Flexural Impact Research Articles

Utilisation of Plastifying and Fluxing Wastes of Plastics and Eggshell Powder in Manufacture of Eco-Friendly Floor Tiles

This study addresses the possibility of utilizing polypropylene plastics and eggshell wastes in the manufacture of eco-friendly floor tiles. Therefore, the research is part of the ongoing hunt for establishing sustainable alternatives for disposing off plastic and eggshell wastes around the globe. In this study polypropylene plastic wastes (PPW) are melted and used as a binder to eggshell powder (ESP) acting as a flux in the matrix. These are combined with fine aggregates. Three ternary mixes of PPW-ESP-Sand are made in the proportions of 50–0–50%, 55–10–35%, and 60–20–20%. Thirty six sample tiles of size 250 mm x 250 mm x 8 mm are cast. The physical properties of PPW, ESP, and sand are first established. Then, the effect of this PPW and ESP on the flexural strength, impact resistance, density, and water absorption of floor tiles made are investigated. Specifically, the bulk density of PPW, ESP and sand were 370, 1280, and 1700 Kg/m3 and specific gravities were 0.93, 2.54, and 2.64 respectively. Meanwhile, PPW–ESP–Sand mix of 60-20-20% had the lowest water absorption at 0.15% and also the lowest density of 1570Kg/m3, and the highest modulus of rupture of 11.7kN/mm2 compared to conventional ceramic tile at 3.9KN/mm2. The tile manufactured from the mix of 60-20-20% also exhibited the highest resistance to impact damage although all samples had a coefficient of restitution (e=0). In conclusion, the study presents a novel finding of combining two wastes replacing conventional non-renewable resources of clay and feldspar to produce eco-friendly tiles. Therefore, implementing the findings will facilitate achieving United Nations sustainable development goals (SDG), i.e. goal 12 of responsible consumption and production.

Experimental and numerical investigation on the impact response of CFRP under 3-point-bending

The strain rate-dependent material characteristic of carbon fiber reinforced plastics (CFRP) is widely known and has been investigated in detail at coupon level. In this study, for the first time the strain rate dependent characteristic of a three-dimensional CFRP structure was investigated. The evolution of the determined strain rate dependency was correlated with the results at coupon level. For this purpose two special 3-point-bending fixtures were developed to obtain the flexural impact response of the investigated T700S DT120 prepreg system at coupon and component (hat profile) level. The rectangular coupon specimens were loaded with quasi-static to intermediate impact velocities from 3.3×10−5 to 10m s−1, while the structural sub components were tested using impact velocities from 3.3×10−5 to 1m s−1. With increasing impact velocities, the experimental tests showed a significant increase in force at first failure and maximum deflection at coupon level. The increases in force were of 52% and 120%, respectively. However, the increase for structural hat profile components was just 12.4% due to a different failure mode. The observed initial failure modes were compressive failure provoked by fiber kinking for the coupon and interlaminar shear failure for the structural component. Regardless of the different failure modes this work proves the necessity of considering the strain rate dependency of a composite material to accurately predict the maximum load capacity of a CFRP structure during a dynamic load event. Additionally, the comparison of the experimental results restults to numerical results revealed weaknesses in the prediction accuracy of the currently used models.

Impact performance of novel multi-layered prepacked aggregate fibrous composites under compression and bending

Multi-layered Prepacked aggregate fibrous composite (MLPAFC) is a new type of concrete, which is prepared in two subsequent stages of aggregate-fibre skeleton prepacking and cementitious grouting. In this study, ten MLPAFC mixtures were prepared in three subsequent layers incorporating different contents of four different types of steel fibres. Long and short hooked-end and crimped steel fibers were adopted with 3.0 and 1.5% dosages for the outer and interior layers, respectively. In-between the three MLPAFC layers, two layers of Glass Fiber Mesh (GFM) were inserted in five of the ten mixtures. The impact response of the MLPAFC mixtures was evaluated using two test methods. In the first, the ACI 544-2R repeated free-falling weight test was followed using disk specimens, while flexural free-falling weight on prism specimens was the second adopted impact test. Moreover, Weibull distribution was used to statistically analyse the discrepancies of the obtained experimental impact records. The impact tests results revealed that MLPAFC can absorb significantly high energy under falling weight impact due to its structure and the dual crack arresting activity of both steel fibers and GFM. The cracking number of impacts of MLPAFC cylindrical specimens without GFM was increased by approximately 530–870% compared reference specimens, while increment percentages reaching 1350% were recorded at failure stage. The impact resistance of MLPAFC prisms under flexural impact was noticeably improved, yet with lower percentages than cylindrical specimens. The insertion of intermediate GFMs let to additional developments in the impact strength of both cylindrical and prism specimens.

