to change the name to reflect the name of the product and place more emphasis on DIANA rather than its ties to TNO. DIANA FEA BV remains a TNO Company, but stands alone as a software development company focusing on finite element analysis for the building industry of the future.