Dep. Computer Aided Eng. Graphics

The aim of this work was to improve the constitutive model of the human mandible and dentition system by taking into account the non-linear material properties of the structural boney matrix that forms the human jaw bone or mandible. Due to the specific structure of the jaw bone the time dependence of the mechanical properties also forms an important stage of the quantification process. The lack of specific experimental data of this type of material prevents the implementation of these properties into finite element simulations which results in poor quality modelling. Here an attempt was made to determine elastic and viscoelastic mechanical characteristics of the compact bone tissue forming the mandible. The elastic properties of compact bone were determined experimentally from 3 point bending tests and the viscoelastic properties were evaluated from creep tests in compression. A particular human jaw from this complex study was used to reconstruct a geometric model for further numerical experiments.

This study describes the development of a constitutive law for the modelling of the periodontal ligament (PDL) and its practical implementation into a commercial finite element code. The constitutive equations encompass the essential mechanical features of this biological soft tissue: non-linear behaviour, large deformations, anisotropy, distinct behaviour in tension and compression and the fibrous characteristics. The approach is based on the theory of continuum fibre-reinforced composites at finite strain where a compressible transversely isotropic hyperelastic strain energy function is defined. This strain energy density function is further split into volumetric and deviatoric contributions separating the bulk and shear responses of the material. Explicit expressions of the stress tensors in the material and spatial configurations are first established followed by original expressions of the elasticity tensors in the material and spatial configurations. As a simple application of the constitutive model, two finite element analyses simulating the mechanical behaviour of the PDL are performed. The results highlight the significance of integrating the fibrous architecture of the PDL as this feature is shown to be responsible for the complex strain distribution observed.

The present time can be characterized as an era of digital revolution which has resulted in a creativity burst in different design applications. Nowadays Computer Aided Architectural Design (CAAD) undoubtedly is recognized as a design media rather than a simple computerized design tool and is widely accepted in architectural practice. The general goal architects pursue is to visually express design and illustrate their projects or ideas using both professional experience and personal computerized creative skills. Rapid advancements in Information Technology (IT) are still under way and are widely used to communicate architectural design projects. CAAD is a particularly dynamic field that is developing through the actions of architects, software developers, researchers, technology, users and society alike. New methods and terms are introduced and developed, just to mention a few of them -Human Computer Interaction, Computer Supported Collaborative Work, Virtual Reality (VR), Rapid Prototyping (RP), etc. 3D modeling, virtual buildings, single building models, and other ideas have been widely used during the last two decades. The main concept focuses on three main benefits: 1) The generation or extraction of 2D drawings from 3D building models thus improving productivity in documentation, 2) Visualization, animation, including virtual reality scenes from the same model, and 3) The use of data embedded in objects contained in the model for the purposes of generating schedules and lists of materials. However, not always these advancements have been effectively used in an everyday design practice. The paper deals with an exploration of some of these new information technologies, how they can be integrated into architectural design process. The introduction of contemporary CAAD knowledge into the university curricula is discussed as well. Academic courses basically are about the development of computer aided creative and problem solving skills in context with fast changing CAAD media. It becomes more difficult to teach the common principles behind the software which are general and will most likely survive ever-changing software versions. Limited university class contact hours for the subjects do not allow developing detailed courses for training particular software. An evaluation of the promptitude of the architectural students at Riga Technical University for the self sufficient problem solving tasks was performed. The statistical analysis of the results of the research covering 2 academic years is presented in the discussion. A strong linear correlation was found between the time to complete particular exercise and CAD competence level among the students. Proficent users spent only 7 minutes on this while the beginers 110-130 minutes, thus clearly demonstrating the importance of CAD training in effective use of software. Current developments in architectural problem solving education are presented and discussed.

The paper outlines the importance of engineering graphics skills in the background knowledge of engineering education. This topic becomes especially important at the age of rapid economic and technologic changes in the society. An approach will be discussed about what and how we teach to develop the present-day engineering graphics communication skills in Riga Technical University in the context of general infomedia literacy.

During the Spring 2011 semester, an engineering graphics literacy assessment was developed by a visiting Fulbright Scholar at North Carolina State University (NCSU) in USA. The assessment was developed for constraint-based modeling course and tested at NCSU. The faculty from two other universities joined the project to test this methodology. The students from Latvia University of Agriculture (LUA) in Latvia in Spring 2011 and later during the Fall 2011 semester the students from two sections at Riga Technical University (RTU) in Latvia participated in the test using SolidWorks 3D modeling software. All the 75 students from three universities were asked to create 3D models for seven parts given in an assembly drawing of a mechanical device within two hours time period. The parts in the assembly ranged in complexity from a simple ball to a complex valve body. Students were given a ruler to measure parts on the B-size third quadrant (A3 size first quadrant for Europe) drawing and determine sizes of geometric elements based on the given scale (2:1). There was a positive relationship between the scores on the activity and the pace at which each student completed the parts. It was difficult to compare the test scores on the modeling assessment and other measures in the course (final project, final exam, and final course average) because universities have different grading system. This paper summarizes how students performed on the assessment (number of parts correctly modeled, scores, total time, etc.), reports analyses of relationships between their scores on the assessment and other measures in the course, and also presents ideas for future studies. An average test scores in two universities were significantly lower than in LUA where the students had much extensive descriptive geometry and engineering graphics background.