Flexural impact response and damage detection of composite sandwich beam with various PVC foam cores

This article investigates the flexural impact and damage behavior of composite sandwich beam in terms of foam core effect using the micro-computerized tomography, Micro-CT. Foam core is dominant on the damage behavior of sandwich structures. As the python scripting language was used parametric modeling, the intra-laminar damage was created with the three-dimensional explicit finite element subroutine and implemented to ABAQUS as VUMAT via FORTRAN. The results of the FEM were found to agree well with experimental observations. Notably, the change in foam core density has a very high effect on contact force levels, impact trend and damage progress.

Flexural impact response and energy absorption characteristics of textile reinforced mortar

The present paper investigates the characteristics of textile reinforced mortar (TRM) beams under flexural impact. The key test parameters focuses on determining the effect of the two types of textile material namely glass and basalt, number of textile layers and positioning of textile layers. TRM beams were experimentally evaluated under different energy levels with respect to the load specification. Effect of single and repeated impact was examined on standard TRM specimens. The results showed that in the case of glass and basalt textile, the optimum number of textile layers is different in order to achieve maximum impact resistance. The peak energy level for TRM with glass textiles is found to be higher than that of TRM with basalt textiles for optimal reinforcement. The energy absorption for glass TRM for single impact is higher than basalt TRM and the same is substantially reduced when subjected to repeated impact compared to basalt TRM. The crack pattern and failure mode are found to be more dependent on the number of textile layers.

Impact behaviour of nanomodified deflection-hardening fibre-reinforced concretes

The behaviour of concrete under sudden impact loads is complex. Moreover, very little is known about the impact behaviour of high-performance fibre-reinforced concretes (HPFRCs). To account for this, nanomodified deflection-hardening HPFRC mixtures incorporating coarse aggregates were produced with three ratios of fly ash to Portland cement (0·0, 0·2 and 0·4), three nanomaterials (nanosilica, nano-alumina and nanocalcite) and two hybridised fibre combinations (hooked-end steel with polyvinyl alcohol, or hooked-end steel with brass-coated microsteel) and tested for basic mechanical properties and flexural impact resistance. After experimental testing, beams used in impact testing were modelled using Abaqus. Cubic compressive strength did not change significantly with the differences in mixture parameters, although this was not the case for flexural parameters. For a given fly ash/Portland cement ratio and nanomaterial type, mixtures with hooked-end steel and polyvinyl alcohol fibres exhibited higher displacement and lower flexural strength capacity than those with hooked-end steel and brass-coated microsteel fibres. Nano-alumina contributed best to the development of mechanical properties and impact resistance of HPFRCs, followed by nanosilica and nanocalcite. Results validate the idea that costly polyvinyl alcohol fibres can be fully replaced with brass-coated microsteel fibres without risking mechanical properties and impact resistance, as long as matrix properties are properly controlled.

Preparation and Study of Flexural Strength and Impact Strength for Hybrid Composite Materials used in Structural Applications

