Low-Velocity Impact and Post-Impact Residual Flexural Properties of Kevlar/EP Three-Dimensional Angle-Interlock Composites
Ontology highlight
ABSTRACT:
SUBMITTER:
PROVIDER: S-EPMC10856067 | biostudies-literature | 2024 Jan
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:In addition to manufacturing cost and production rates, damage resistance has become a major issue for the composites industry. Three-dimensional (3D) woven composites have superior through-thickness properties compared to two-dimensional (2D) laminates, for example, improved impact damage resistance, high interlaminar fracture toughness and reduced notch sensitivity. The performance of 3D woven preforms is dependent on the fabric architecture, which is determined by the binding pattern. For this study, angle interlock (AI) structures with through-thickness binding were manufactured. The AI cracking simulation shows that the transverse component is the one that leads to transverse matrix cracking in the weft yarn under tensile loading. Monitoring of acoustic emission (AE) during mechanical loading is an effective tool in the study of damage processes in glass fiber-reinforced composites. Tests were performed with piezoelectric sensors bonded on a tensile specimen acting as passive receivers of AE signals. An experimental data has been generated which was useful to validate the multi-physics finite element method (MP-FEM), providing insight into the damage behaviour of novel 3D AI glass fibre composites. MP-FEM and experimental data showed that transverse crack generated a predominant flexural mode A0 and also a less energetic extensional mode S0.
| S-EPMC5512521 | biostudies-other
Project description:The temperature-dependent mechanical behaviors of open-hole composite plates are essential for composite design and structures. Here, tensile experiments of shallow straight-link-shaped 2.5D woven composites (abbr. 2.5DWC) with/without a center hole are first conducted at different temperatures (20 °C, 180 °C and 240 °C). Failure modes are examined by scanning electron microscope (SEM). Thermal property of QY8911-IV resin is investigated by DMA analysis. It is noted for samples without the center hole that with the increase of temperature, the tensile stress-strain curves exhibit a linear response until that a slight nonlinearity at the end stage. The strength retention rates at 180 °C and 240 °C are totally equal. For the open-hole samples, it is interestingly found that the strength retention rates are higher than that of samples without the hole at 180 °C, resulting from the stress concentration accommodation and fiber-dominated failure mode. Even at 240 °C, there is no necking phenomenon for all the failed samples, but more broom-like damage extent is observed in the cross-section. Due to the primary load-bearing warp yarns and hole-edge stress concentration, obvious pull-out warp yarns emerge near the hole edge.
| S-EPMC7501272 | biostudies-literature
Project description:Bioinspired composites, capable of tailoring mechanical properties by the strategy of making full use of their advantages and bypassing their drawbacks, are vital for numerous engineering applications such as lightweight ultrahigh-strength, enhanced toughness, improved low-/high- velocity impact resistance, wave filtering, and energy harvesting. Helicoidal composites are examples of them. However, how to optimize the geometric structure to maximize the low-velocity impact resistance of helicoidal composites has been ignored, which is vital to the lightweight and high strength for aerospace, defense, ship, bridge, dam, vessel, and textile industries. Here, we combined experiments and numerical simulations to report the dynamic response of helicoidal composites subjected under low-velocity impact (0-10 m/s). Our helicoidal structures, inspired by the Stomatopod Dactyl club, are fabricated using polylactic acid (PLA) by FFF in a single-phase way. The helicoidal strategy aims to exploit, to a maximum extent, the axial tensile strength of filaments and simultaneously make up the shortage of inter-filament contact strength. We demonstrate experimentally that the low-velocity impact resistance has been enhanced efficiently as the helicoidal angle varies, and that the 15° helicoidal plate is better than others, which has also been confirmed by the numerical simulations. The findings reported here provide a new routine to design composites systems with enhanced impact resistance, offering a method to improve impact performance and expand the application of 3D printing.
| S-EPMC9002548 | biostudies-literature
Project description:The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure-thickness and entanglement-on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE) images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility.
| S-EPMC5459217 | biostudies-literature
Project description:PurposeTerminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design. The effects of the impact velocity (v0) and the impact attack angle (δ0) of the bullet on its terminal performance was investigated, using a new evaluation method (called expansion method) based on the expansion of cracks and the permanent cavity wall in ballistic gelatin.MethodsBallistic gelatin was used to simulate human body. The 7.62 mm × 39 mm rifle bullets with different v0 (600-760 m/s) and δ0 (0°-6°) were fired into the gelatin blocks. The gelatin block was cut into slices of about 20 mm thickness. The cracks and the permanent cavity on each slice were obtained manually. The damaged gelatin was determined using two methods: expanding the permanent cavity but ignoring the cracks, and expanding both the permanent cavity and the cracks. The relations between the damaged gelatin and v0 and δ0 were obtained using linear fitting method.ResultsAccording to the distribution of the damaged gelatin along the penetration depth, the damaged gelatin block could be divided into two parts: the less damaged part and the severely damaged part. The length of the less damaged part depends mostly on δ0; while the average damaged area of this part depends on both δ0 as well as v0. The cracks contributed significantly to the total volume of damaged gelatin, particularly when the expansion was larger than 1.9 mm. The total damaged gelatin increases with v0, δ0 and the expansion extent. The average length of equivalent cracks grew with v0 and δ0 when considering the cracks, and decreased with v0 when ignoring the cracks.ConclusionThe expansion method is suitable to investigate the influence of different factors of bullets on their terminal performance. The characteristics of the damaged gelatin have a linear relationship with the initial attack angle (δ0) and the initial velocity (v0) of the bullet.
