This study aims to explore the effects of high-content rubber sand and steel fibers on the workability and mechanical properties of concrete, providing theoretical and data support for the resource utilization of waste tires and the engineering application of rubber sand concrete. Rubber particles replaced 60% of fine aggregates (by mass), and the volume fractions of steel fibers were set at 1.5%, 2.0%, 2.5%, and 3.0%. Ordinary concrete, rubber sand concrete, and rubber sand concrete with steel fibers were prepared, and slump, water absorption, compressive strength, and cyclic compressive performance experiments were conducted, along with microstructure analysis. The results show that the introduction of rubber slightly increased the slump of the concrete, but after adding steel fibers, the slump gradually decreased, with the most significant reduction when the steel fiber content reached 3.0%. Water absorption results indicate that rubber significantly increased the water absorption of concrete, and the increase in steel fiber content further exacerbated this trend. Compressive strength tests showed that the addition of rubber sand resulted in a 41.4% decrease in compressive strength, but an appropriate amount of steel fibers (2.0%) could significantly restore the compressive strength, with a recovery rate of up to 95.1%. However, when the fiber content exceeded 2.0%, strength decreased due to uneven fiber distribution and the aggregation effect. Cyclic compression performance studies showed that although the introduction of rubber enhanced the energy dissipation capacity of the concrete, it significantly reduced the load-bearing capacity, while the addition of steel fibers significantly improved the hysteretic energy dissipation and the damage resistance under cyclic loading, the sample with 2.5% steel fiber content exhibited the best performance. The distribution of rubber sand in the matrix weakened the interfacial bonding strength and increased the porosity, while the steel fibers significantly improved the concrete’s stiffness and damage resistance by bridging cracks and dispersing stress. When the steel fiber content was too high (2.5% and 3.0%), the aggregation effect of fibers weakened the uniformity of the matrix, leading to a performance decline. The results of this study provide a reference for the practical application of rubber concrete in pavement engineering.

Carbon fiber reinforced polymer (CFRP), known for their high strength, low density, and excellent corrosion resistance, are widely used in industries such as aerospace, automotive, and wind energy. In recent years, with the growing demand for lightweight solutions in the amusement ride industry, CFRP has gradually been used in non-primary load-bearing components. The lap bar, as a critical component used to secure passengers, has become a primary focus for lightweight design. This paper presents a preliminary study on failure analysis of a composite lap bar using acoustic emission (AE) and machine learning. The main purpose is to analyze the suitability of the prepared composite lap bar in a operational conditions using a classification model. The main challenge, however, is to be able to extract valid descriptors of the damage mechanism from the acquired AE signals. The damage modes of the basic units of the composite lap bar were first characterized individually and information of Hilbert marginal energy spectrum (HMES) about the AE signal associated with each damage mechanism was collected. These spectral features and parameters were then correlated and that is used as a dataset to train the model based on k-nearest neighbor (KNN) algorithm. The model achieved an accuracy of 92% through cross-validation. Then a destructive test was conducted on the composite lap bar, and the failure process was monitored using the AE technique. The acquired AE signals were identified by the classification model. This analysis provides information on the damage process of composite lap bar at different loading stages, with matrix cracking being the more common damage mechanisms. Additionally, the microanalysis of the fracture surface also verified the effectiveness of the classification model. Meanwhile, supervised machine learning shows its potential in handling multi-dimensional data.

Gaining an understanding of how chemical treatment affects the mechanical properties of natural fiber reinforced polymer composites is essential to enhance their performance and broaden their applicability across various engineering domains. The objective of this study was to develop bio-composites by combining polylactic acid with sisal fibers that have undergone chemical treatments and evaluating the mechanical properties at different temperatures to determine their suitability for high-temperature applications. For this purpose, sisal fibers were chemically treated using alkali, acetylation, and alkali/acetylation solution before composite processing. The results revealed that tensile strength slightly improved by alkali treatment, while both alkali/acetylation and acetylation treatments decreased the tensile strength and tensile modulus. Alkali treatment significantly enhanced flexural strength, while the effect of acetylation and alkali/acetylation treatments on flexural strength was less pronounced. All chemical treatments led to a slight increase in flexural strain at failure, but resulted in a decrease in tensile strain at failure and tensile modulus. Alkali treatment slightly increased flexural modulus, while acetylation and alkali/acetylation treatments significantly reduced it. The impact strength of the bio-composites was increased by alkali and acetylation treatments, but significantly reduced by alkali/acetylation treatment. Furthermore, the flexural strength of all bio-composites decreased as temperature increased, especially in plasticized bio-composites using tributyl 2-acetylcitrate plasticizer. The flexural strain at failure decreased with the addition of tributyl 2-acetylcitrate at room temperature. In plasticized bio-composites, the flexural strain at failure increased at 35°C, but decreased at 45°C. On the other hand, the flexural strain at failure of non-plasticized bio-composites remained constant up to 35°C, slightly increased up to 45°C, and then significantly increased at temperatures above 45°C. These bio-composites could be suitable for packaging industry as biodegradability is the criteria for such applications.