Many of the polymeric materials used for structural purposes have weak mechanical properties, these characteristics can therefore be improved by preparing a hybrid laminar composite. In this work use melting mixing method using screw extruder to prepare sheets of polymer blends and nanocomposites based on polymer blends, and using a hot hydraulic press machine to prepared hybrid laminates composites. Two groups of hybrid laminar composites were prepared, the first group is consist of [((94%PP: 5%PMMA: 1 %( PP-g-MA)): 0.3% ZrO2): 6%KF and 8%KF] and the second group is [((94%PP: 5%UHMWPE: 1 %( PP-g-MA)): 0.3% ZrO2): 6%KF and 8%KF]. The results illustrated the impact strength and fracture toughness are increase with increased weight percentage of Kevlar fiber in for both groups of laminar composites and the highest values for two groups are (58.1, 54.95 KJ/M2) and (8.4, 9.16 MPa√m) respectively, any that, at the rate of increment reached to (120.4%, 107%) and (52.7%, 66.5%) respectively, compared with the neat PP. Moreover, the flexural strength values of the first group samples of hybrid laminar composite remained constant, when added kevlar fiber to nanocomposite. While, the flexural strength values of the second group samples of hybrid laminar composite increase with increase the ratio of kevlar fiber in composite to reach the maximum values (92 MPa) at 8% wt. of kevlar fiber, any, at the rate of increment reached to 39.4% compared with the neat PP. As well as, the results shown that the flexural properties and fracture toughness of the second group samples higher than they are for the first group samples.

An effective finite element modeling approach for prediction of the behaviour of a jute fibre-reinforced composite tube under axial impact

The focus of the work reported here is on the prediction of the behaviour of a hollow cylindrical jute– polyester composite tube under axial impact using the explicit finite element analysis code, LS-DYNA. An efficient finite element modelling approach using a single shell element through the thickness of a thin-walled structural part has been chosen. Effective orthotropic material properties of a laminate which can be determined through standard ASTM tests have been used as input data for a popular constitutive model titled ‘Enhanced Composite Damage’ with the option of specifying either the Chang–Chang criteria or the Tsai–Wu criterion for failure. A unique feature of the current approach is to verify the modeling procedure initially for coupon-level tensile, compressive and flexural tests through a numerical design of experiments involving a set of physically meaningful fibre and matrix failure strain parameters, and then extend the same toward successfully predicting the mechanical behaviour of a jute composite tube subject to axial drop-weight impact. Theoretical predictions of peak responses for flexural and tube impact tests are also presented.

Mechanical Properties of Concrete Using Treated Recycled Concrete Aggregate in Marine Environment

This study also investigates the effectiveness of multiple surface modification of recycled concrete aggregate (RCA) with respect to mechanical properties of the resultant recycled aggregate concrete (RAC) when exposed to various curing conditions, namely, normal water (Nw) and seawater (Sw). The properties included compressive and flexural strength and impact resistance. Findings show that effect inclusion of the treated coarse RCA is significant in enhancing the mechanical properties of RAC. The exposure to Sw appears to affect the degradation of the compressive strength of RAC remarkably in a marine environment. In this case, however, using of treated RCA is found beneficial in decreasing the deterioration in the compressive strength of RAC.

Mechanical Properties of Hierarchical Biopolymer Composite with a Modified Surface of Knitting Fabric

The paper deals with the evaluation of mechanical properties of a biopolymer biodegradable composite obtained by injection molding (InMold technology) of knitted hierarchical fabric in the injection mold. Two methods of modifying natural fibers of the hierarchical fabric were used to influence adhesion at the interface between the polymer and the knitted fabric. The first type of modification was acetylation and the second type was the use of physical treatment using low temperature plasma, atmospheric dielectric barrier discharge (DBD). The polymer composite matrix was PLA polymer from NatureWorks LLC. The structural fabric was a weft interlock knitted fabric in three different geometric characteristics made from natural cotton yarn. Experimental measuring on evaluation of mechanical properties, tensile, flexural and charpy impact tests were performed on prepared samples not only for different types of modifications of natural fibers of knitted fabric, but also in terms of orientation of knitted fabric in a biopolymer composite system.

