Papers by Keyword: Compression

Abstract: The paper investigates the influence of fibre orientation on the mechanical characteristics of PETG plastic products manufactured by FDM printing (Fused Deposition Modelling). Three groups of experimental samples were made with different fibre orientation: along the load axis, perpendicular to it, and at an angle of 45 °. Experimental tensile and compression tests, including the stages of elastic deformation, structure strengthening, and local fracture, were performed to study the mechanical characteristics of the material. It is established that the orientation of the fibres is a determining factor of strength and deformation behaviour of products: samples with fibres along the load axis are characterized by increased plasticity and strength, while the transverse orientation reduces mechanical resistance due to interlayer destruction. Samples with fibre orientation at an angle of 45° demonstrated an optimal combination of strength and deformation capacity. The results of the study confirm the need to consider the fibre orientation when designing PETG plastic products to ensure optimal performance.

Abstract: This study explores the potential of self-healing concrete with bacteria encapsulated in calcium lactate and expanded clay (LECA) to enhance the durability and strength of concrete structures. The effect of encapsulating Lysinibacillus sphaericus bacteria in LECA on the mechanical properties of concrete was investigated, including compressive and tensile strength. Calcium lactate acts as a precursor and nutrient source for the biomineralization process through Microbially Induced Calcium Carbonate Precipitation (MICP). Experimental results demonstrate that concrete with bacteria encapsulated in LECA exhibits a significant increase in compressive strength compared to conventional concrete and concrete containing non-encapsulated bacteria. This increase is attributed to the protection provided by LECA to the bacteria and calcium lactate, promoting their self-healing activity and improving the concrete's ability to withstand loads. An increase in compressive load was observed for design DR-5 compared to DR-0 (control), with increments of 3.40%, 0.21%, and 6.92% on days 7, 14, and 28, respectively. However, challenges were identified regarding tensile strength, as design DR-5 was initially lower than design DR-0 by 24.25% and 19.51% on days 7 and 14, respectively. Nonetheless, on day 28, design DR-5 surpassed the control design by 1.45%. This study concludes that the encapsulation of bacteria in LECA, along with calcium lactate as a nutrient source, is a promising strategy for enhancing the performance of self-healing concrete, opening new avenues for research and applications in sustainable construction.

Abstract: Emergency conditions are situations that can happen to anyone, anywhere and anytime. An emergency is a life-threatening condition in an emergency, such as cardiac arrest, resulting in a sudden loss of blood flow due to failure of the heart to pump effectively, which can lead to death. The key factor in increasing the number of survivors is the quality of cardiopulmonary resuscitation (CPR). Quality of CPR is indicated by a chest compression frequency of 100 - 120 beats/minute and a depth of 5mm, with a minimum lag time. Cardiac pump resuscitation (CPR), which provides circulatory and respiratory support, is a common therapy applied to almost all cardiac or respiratory arrest cases. Compression and ventilation are effective measures of cardiac pump resuscitation (CPR). This research refers to the system, design, and manufacture, including the chassis and assembling of the control system manually and automatically. Controlling the equipment using Arduino Uno, motor driver, and dimmer to manually and automatically adjust or control the compression speed manually and automatically. The results showed that the greater the applied voltage, the greater the compression. The increase occurred from 109, 112, and up to 119 compressions per minute manually, while automatic increases occurred from 110, 113, and up to 119 compressions per minute and with a compression depth of 40 mm

Abstract: The determination of drying period, compressive strength, and air-dry density represent crucial parameters for assessing the quality and performance of earthen construction materials. This paper explores the possibilities of using the ultrasonic method as a non-destructive testing technique applied to earthen materials (specimens, elements, or structures) to determine these properties. The method relies on the measurement of ultrasonic pulse velocity (UPV), which is influenced by factors such as density, elasticity, and curing process. By analyzing the propagation of ultrasonic waves through earthen samples, valuable insights can be gained regarding their drying period, compressive strength, and density. The drying period of earthen samples can be determined using the ultrasonic method by monitoring the changes in pulse velocity over time. As the moisture content decreases during the drying process, the velocity of ultrasonic waves increases due to the reduced presence of water. This allows for the estimation of the drying period without the need for time-consuming and destructive testing methods. Compressive strength is also a critical parameter in assessing the structural integrity of earthen materials. The UPV method offers a non-destructive approach to determine the compressive strength of earthen samples. This provides a valuable tool for quality control and assessment of earthen construction materials. Density is another important property that influences their performance and the UPV method can be used to determine the density of earthen materials by measuring the ultrasonic pulse velocity and analyzing its relationship with density. This non-destructive approach allows for quick and efficient estimation of the compactness and quality of earthen mixes. Overall, the ultrasonic method offers a non-destructive and efficient approach in determining the drying period, compressive strength, and density of various soil compositions. By measuring the pulse velocity and analyzing its relationship with these properties, valuable insights can be gained regarding the quality and performance of earthen construction materials. This method has the potential to significantly improve the assessment and quality control processes in earthen construction, leading to more sustainable and reliable structures associated with the earthen techniques.

Abstract: Due to the complex compression failure process of fiber composite materials, especially the direct bearing situation of the composite material end face, it is quite difficult to accurately predict it. At present, the design of composite material compression performance mainly considers a large safety factor, and a compression failure assessment method that can meet the needs of reliable engineering applications is still a challenge and a key issue that the engineering community urgently needs to solve. This article reviews the widely studied shear type buckling model, extensional type buckling model, matrix strain failure theoretical model, matrix shear failure theoretical model, interlayer shear failure theoretical model, elastic micro buckling model, plastic micro buckling model, three parameter model, fiber microbuckling finite element model and ply mesobuckling finite element model of fiber reinforced composite materials that have been publicly published in recent years, which were analyzed and summarized, providing reference for further in-depth research in the future.