Building Information Modelling (BIM) is a process of generating and managing building data during its life cycle which involves representing a design as virtual objects, which carry their geometry, relations and attributes. BIM design media allows an extraction of different views from a building model for drawing production and other uses. All the different views are automatically synchronized in the sense that the objects are all of a consistent size, location, specification -since each object instance is defined only once, just as in reality. BIM uses 3D, real-time, dynamic building modelling software to increase productivity in design and construction. BIM process co-ordinates products, project and process information throughout new product introduction, production, service and retirement among the various players, internal and external, who must collaborate to bring the concept to life. Universities have to become the initiators of the promotion of BIM ideas not only to the designers and engineers, but much wider public than at present. Universities have to seek contacts/relationships with a view of developing joint actions with industry and enterprises. Particular attention should be paid to Small and Medium sized Enterprises as they account for an enormous part of economic growth and could be the places where the innovations could be introduced easier. There is an evident role for universities to play in lifelong learning and continuing education thought them to offer possibilities of companies to increase competitiveness, productivity and efficiency, total costs estimation, and to become concurrent on the global market.

During the Spring 2011 semester, an engineering graphics literacy assessment was developed by a visiting Fulbright Scholar at North Carolina State University (NCSU). The assessment was developed for constraint-based modeling course and tested at NCSU. The faculty from four other universities joined the project to test this methodology. The students from Latvia University of Agriculture and later during the Fall 2011 semester the students from Riga Technical University participated in the test using SolidWorks 3D modeling software. The group of students at University of Rijeka in Spring 2011 used AutoCAD 3D modeling software, but the students at Siberian State Automobile and Highway Academy used 2D drafting software Kompas. All the 98 students from five universities were asked to create 3D models or make working drawings for seven parts given in an assembly drawing of a device within two hours time period. The parts in the assembly ranged in complexity from a simple ball to a complex valve body. Students were given a ruler to measure parts on the B-size third quadrant (A3 size first quadrant for Europe) drawing and determine sizes of geometric elements based on the given scale (2:1). There was a positive relationship between the scores on the activity and the pace at which each student completed the parts. It was difficult to compare the test scores on the modeling assessment and other measures in the course (final project, final exam, and final course average) because universities have different grading system. This paper summarizes how students performed on the assessment (number of parts correctly modeled, scores, total time, etc.), reports analyses of relationships between their scores on the assessment and other measures in the course, and also presents ideas for future studies. Average test scores in four universities were significantly lower than in Latvia University of Agriculture where the students had much extensive descriptive geometry and engineering graphics background.

Generally, a fractal most often referred to as "a rough shape that can be subdivided in parts, each of which is (at least approximately) a reduced-size copy of the whole." The father of fractal geometry Benoît Mandelbrot formulated this term in 1975. A fractal has a complicated shape. Certain features characterize a graphical representation of the fractal by mathematical equation: it is self-similar, has fi ne structure, and is very diffi cult to describe it using Euclidian geometric language. It might seem like a nice mathematic abstraction, but fractal geometry, as we believe -is the foundation of everything that exists.

This paper proposes a generally new type of macro and megaspace filling honeycombs having quasiregular pentahedral cells with skew hexagonal faces. An existence of spatial cells named pentahedra is demonstrated by topological transformations of hexagonal prismatic honeycomb and is based on a recently discovered Phi relationship within a regular hexagonal tessellation. A geometric symmetry of this honeycomb is studied, filling the space with no gaps or overlaps. Finally it is pointed out that abstract or skeletal analogues of pentahedral honeycomb have effective practical uses by synthesis of artificial man-made macromedium, especially the like of orbital large scale structural systems.

The quality of modern engineering education is directly linked with the students’ ability to create and read the drawings of engineering structures. The subject “Descriptive Geometry and Engineering Graphics” taught in the undergraduate engineering studies develops students’ ability to analyse both the shape and design of real objects and, along with the spatial reasoning, the technical thinking. The development of spatial skills for engineering students is closely related with the success in their future professional career. The new information technologies (IT) offer novel opportunities to enhance the classic teaching approach used so far during mastering quite complicate and extensive courses, like engineering graphics. Augmented Reality (AR) is one of the many challenges of modern IT technologies which recently became available also for education purposes. It is supposed that AR will provide new possibilities to teach the contemporary generation of students in an attractive and more entertaining way. First part of the article describes the results of the application of didactic toolkit AR-DEHAES based on Augmented Reality for development of spatial ability of students. In the second part of the article presented are the examples of 3D objects for the exercises of “Descriptive Geometry and Engineering Graphics” course prepared for the use into AR environment. The use of AR technology facilitates the students to acquire better practical skills in much shorter time during their academic studies and improves the quality of graphic education.

Building Information Modelling (BIM) is a complex process of managing not only design documentation in 3D form but it also includes all the consecutive stages of the design analysis, followed by construction management, and including facility management after the site completion. The success in the collaboration to unite common efforts of architects, constructors and HVAC engineers would make the work of all involved stakeholders more productive because the existing information technologies provide this option already for a long time. The training for effective use of this relatively new and very complex approach from the very beginning of the building lifecycle in the construction industry is even a more complex task. Universities have to join the promotion of BIM ideas not only to the designers and engineers, but to a much wider public than at present. The history of BIM teaching and the approaches used at Riga Technical University (RTU) are outlined in this paper. RTU along with several other universities from Lithuania have joined the EU sponsored Leonardo da Vinci project BIMTRAIN initiated by regional software distributer and developer AGA-CAD which facilitates the BIM implementation through the training.