High-Temperature Cermet Material Based on Intermetallic Nickel Matrix

A method for synthesis of an intermetallic nickel matrix reinforced with particles of different refractory compounds added at different concentrations is considered. Prepared materials are based on two variants of a Ni3Al–Cr–W–Mo–Ti–Hf alloy: type VKNA-1V alloy and type VKNA-1V alloy with increased tungsten content (VKNA-1V(W)). The intermetallic matrix is reinforced with nanoparticles of the oxides Al2O3, Al2O3 ⋅ Y2O3, and Al2O3 ⋅ Y2O3 ⋅ HfO2, with the content of reinforcing component at 2 and 5 vol %. Samples are compacted by spark plasma sintering. The microstructure of prepared cermet materials (CMs) is investigated using scanning electron microscopy. The impact viscosity and flexural strength are determined. We establish the effect that the content and composition of the reinforcing component has on the physicomechanical properties of the high-temperature CMs based on an intermetallic matrix dispersion-hardened with refractory metal particles. Our findings show that the optimal combination of flexural strength and impact viscosity at room temperature is achieved in the CM sample in which the intermetallic matrix is based on VKNA-1V(W) alloy and the reinforcing component is represented by ternary oxide Al2O3 ⋅ Y2O3 ⋅ HfO2 added at a concentration of 2%.

Abrasion Resistance, Flexural Toughness and Impact Resistance of Rubberized Concrete

This study aimed to investigate abrasion resistance, flexural toughness and impact resistance of concrete mixes with incorporated particles of crumb rubber (CR) as a partial substituent by volume to concrete natural aggregates. Seven concrete mixes were prepared with water to cement ratio 0.4 and cement content 450 kg/m3 . One mix, with no rubber content, was considered as a reference mix to compare the designated mechanical properties of plain rubberized mixes, while the remaining six mixes contained crumb rubber as a partial replacer at levels of 10%, 20% and 30% by volume of each sand and crushed stone aggregates. Abrasion resistance was evaluated according to British standard BS 1338 and impact resistance was measured according to ACI 544.2R. It has been discovered that increasing CR replacement level led to a significant improvement in abrasion resistance, flexural toughness, and impact resistance (number of blows that cause failure cracking). Abrasion lengths decreased by 3.0 - 20.6%, while flexural toughness and impact resistance increased by 8.2 - 39.4% and 18.7 - 365.4% respectively with increasing crumb rubber replacement level.

Efectos de los limpiadores de prótesis dentalessobre las propiedades del material: Un estudio observacional de casos y controles

Everyday use of denture cleansers to prevent microbial colonization on dentures can affect the properties of the denture base material. Limited literature is available on the effects of denture cleanser on reinforced resins. This study aimed to evaluate and compare the effect of denture cleanser on the flexural and impact strength of conventional and reinforced heat cure acrylic resins. Materials and Methods: Rectangular shaped specimens were prepared for flexural and impact strength as per ISO 1567. The denture base resins used included conventional, high impact, nylon fiber reinforced and glass fiber reinforced heat cure acrylic resins. They were further categorized into subgroups A and B depending on immersion in distilled water or denture cleanser (3.8% sodium perborate based). The flexural strength and impact strength of specimens were measured. The study design is a observational case-control study. SPSS version 25 statistical analysis software was used, and the STROBE statement checklist was followed. Results: The mean flexural strength was highest for glass fiber reinforced heat cure resin followed by conventional heat cure resin, high impact heat cure resin and nylon reinforced heat cure resin, respectively. The mean impact strength was highest for high impact heat cure resin followed by glass fiber reinforced heat cure resin, conventional heat cure resin, and nylon fiber-reinforced resin respectively.Conclusion: All the denture base resins tested exhibited a decrease in flexural and impact strength following use of a denture cleanser.

Preparation, Performance Test, and Microstructure of Composite Modified Reinforced Concrete

