Papers by Keyword: Material Testing

Abstract: A construction building's structural integrity, material quality, workmanship, and conformity to design specifications were all assessed qualitatively. Potential problems like cracks, corrosion, or subpar construction techniques were found during the examination through visual inspections, material testing, and documentation analysis. Guidelines for upkeep, fixes, or structural improvements were offered to guarantee the building's longevity, security, and adherence to rules. The evaluation sought to improve the building's durability, functionality, and occupant safety while correcting any flaws to preserve structural integrity.

Abstract: Clay is one of the earliest known material used in construction, and the most widely used building material on the planet. Our ancestors have performed the tasks of mixing water with dust to make clay, then shaping it into bricks, bricks into buildings, and buildings into cities for more than ten thousand years. In recent years, 3D printing technology has become increasingly popular thanks to its ability to manufacture complex morphologies and to optimize physical and mechanical properties for specific applications. This study investigates customized 3D clay bricks as a new building material (building component) by employing resources that are eco-friendly, locally available, inexpensive, and driven from recycled sources or waste streams. In this experiment, four different fiber types have been investigated with different clay treatment. The specimens were fabricated in the laboratory and tested with unconfined compression loading. The strength and ductility of the clay specimens were then analyzed based on the experiment results. Several experiments have been conducted during the study for understanding the effects of different fibers when mixed with clay in order to identify which type of fibers and which size has the most effective influence on its compression strength. Furthermore, it has been tested also the water absorption of the 3D printed brick. A case study has been developed to show the actual potential of 3D printed clay bricks for a small housing complex. The project is located in a village near to Abuja, Nigeria, at a time of exponential population increase and associated lack of affordable housing. The 3D printed blocks embed a cooling function, thanks to their geometry and the presence of cooling pipes directly in the wall. The result is a highly flexible envelope, designed to be resilient and energy efficient.

Abstract: A method for processing data from tests of building materials is proposed in order to identify the optimal functional relationships between the physicomechanical characteristics and the technological parameters of building materials. The least squares method (MLS) was used and to improve the accuracy of calculations, a three-level optimization of calculations was introduced using groups of transforming functions (180 items). Taking into account the increased volume of statistical computations, computer subroutines have been developed, which, together with standard MLS computational programs, make it possible to realize the choice of the indicated optimal functional connections.

Abstract: A mathematical model has been proposed for processing data from tests of building materials and obtaining optimal links between the characteristics of the bearing capacity and technological parameters of building materials for the use of these connections in refined design and construction procedures for building structures. To improve the accuracy of the results obtained, a three-level optimization principle was applied using the least squares method and a computational algorithm was compiled that allows us to develop an additional computational subroutine expanding the capabilities of the corresponding standard computer programs.

Abstract: o accurately simulate the foam core in composite parts on a macroscopic scale the morphology, the characterisation, and the nonlinear behaviour of thefoam must be understood properly. Accounting for the heterogeneity and the mechanical properties of the foam core affects the dimensioning of the final part.In the present study the microstructure of the foam samples were characterized using scanning electron microscopy. To determine the bulk material behavior and the strength limitations of the nonlinear foam, shear and compressions tests are performed. All numerical calculations were carried out on the macroscopic level.A basic challenge in the finite element modelling of hyperelastic materials by means of test data is the identification of material model coefficients which are appropriate to describe the behaviour of the considered foam.

Abstract: Hardness measurements can simple, but very useful provide materials mechanical properties. This is atest that is extremely localized in volume and does not affect significantly the structural properties. Theaim of this article is to highlight on influence of the applied load forces to the hardness measurementresults. In engineering practice it is generally the most widely used method of measuring the Vickershardness. This method has a variability of the loading forces in a wide range from nano/micro up tohigh loads in hundreds N. There is a well-known plastic material response, therefore, were taken intoaccount several steels commonly used in technical practice S355 NL+N, 316LVM, 34CrMo-4. Wheninterpreting the results should always point out to the value of the load. In common engineering practiceleads to confusion, or to comparing the hardness of the material obtained at different loads. Thisproblem is quite often occurs at nowadays and needs to be solved. Focus should be not only in termsof results depending on the load, but also from a statistical perspective of scattering measurements atvarious loads. Generally, in the technical practice is discussed independence measurement results ofVickers hardness on applied load, due geometric similarity of indents. When is used different forcesthere is a changed of the hardness results. This phenomenon is known as a size effect. This effect isgenerally related to each mechanical testing of materials. However, engineering practice getting intoconflict with this effect.

Abstract: The material point method is a particle-based method that uses a double Lagrangian-Eulerian discretisation. This approach has proved its functionality for the simulation of large deformation problems. Such problems are frequent in geotechnical engineering, more specifically those related to penetration during pile driving and conventional in situ tests such as the Cone Penetration Test. The shallow laboratory fall cone test is considered in this paper. This test is widely used for the determination of the liquid limit of clays, but it is also used to study the relationship between penetration (h) and the undrained shear strength of clays (s_u). Simulations are verified against laboratory vane shear tests and fall cone tests performed on samples of kaolin clay at different moisture contents. Calibrations using a simple penetration-strength (h-s_u) model are made based on a single coefficient named the cone factor (K). The numerical results closely match both the experimental data and analytical solutions available in the literature.

Abstract: The article presents the results and analysis of long-term monitoring of the bridge across the Odra River on the D47 freeway in the Czech Republic near Ostrava. Structural system of this bridge is formed by a continuous composite box girder with spans from 49 to 102 m. Total length of the bridge is 402 m. The bridge was equipped by strain gauges and force sensors during the construction. The monitoring has been kept on for 10 years. The measured values are compared with the results of calculations.

Abstract: The presented paper introduces the application of the Electronic Speckle Pattern Interferometry (ESPI) technique for measurements of contours of strains and stresses on 3-D surfaces. The paper focuses on three selected applications. Firstly, the methodology for determining the Poisson ratio of a material from tensile tests is described. Secondly, results of calibration verification of a biaxial extensometer used for measurements of shear strain in comparison with the ESPI measurements are presented. Finally, the experimental analysis of stresses in welds is discussed. As mentioned in the paper, the method is very useful for material testing, as well as for measurements on structural parts in service.

Abstract: The development of manufacturing technology is mostly given by economics, environmental trends and the development of cutting materials and machine tools. Manufacturing is a significant part of the worldwide economy. Machining (material removal processes) represents major part of production costs. This paper yield inquiries into the hard and precise milling with a focus on force effects in experimental machining, tool wear and final surface qualities (roughness, micro hardness). The precision machining of hardened steel differs from conventional machining in terms of the hardness of the workpiece materials and the cutting tool materials that are required. Hard materials are characterized by high hardness (> 45 HRC) and abrasiveness. Machining processes require cutting tools of much higher hardness and also higher resistance of the abrasive wear. Recently developed cubic boron nitride (CBN) and coated sintered carbides cutting tools are considered to have the ability of cutting such as steel. CBN cutting tools show good performance during machining of the hardened steel because of their hot hardness and good fracture toughness.