Papers by Keyword: Experimental Investigation

Abstract: This study investigates the compaction behavior of woven flax rovings, a crucial aspect of the preforming stage in composite manufacturing. It focuses specifically on the challenges posed by their inherent heterogeneity and structural variability. Although the durability of flax-based composites is widely recognized, accurate numerical modeling of their processing, particularly for liquid composite molding (LCM), remains limited by the lack of detailed experimental data on roving mechanical behavior, including data capturing the inherent variability of the material. This research used a combined experimental approach, comprising computational microscopy for microscale deformation analysis and macroscopic compression tests, to characterize the mechanical response of flax rovings under compaction. Results highlight the need to develop sophisticated simulation frameworks that account for statistical variations in material properties but also the specificities of the flax roving response, which differs considerably from that of synthetic fibers rovings. The experimental dataset generated provides a valuable basis for identifying material parameters and validating advanced simulation frameworks aimed at improving performance predictions of manufactured components.

Abstract: Laser Shock Processing (LSP) is an excellent surface strengthening technology and an effective method to effectively solve this technical problem. The published literature only reports the LSP research on the blade tenon of large engine, and there is no LSP research on the turbine disk mortise of small engine (helicopter engine) with complex and narrow spatial structure. This paper was carried out Oblique LSP research on the complex structure of key parts of new helicopter engine, and the following research results were obtained: The residual stress of simulation and experiment were analyzed by the least-squares method, the flat-topped order of laser beam was corrected, and the pressure distribution model that better matches the shock wave induced by the flat-top laser beam was constructed; Due to the thin thickness and poor stiffness of the turbine disk mortise, the residual stress of the turbine disk mortise was compared between the LSP finite element simulation and the experiment by using the treatment method of equal laser power density and variable pulse width. The results show that the results of turbine disk mortise experiment were close to those of finite element simulation. The treatment method of equal power density and small pulse width can ensure the effect of strengthening the surface and reduce strain of turbine disk mortise.

Abstract: Natural fibers as reinforcement can be an alternative material with an environmentally friendly profile. The aim of this work is to determine the potential of Indonesian Ramie fiber, as a reinforcing material in cement mortar, by exploring new twisting ideas for natural fibers and the impact of twisting techniques on tensile strength. Long fibers are arranged in four cross-sectional areas and also in different numbers of constituent layers, as 2 ply and 3 ply. The spinning process contributes to the final yarn result which the process is carried out in the same direction for each ply, but to unite each ply it is necessary to rotate the direction of rotation and the direction of the single fiber yarn (opposite way). Twisted Ramie fiber yarns were tested for tensile strength using the Universal Testing Machine (UTM). It showed that comparing at the same weight of 24 gr twisted yarn, 3 ply twisted yarn shows the highest tensile strength value as much as 110,32 MPa than 2 ply as much as 96,56 MPa that indicates that the number of ply affects the tensile strength of the yarn.

Abstract: In this paper, the mechanical behavior of steel-concrete composite slim beams was investigated by experiments, and the influence of sectional dimension of steel beams on the bending stiffness and flexural capacity of composite slim beams was evaluated. Test results show that good cooperative performance can be achieved in steel-concrete composite slim beams and the relative slip between steel and concrete is very small. The steel-concrete slim beam presents considerable deformation ability beyond the service stage, which indicates that the composite slim beam has good ductility. In addition, sectional dimension of steel beams is proved to have significant influence on both the bending stiffness and flexural capacity of composite slim beams.

Abstract: In the process of natural energy depletion, foamy oil is characterized of low production Gas Oil Ratio, high oil viscosity, high daily production rate and high primary recovery factor. The stability of the foam turns out to be the prevailing factor that governs the life of the ‘foamy oil’. To enumerate the main factors affecting the stability of the foam, a high-temperature–high-pressure visualized experiment model for foamy oil stability test was developed. A serial of experiments was conducted to evaluate the performance of the foam stability. The effects of oil viscosity, height of the oil column, dissolved gas content and dispersed gas were investigated and recorded. These experiments were conducted using a Hele-Shaw, a high pressure cell. The volume of foamy oil produced, either by a step reduction in pressure or by a gradual (linear) reduction in pressure, and its subsequent decay was observed, visually. The experimental results show that foamy oil stability increases with higher oil viscosity, higher oil column, higher dissolved gas content and higher pressure decline rate. Asphaltene content was not observed to increase the foamy oil stability significantly. The results also show that the foam quality of foamy oils is much lower than aqueous foams.