To investigate whether the compound modification means which mixes modified Polyvinyl chloride (PVC) aggregate and polypropylene fiber in concrete could gain “positive hybrid effect” and cope with more sophisticated engineering circumstances, four groups of test specimens were prepared: concrete doped with unmodified PVC aggregate, concrete doped with modified PVC aggregate, concrete doped with unmodified PVC aggregate and polypropylene fiber, and concrete doped with modified PVC aggregate and polypropylene fiber. The fiber content is 0.9 kg/m3, the modified solution content is 1 mol/L NaOH, and the replacement amount of PVC fine aggregate in replacement sand is 0%, 5%, 10%, 20%, and 30%. Mechanical property and durability tests were carried out to compare and analyze the measured compressive strength, splitting tensile strength, flexural tensile strength, water absorption rate, and impact failure energy. Moreover, scanning electron microscopy and XRD diffraction were used to analyze micromorphology and crystal structure of concrete. The test results demonstrate that as the content of PVC aggregate increases, the compressive strength, splitting tensile strength, and flexural tensile strength of the concrete decrease significantly, while the brittleness is improved. Meanwhile, the water absorption rate increases and the impact resistance shows an approximately linear increase trend. Under the same content of PVC aggregate, the most effective way to improve compressive strength is to use modified PVC aggregate. The rapid decrease of compressive strength caused by PVC aggregate can be effectively delayed by doping polypropylene fiber and modified PVC aggregate. Adding polypropylene fiber or using the modified PVC aggregate can improve the brittleness, tensile strength, flexural tensile strength, and impact resistance, but they have different modification and reinforcement effects. The concrete prepared by doping polypropylene fiber and modified PVC aggregate has better performance in tensile strength, flexural tensile strength, brittleness, and impact resistance, and the water absorption and the compressive strength of the concrete are enhanced compared with the normal group. Therefore, composite modified reinforced concrete doped with modified PVC aggregate‐polypropylene fiber has broad application prospects.

Effect of Acid Activation-Hydrophilic-Modified Sepiolite on Comprehensive Properties of Oil-Well Cement

In this paper, sepiolite was treated by acid activation, coupling agent treatment, and sulfonation modification. The purpose of this study was to explore the changes in the fluidity and mechanical properties of sepiolite cement slurry before and after modification. Therefore, the comprehensive properties of unmodified sepiolite fiber (HPS) and acid activation-coupling agent treatment-sulfonated sepiolite fiber (S-O-H-HPS) in oil-well cement slurry were evaluated. FT-IR and microscopic mechanism of cement paste fracture surface before and after sepiolite modification were analyzed. The results showed that HPS can effectively improve the toughness of cement paste, but when the content of HPS was more than 1%, the fluidity of cement paste deteriorated sharply and the compressive strength decreased gradually. The addition of S-O-H-HPS can significantly improve the fluidity and stability of HPS slurry. Without affecting the compressive strength, it can effectively improve the flexural strength and impact strength and reduce the elastic modulus of cement paste. The mechanism analysis showed that S-O-H-HPS can not only form network structure in cement paste but also improve the toughness of cement paste by forming a bridge. This also explains why the strength of S-O-H-HPS cement paste does not decrease significantly with the increase of S-O-H-HPS.

The influence of boot longitudinal flexural stiffness on external mechanical work and running economy during skate roller-skiing: A case study

This case study examines the impact of boot longitudinal flexural stiffness on the total external mechanical work of a skier’s centre of mass per distance travelled in the forward direction ([Formula: see text] EX (J/m)) and on running economy during skate roller-skiing under submaximal steady-state conditions. Moreover, it analyses time derivatives of total W EX, of W EX performed by the roller-skis and poles, respectively, and of the directly useful mechanical work (the sum of the work to overcome centre of mass’ gravity and rolling resistance) within a typical roller-skiing cycle. Multiple roller-skiing trials (G3 technique) were performed by one subject on an inclined treadmill with boots of soft, intermediate, and stiff flexural stiffness. The orientation and magnitude of the roller-ski and pole ground reaction forces, body kinematics, VO2, and lactic acid concentration were monitored. The stiff boots had 13.4% ( p < 0.01) lower [Formula: see text] EX compared to the intermediate boots, and 20.7% ( p < 0.001) lower [Formula: see text] EX compared to the soft boots. Regarding running economy, the soft boots had 2.2% ( p < 0.05) higher VO2 compared to the intermediate boots, but the same VO2 compared to the stiff boots. In conclusion, the soft boots had significantly higher [Formula: see text] EX and running economy, while stiff boots had significantly lower [Formula: see text] EX and intermediate boots significantly lower running economy. Moreover, [Formula: see text] EX appears to be a better indicator of the boot flexural stiffness impact on energy efficiency than running economy.