Ceramic membrane filters fabricated from local raw materials are excellent for municipal wastewater treatment. This paper studied the fabrication of ceramic membranes using Response Surface Methodology (RSM). It also looked at the influence of clay, palm kernel shell ash, kaolin, and starch on the properties of ceramic membrane filters. Optimal test conditions and procedures were determined by selecting a fitting model based on experimental data. The Box–Behnken design (BBD) was chosen for its ability to reduce the number of experimental trials, thus making it cost-effective. The BBD design was executed using Design-Expert 13 software (Stat-Ease, Inc., Minneapolis, MN, USA), requiring 29 experimental runs. According to the study, responses such as porosity, flow rate, thickness, and density were used in the model. The fabrication of the 29 ceramic membranes includes formulation, shaping (slip casting method), drying, and sintering. Based on RSM, an optimum ceramic membrane design was proposed: Kaolin = 413 g, Clay = 180 g, Starch 147 g, Palm Kernel shell ash = 13 g. Compared with the test results, this combination possesses favorable and reliable accuracy. The addition of kaolin played a role in creating a porous framework within the ceramic membrane. Clay serves as a binding agent, aiding the consolidation of ceramic particles within the membrane matrix. Starch served as a pore-forming agent during the fabrication process. From the study, the palm kernel shell ash served as a binder and a reinforcing agent, bolstering mechanical strength and structural robustness.

Digital image correlation (DIC) is a powerful technique for determining material deformation and damage and currently is viewed as a potential method to study failure and crack propagation in advanced composite materials. Case studies in concrete, epoxy adhesives, and carbon/epoxy laminates demonstrate the effectiveness of the DIC technique in visualizing crack propagation. This review highlights the applications, challenges, and implementation of the DIC technique in the failure and crack propagation of fibre-reinforced polymer (FRP) composites. The important factors such as field of view, speckle pattern, and algorithm choice are discussed while emphasizing the need for careful selection and calibration. The review concludes by highlighting the significance of crack propagation studies for composite behaviour and the role of DIC in calibrating and validating models of composite failure analysis. Future research directions include investigating mixed-mode delamination, improving calibration procedures, assessing DIC accuracy for large deformations, and comparing different DIC algorithms, which are discussed.

In order to enhance the fitness of the product and in order to improve productivity in turning operations, greater amount of challenges have been faced. In this paper, we have made a comparative analysis of HSS and carbide coated HSS drills while machining with H13 steel plates. For the drilling operation, process parameters were analysed using the Taguchi design of experiments. The response performance characteristics of surface roughness of H13 die steel plates for the drilling settings, cutting speed (rpm), and feed rate (mm/min) is optimized. The design of the experiment was conducted using the Taguchi technique for the L18 orthogonal array, and an analysis of variance was observed. The effect of drilling settings on the quality of drilled holes is examined; variation in surface roughness for various levels of speed and feed and the different combinations of these levels will form an L18 orthogonal array design of experiment by Taguchi analysis. A total of 36 cutting tests were performed with two different drill bits; here three different cutting speeds of 300, 600, and 900 rpm were taken with a feed rate of 0.02, 0.04, and 0.06 mm/rev combinations. The response of SN ratio for surface roughness of HSS and carbide tool has been found out for different levels of speed and feed. From this Taguchi analysis, it is identified that the optimal parameter. As a result, the factors are analysed, and optimized parameters have been concluded for H13 material using HSS, and carbide tools were examined both statistically and experimentally. The carbide coated drill bit gives 60% better surface roughness value based on experimental data obtained. The surface roughness value based on experimentation for HSS tool was found to be 34.16% and carbide coated drill bit was 23.40%.