Abstract: Shelter, the second basic need of man, has been a preoccupation for many governments all over the world trying to house their growing population. Roof is the covering on the uppermost part of a building. Roof not only provides protection to the buildings from the effects of weather but also plays an important role in architectural and aesthetic point of view. Profiled steel sheet are increasingly used in structural application in recent years. Profiled steel sheet connected to plywood which is known as profiled steel sheeting plywood (PSSPW) system can be used as an alternative to traditional form of roof construction. This study investigated experimentally and analytically the possibility of employing the PSSPW as a roof surface to provide an efficient emergency shelter. The aim of this study to investigate the structural strength and behaviour of composite profiled steel sheet with plywood. The tests were performed on profiled steel sheet and profiled steel sheeting with plywood. The failure loads, failure modes and the load-web deformation behaviour of profiled steel sheeting with plywood are also presented. The experimental and analytical results were compared to validate and determine the structural strength and behavior of profiled steel sheet and composite profiled steel sheet with plywood (PSSPW). This PSSPW composite roofing helps to enhancing the stiffness and strength of the composite system. The proposed PSSPW composite roofing system has a great potential to be exploited for the construction of housing as well as disaster relief shelter. The application of plywood as a load bearing structural component in PSSPW system has the potential to meet the demands of building construction. This system can reduce time and overall cost of construction and has the potential of opening up new composite system in the building construction industry.

Abstract: Standard decentralized ventilation systems typically consist of two ventilators for inlet and exhaust air and a heat exchanger for the heat recovery. A recently developed device, a so called friction ventilator, combines these three elements into a single functional element. The ventilator consists of circular plates which are rotating centrally in between the inlet and the outlet duct of a ventilation system and generate a countercurrent flow in the two ducts. Furthermore, the discs act as a rotating heat exchanger between the two air flows. To increase understanding of the energy transfer from the rotating discs to the flow an experimental investigation on the effect of different rotor geometries was conducted. The study showed an interesting influence of the hub diameter on the characteristic curves with a higher pressure difference for an increase in diameter. The results of the heat recovery measurement however were only mildly affected by the hub geometry. Here the distance between the discs, the rotational speed of the discs and the volumetric flow seemed to have the greatest effect on heat recovery.

Abstract: Earthquakes are the most unpredictable damaging loads which can affect civil engineering structures. Due to insufficient separation distance between adjacent structures with different dynamic properties, structural collisions may occur during ground motions. Although the research on structural pounding has recently been much advanced, the studies have mainly been conducted for concrete structures. The aim of this paper is to show the results of experimental investigation, focused on dynamic behaviour of closely-separated three models of steel structures which have been subjected to damaging earthquake excitations. The study was performed using three models of steel towers with different dynamic parameters and various distances between the structures. The acceleration time histories of the Kobe and the Northridge earthquakes were applied as the seismic excitation. The unidirectional shaking table, located at the Gdansk University of Technology (Poland), was used in the experimental study. The results have confirmed that collisions may lead to the increase in the structural response, although they may also play a positive role, depending on the size of the separation gap between the structures.

Abstract: The impact of cutting speeds and feed rates on the components of the forces exerted on a 16MnCr5 steel workpiece is experimentally measured, when turning with PCBN tool. The cutting speed range of the tests varies between 90 to 240 m/min while the feed rate is between 0.05 and 0.25 mm/rev for each cutting speed, allowing for the determination of the influence of cutting conditions on forces. Additionally, finite elements models for the simulation of the aforementioned experiments are provided. The proposed models exhibit good correlation of their results on cutting forces and chip formation with the measurements and observations of the experiments. Furthermore, the models can provide a wide range of additional parameters, i.e. plastic strain rates and temperatures within the workpiece. Results of the presented analysis can be used for an efficient process planning for the turning of steels under cutting conditions used in the industry.

Abstract: This paper presents the results of an experimental research aiming to investigate on the compressive behavior of full size clay brick masonry columns reinforced with Basalt Fiber Reinforced Cementitious Matrix (BFRCM) or with steel wires collaring. Uniaxial compressive tests were performed on eight retrofitted columns and four control specimens. Two masonry strength were considered by varying the mortar grade. Results are presented and discussed in terms of axial stress-strain relationships, failure modes and crack patterns of the specimens tested up to failure. For the limit of investigated variables, comparisons with unreinforced specimens show the ability of these alternative techniques in increasing ductility with limited strength enhancements, even if further investigations should be addressed on detail effectiveness and scale effect.