Effect of additives on shrinkage property of unsaturated polyester and mechanical properties of artificial stone

Artificial stone is composite of unsaturated polyester and calcium carbonate that is mostly synthesized. This study aimed to investigate the effect of additives on shrinkage property of Unsaturated Polyester (UP) and mechanical properties of artificial stone such as flexural strength, impact strength, and hardness. In this paper, we tested effect of additives such as anhydride maleic (AM), acrylonitrile butadiene styrene (ABS), methyl methacrylate (MMA) and polyvinyl acetate (PVAc) with varying concentrations from 1 – 10 phr under condition process includes 2 phr BPO, 1100C cured temperature and 20 mins cured time

Water absorption behaviour and its effect on the mechanical properties of Gigantochloa scortechinii (buluh simantan)

This study aims to investigate the effect of short-term exposure of water to the mechanical properties of simantan fibres at different heights. Few studies have investigated the mechanical properties of raw natural fibres after water absorption. Bamboo culms were cut at 15 cm above the ground level and then subdivided into bottom, middle and top parts according to their total length. The raw fibres were immersed in distilled water at room temperature for different time durations (6, 24, 48, 72, 96, 168, 336, 504 and 672 h). Tensile, flexural and impact properties were examined before and after water absorption, the tensile fracture of raw fibres were observed by scanning electron microscopy, and the structure properties of raw fibres were examined by Fourier transform-infrared spectroscopy. The result showed that 6 h of immersion time exhibited the best tensile strength and modulus, showing 13.6% and 28% improvement compared with the dry condition. The optimum flexural strength and modulus were 240 MPa and 13.7 GPa, respectively, for the top part under dry condition. Overall results clearly showed that immersion in water for a short time minimally affected tensile strength, modulus and flexural modulus but considerably influenced flexural strength and impact properties.

The Synergistic Effects of Multi-Filler Addition on the Mechanical and Thermo-Mechanical Properties of Phenolic Resins

The effects of the carbon fiber (CF), carbon black (CB) and nanosilica (SiO2) on the mechanical properties of the phenolic resin (PF) were studied and the optimum composition was selected for the preparation of quaternary composites (CF/CB/SiO2 phenolic composites). The incorporation of poly (acrylonitrile-co-butadiene) rubber (NBR) to strengthen the quaternary composites were also studied. The morphological, mechanical and thermo-mechanical properties of unmodified and NBR modified-quaternary phenolic composites were investigated. The phenolic compounds were mixed by ball milling and the phenolic composites were fabricated by hot compression molding. Scanning electron microscopy images of NBR modified-quaternary phenolic composites show the high fracture surface roughness. The results show that the addition of 5 wt% NBR in the quaternary composites offer the highest tensile strength and Young’s modulus which are significantly improved by 176% and 235%, respectively, and they also offer the high flexural strength, impact strength and flexural modulus which are improved by 79%, 29% and 12%, respectively, compared to neat PF. The glass transition temperature (Tg) of unmodified and NBR modified-quaternary phenolic composites are higher than that of neat PF (107.3 °C). The increase of NBR content does not deteriorate Tg of the quaternary phenolic composites. This study provides a new pathway for making advanced phenolic composites.

Low-Velocity Flexural Impact Analyses of Functionally Graded Sandwich Beams Using Finite Element Modeling

A comparative numerical investigation on low-velocity impact response of a metal/ ceramic functionally graded sandwich beam (FGSB) is performed by the commercial finite element (FE) software, LS-DYNA[Formula: see text]. The mechanical properties of the FG core are represented by a power-law depending on the volume fractions of the constituents. The effective elastic properties and elastoplastic behavior of the FG core are defined by Mori–Tanaka method and TTO (Tamura–Tomota–Ozawa) model, respectively. The effects of number of layers, compositional gradient, impact energy, and impact side are investigated. The simulation results indicated that both number of layers and compositional gradient have almost no effect on the kinetic energy history. In other respects, the compositional gradient exhibits a considerable effect, and the number of layers has a minor effect on the contact force history. Increasing impact energy does not have a considerable effect in terms of number of layers whereas it exhibits a significant effect in terms of compositional gradient on the percentage difference between the peak contact forces. Finally, the impact side does not influence the contact force history for all number of layers and compositional gradients.