The use and disposal of traditional fiber-reinforced polymer composites is an important environmental challenge as one of the factors contributing to worsening climate change. The primary objective of this research is to synthesize thermoplastic starch (TPS) from edible banana skins which can potentially be used as a matrix to produce bio-composite films. For the synthesis of TPS, the preparation of banana peels was performed followed by plasticization to obtain the banana peels TPS. For bio-composite film fabrication, the TPS was mixed with short false banana fibers (FBF) (10–30% by weight of the film) with an electronic blender to form a uniform dispersion of the fibers in the TPS. The FBF/TPS blend was applied uniformly on the surface of the rectangular metal mold. The autoclave method has been adopted for curing and molding the bio-composite film. Then, it was hot pressed varying the temperature and pressure from 131–141 OC to 3–6 MPa, respectively, to obtain the final cured film. The specimen was then solidified or hardened at ambient temperature. Finally, optimization of process parameters, fiber content, and their interaction effects on the tear strength, tensile strength, and bending modulus of the bio composite films were conducted using response surface methodology. The results indicate that both the effects of one factor and the interaction of factors have a significant effect on the mechanical properties of composite films. The optimum processing parameters for TPS production are a temperature of 50 OC and a drying time of 24 h. The optimal result indicates that, at 30% fiber loading, the optimum processing temperature and pressure are 135.14°C and 4.33 MPa, respectively, resulting in a composite film with good mechanical properties.

Composites with regenerated fiber bonded with natural fibers have attracted growing attention as the globe becomes more sustainable, ecofriendly, and environment-friendly. Pineapple leaf fiber is used for composite in this study since it is also handled as waste nowadays. Furthermore, viscose was chosen as a study variant since no one had ever tried a pineapple and viscose mixed composite before. Due to a scarcity of natural fiber production on Earth, regenerated cellulosic fiber reinforced with natural fiber is widely employed, providing a nearly identical experience by employing partial or less natural fiber. This paper describes a study that used pineapple leaf fiber mixed with a viscose composite and reinforced with epoxy resin. Pineapple viscose blended composite is composed of 1/1 plain wave design, and epoxy resin is applied on them to make stability by the compression molding process. The tested Tensile Strength (σ), Young’s Modulus, and Eb% are 20.7 Mpa, 579 Mpa, and 9.4%, respectively. Some testing is also carried out to differentiate the properties like bending strength 23.5 Mpa, bending modulus 717.6 Mpa, and avg. The pH of the composite is 9.54. This article has different analytical parts to acknowledge the actual condition of composite behaviors. Finally, some suggestions are made as to where it may be utilized and where appropriate to use it, such as on building sites, in Geotextile materials, Coffee cups, coffee cans, and agro-textile materials.

This paper presents experimental study on the response of a sustainable structure 3.65 x3.05x3.35 m, made with confined hollow concrete block masonry (CHCBM). The model was tested under quasi-static cyclic test to assess the response against seismic load and to determine the potential vulnerability. Based on test data, envelope curves and bilinear idealized curves were drawn according to both Magenes–Calvi and Elnashai methods. Different performance levels i.e. Immediate Occupancy (IO), Life Safety (LS) and Collapse Prevention (CP) were evaluated based on both methods. Damage pattern and force-deformation behavior of CHCBM building was compared with models of the similar configuration and loading conditions. Similarly values of Response modification factor (R), Displacement Ductility (µD) and Displacement amplification factor (Cd) were calculated and compared with the previously tested models and it confirmed that CHCBM building was ductile and structurally integrated under earthquake loading.

Bio-based materials have attracted ample research interest due to their intrinsic beneficial impact on human society. Microcrystalline cellulose (MCC) extracted from a variety of bioresources is one of the most prominent candidate in this regard. Herein, the MCC was synthesized from jute fiber by a facile ammonium persulfate (APS) oxidation method resulting in carboxylic functional groups on the fiber surface. The carboxylated MCC was utilized to develop polyvinyl alcohol (PVA) composite films in a solution casting method. The surface chemistry, thermal properties, and surface morphology of MCC and MCC-PVA composite films were studied by FT-IR spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The SEM images confirmed the rod-like MCC with average particle diameter 4.6 μm and length in 48.4 μm. The FT-IR spectroscopy suggested the complete removal of lignin and hemicellulose from jute fiber. A peak at 1730 cm−1 was introduced in MCC due to oxidation with APS. The MCC was readily dispersible in water, and chemical interaction with –OH group of PVA was spontaneous due to the carboxylation in MCC. The absorption peak of –OH groups in MCC-PVA composite films were shifted, somewhat disappeared and weakened due to the intra and intermolecular hydrogen bonding of MCC and OH groups in PVA. Thermogravimetric analysis expressed the thermal behavior of MCC and MCC-PVA composite films. The char formation at 500°C of the two different composite films was 15% and 16%, respectively. The stability of MCC-PVA composite films at elevated temperatures is the indication of potential application as flame retardant material.