Abstract: The strain rate exerts a profound influence on the mechanical characteristics of nanomaterials. To investigate this phenomenon, the molecular dynamics approach was employed to examine the impact of uniaxial compression along the [100] crystallographic direction in monocrystalline Al. The purpose of this research was to determine the differences in reactions observed during the elastic and plastic phases. It employed the Embedded Atom Method (EAM) as well as the Modified Embedded Atom Method (MEAM) potentials at 300 K. A comparative analysis of the outcomes from these potentials demonstrated considerable disparities. The results encompassed the percentage distribution of crystal structures (fcc, hcp, bcc, and others) as well as their atomic configurations. Several analytical factors were examined, including the strain-stress curve, the radial distribution function (RDF), the common neighbor analysis (CAN). The applied MEAM potential represents a subsequent occurrence of transitions following EAM, encompassing both increasing and decreasing phase transitions.

Abstract: In power transmission systems, gears are the most essential parts. Gear failure would happen at any regular working cycles and it must be avoided with special care. The mode of failure suggests that optimum material and suitable post processing has to be done. Industry demands more efficient, reliable, and lightweight gears. Hence more efficient, reliable, and lightweight gears must be developed and manufactured. Eventhough lot of investment is being done on research and implementing new technologies while manufacturing gears, stills some failures is arised. Many physical factors, including the inappropriate materials composition, may induce gear failure. In this paper, some typical diverse materials, like nylon 6 and glass fibers are mixed with various volume proportions to enhance wear resistance and improve gear’s life. Polymer gears developed in this study offer more superior life than pure nylon gears. All the prepared specimen samples are tested to a variety of studies including Tensile, Compression, Flexural, Impact, TGA and Wear tests. Depreciation is not reducing low, however. 90% nylon 6 + 10 % Glass fiber to 10% nylon 6+ 90Glass fiber 10 % Nylon 6 has mixed for investigation. Based on the investigation, 70% of Nylon 6 + 30% glass fiber has high strength, low wear, and high wear resistance.

Abstract: Self-propagating intermediate temperature synthesis (SIS) is a process that utilizes exothermic reactions to initiate and maintain component combustion so as to produce low porosity values and high hardness. It is necessary to know about the heat transfer phenomenon because SIS has a weakness, namely the high exothermic rate and very fast combustion rate which requires a high level of control. In addition, compression or compaction needs to be done because this method is expected to produce a homogeneous particle density distribution. The phenomenon of heat transfer and pressure that occurs in the SIS process is a simplification of the self-propagating high-temperature synthesis (SHS) process, which can be simulated and analyzed using engineering software based on finite element analysis. Stress simulation that occurs with the addition of weight percent titanium 5%, 10% and 20% using a pressure of 171 MPa and produces a normal stress. The heat transfer simulation that occurs uses a temperature of 750 ^°C, 850 °C, and 950 °C with a processing time of 2 hours with variations in the addition of weight percent titanium 5%, 10%, and 20% which results in an effect on heat flux and temperature distribution. Samples that were given the addition of 20% titanium by weight were given a pressure of 171 MPa to produce a normal stress of-230.44 MPa with the lowest porosity value of 22.63%. Samples processed at 850 °C with the addition of 10% weight percent titanium produced the lowest heat flux value of 0.0027220 W/m².

Abstract: Heating and cooling activities of buildings consume a considerable amount of energy used in building envelopes and are responsible for almost 16 % of CO2 emissions in the air. This problem has been confronted with a recent worldwide trend by introducing eco-friendly buildings with net zero emissions. Currently used thermal insulators in building envelopes are usually made from synthetic polymers which are difficult to recycle or dispose of. This paper presents a novel bio-composite mats using Egyptian pulled wool fiber waste and flax fibers waste as an alternative to commercial polystyrene foam. High loft nonwoven mats with different blends of wool and flax are fabricated and characterized to utilize a composite structure with satisfactory thermal and physical properties. Thermal conductivity test, ignition test, and compression and recovery test are applied to the developed specimens. The results proved the competitiveness and suitability of the proposed composites to be used as building interior insulators when compared to polystyrene and other similar composite materials from literature.

Abstract: Plastic waste is an ever-growing concern, causing harm to many ecological and human health aspects, one of the major contributors to this problem being packaging. Mycelium composites (MC) are ecologically safe materials, well suited for the short-life usage as packaging materials. In our study we made MC using fine and coarse granulometry hemp shives applying them in 3 substrate variants – with added bran, with added bran and birch bark, and as the sole substrate. We assessed material's water absorption and mechanical properties, chemical decomposition, biodegradability, mold resistance and fungal biomass. Granulometric effect was observed only when using shives as the sole substrate, where larger particle size gave poorer results. Bran did not significantly improve mechanical properties or water uptake. Bark reduced water uptake by ~200 %, but lowered mechanical properties, and provided no benefits to mold resistance which was low for all specimens. Overall, hemp MC showed complete biodegradability after 12 weeks, mechanical properties up to 0,235 MPa, compatible with expanded polystyrene, but very high water uptake of up to 1000 %. Future studies are needed to reduce water absorption and improve mold resistance, as well as invent consensus methodology for better cross-study comparison.