The press conference of the Technical University of Liberec (TUL) and BUT took place in the buildings of Klokner State. During the oldest independent scientific work, the participants recalled the existence of the state, presented selected projects and thought about new possibilities for construction.
Among Klokner’s most closely watched projects are the long-term construction of the Prague Bridge and the current cement sms 3D printing plant. Here, interested persons could familiarize themselves with the classic methods of structural testing and the possibilities of using industrial robots. Until recently, this revolved around applications in the engineering and manufacturing industries, but with the wave of automation and the emergence of Industry 4.0 principles, robotics will gradually reach areas where it does not. has not been used so far. One of these areas is construction and architecture.
First, the construction status of the bridge bridge
Before the stopped press conference, we talked about the current situation in the testing industry, the state of the bridges. “In the case of bridge structures, the static or dynamic function of the structure, its reliability at serviceability limit states, the number of models and the input variables used in the structure are checked. For me, mechanical, electrical and optical devices or automated systems are used“Explains Eng. Miroslav Vok and shows the results of one of the many static tests, which showed deformations of the supporting structure during short-term loading, compression of the bearings and settlement of the sub -structure. Climatic conditions were also recorded, which could have significantly affected the variables. The objective was to determine the total value of the deflection of the main load-bearing structure and its permeable and permanent component. In the tests of dynamic loading, the essential characteristics of the natural frequency, i.e. the natural frequency, corresponding to the natural forms and the damping of the attenuation, were observed by analysis of experimental model.
“In the case of subtle cells, there is a risk that pedestrians cause resonances, which limits the applicability of these structures. The result is then compared to the designer’s seepage assumptions and the deviation must be within the limits prescribed by the standard” warns Miroslav Vok and shows the current monitoring of the Prask bridge. Currently, thermal stresses (Hlvkv Bridge, Legi Bridge) or deformations of thermal inks (Libesk Bridge, Negrelli Viaduct) have been monitored for a long time on the bridges of cracks Among the constructions followed, the lightweight concrete included, in particular at SOKP via Berounka, or at the Lochkov tunnel (optical fiber strain gauges), and via Chomutovka on the Velemylevsi bypass (string strain gauges), where it is possible to follow long-term concrete bearing structure incidents.
We are working on future projects within Industry 4.0
Representatives of Klokner State, BUT and the University of Liberec call 3D printing the projects of the future. Together they develop a printhead, a zazen tester and a robotic arm that will carry generations of printheads. The specialists of Klokner’s concrete laboratory work on the development of cement composites for printing and provide valuable information on the right 3D printers – test bench and head impressions.
“The Technical University of Liberec (TUL) is the guarantor of the 3D STAR project, which aims to develop a robotic arm that will be easy to transport to the construction site and print several floors of the building directly in the city. We design a Printing Mantis mobile robotic device, which is moved after construction and gradually manages to print vertical and horizontal structures“To Ji Suchomel of the Faculty of Arts and Architecture TUL, the spiritual father of the 3D STAR project.
The test device with a movable printhead was developed at TUL, and another darkness has developed a robotic arm model that can describe any curve and will have a printhead in the future. In the project, the TUL interfaculty team connected the world with the BUT fissure and the state of Klokner, its employees are specialists in the field of materials engineering, and in the project, the mixture for mixtures of concrete and cement. The entire test bench was delivered to Klokner, assembled and commissioned.
“Our goal was to develop and optimize cement mixes for this specific printing process to eliminate hunter efforts from the printing process in the future. The components must be properly selected, mixed, beaten when printing until the optimum consistency of the cement composite and thus set the appropriate printing speed according to the current requirements of the specific construction.“Explains David tek, head of the concrete laboratory of the Department of Experimental and Micro Methods of the Klokner BUT, and adds:”We have experience in 3D printing and we have a very sunny material and technical warehouse. We know from around the world that there is a suitable cementitious composite, and this material has been developed and applied. The mixture gradually took about 2 years. The development of the optimal mixture is estimated to take several months…”
He gave the means to complete the robotic devices
The first experiments follow one another, the test bench now prints from a cement composite with a grain size of up to 1 mm with the addition of a plasticizer and other modified additives. In some printheads, it is necessary to add a solidified accelerator to the mix in some applications to provide immediate stability when printing complex elements. In addition to the composite itself, experts from the state of Klokner subject the printed samples to tests in terms of maximum loads, material parameters but also durability. The entire mixer and printing system can continuously print a concrete object with a floor plan size of 3×1.5 meters and a height of up to about 1m.
The 3D STAR project was launched in 2018 and ended in 2022. As part of the call for pre-applied research, for which TUL received a grant of more than 72.5 million crowns, leaders must learn the main principles of a functional robotic arm. and its system and create working robot models. In this case, the head prints, and also have samples of these construction structures. To complete the real zazen for the impression of the buildings, it will however be necessary to put resources. “Monitoring of the Business and Innovation operational program for competitiveness. However, for the duration of the developed development, it is necessary to find an economically strong industrial partner who sees the future in this technology.concludes Petr Zelen of the Faculty of Mechanical Engineering TUL, the main guarantor of the project.
These objects require the need for interdisciplinary cooperation
The comprehensive 3D printing system uses the experience of researchers from various branches of construction, combining materials in engineering, programming, engineering and architecture, according to the information. In the field of 3D additive manufacturing, for example, he collaborates with the Federico Diaz studio to create a sculpture in the Boslavka building.
“The experience of printing on white 3D printers using conventional materials (plastic) is used here for the development of concrete printing. The staff of the experimental department develops a composite cement mixture with special properties directly for the additive form of concrete impression. The field of mechanics brings its experience in the design of products, extrusion and printing systems. Finally, a very important element is the optimized software itself, in which the required object is distinguished by individual print layers and the general head trajectory generating so that the print is as continuous as possible.“Notes Ing. arch.Oto Melter and according to the need for active cooperation with programmers of robotic systems.
“Due to the shift of automated systems work from traditional design and physical constructions to programmed motion paths, the construction engineering profession in these areas of construction is beginning to overlap with the robotic systems programmer profession. Therefore, programmed machines have no problem with any shape, mixing ratio and precision to millimeter, milliliter and gram. Exactly changing not only the input parameters, but also the input, i.e. the control of the printed object and the feedback, greatly expands the possibilities for process optimization in the entire impression» Adds and points to zazen.
Printing takes place on the TEST BED plotter, which can be freely adapted and interfered with the technology itself. We are currently testing different types of printheads, depending on the type of mixture to be printed, the shape of the object, the speed and the method of printing. The cement composite is adjusted for its consistency, the number of individual components and the reinforcement with the help of the dispersion of the lift according to the technological requirements and the requirements for the resulting mechanical and physical parameters of the object used. The possibilities of the material turn out to be very different – from printing concrete to common strength and printing with very high-quality concrete.
“The development process will reach a two-round state where it can print objects with as little human activity as possible, automating the whole process from mixing mix to printing the required object, not only in laboratory. These objects and their parts are tested in the laboratory’s sealing machines and the results form the basis of all models. These are again processed so that the resulting object not only meets the aesthetic requirements, but also the static requirements. For example, we are currently working on creating elements for p, which will use all the advantages of 3D printing“Add document. Ing. Ji Kolsko, Ph.D., Klokner State Editor.
Photo: Ji Ryszawy, Kloknerv State (K)