| S-EPMC9252937 | biostudies-literature
Project description:Ferrocement is a cost-effective construction material used in the low-cost constructions. It is produced with the combination of cement mortar with closely spaced wire mesh known as chicken wire mesh. Ferrocement process eliminates coarse aggregates when compared to reinforced concrete thus makes the process simple. This paper deals with the influence of various characteristics of warp knitted fabric on the flexural properties of ferrocement composites. Ferrocement composites have a wide range of applications in the construction industry and it has some limitations due to the durability issues. Among the various durability issues, corrosion is one of the main issues to be addressed to enhance the long-term service life of the ferrocement composites. The idea of using non-metallic mesh to eliminate the corrosion problem is discussed in this paper. In this experiment, warp knitted fabric reinforced ferrocement composites were produced using polypropylene warp knitted fabrics. This paper deals with the flexural properties of ferrocement composites made of warp knitted fabric coated with expoxy. This paper deals with the flexural properties of ferrocement composites made of warp knitted fabric coated with expoxy. These composites were analyzed for their flexural strength, energy absorption and ductile property. The variables in the experiment are filament thickness, warp knitted structure and number of layers in the composites. Experimental results proved that the replacement of chicken mesh wire by warp knitted fabrics has an impact in the flexural properties of the composites and the effect of variables in the experiment set up has been analyzed. There is an imporvement of 200% is observed in the first crack load and 120% improvement in the ultimate load of the warp knit fabric reinforced composite compared to control sample. Experimental results proved that there is an increase in flexural strength of ferrocement composites made up with warp knitted fabrics. Microstructure studies like SEM and EDX on ferrocement laminates confirmed good bonding between the mortar mix and warp knitted fabrics.
| S-EPMC9572330 | biostudies-literature
Project description:ObjectiveThere is a substantial body of evidence that the recidivism of impaired-driving offenders is reduced while an ignition interlock device (IID) is on their vehicles. This study examines changes in driving behaviors and drinking behaviors used by DWI offenders to manage driving with the IID.MethodsA total of 166 IID participants who completed two surveys covering the period from arrest to IID installation (T1) and during IID use (T2) were examined. Four domains were covered: demographics, driving environments and transportation needs, reported driving activity, and reported drinking activities. Participants were on average 38 years old, 43% were female, 35% completed college, 34% had an income of more than $50,000, and 83% were employed. For those who provided it, the mean blood alcohol content (BAC) at arrest was .184 g/dL, with only 8 (5%) individuals below .08 g/dL, and 93 (56%) at over .18 g/dL. About 45% were repeat DWI offenders.ResultsBetween T1 and T2 there was a slight increase in acknowledging public transportation was available (p=.001), an increase in other individuals driving the interlock-equipped vehicle (p=.002), an increase in the number of vehicles in the household not registered to the DWI offender (p< .001), and an increase in the number of participants who reported that driving was important to their lifestyle (p=.008). Initial (T1) expectations about whether the interlock would be a problem were significantly different from actual experiences reported in T2 (p<.001). With respect to alcohol consumption, 14% reported abstinence at T2 compared to 2% at T1 (p=.001) and the number of drinks per drinking occasion decreased from a mean of 4.90 at T1 to 3.14 at T2 (p=.001), but the number of drinking occasions increased by a third (p=.003). The number of drinking locations (p=.001), the frequency of stopping after work for a drink (p=.001), and drinking at a bar all decreased (p<.001).ConclusionsInterlock users make some adjustments in how they drink, the amount they drink, and where they drink. This finding suggests that there may be methods that can be used to extend the benefits of the IID beyond the sanction period.
| S-EPMC7879393 | biostudies-literature
Project description:Mechanical properties of dental restorative materials are important for clinical success in prosthodontic care. However, open data on the mechanical properties of these materials are limited. This article provides data on the flexural strength and elastic modulus of dental composites in practical use for design/computer-aided manufacturing (CAD/CAM) systems. Eight brands of composites were subjected to deterioration tests: immersing in water at 37 °C for one day or seven days, or thermocycling (TC) in water at temperatures between 5 °C and 55 °C for 5000 or 10,000 cycles. The mechanical properties of the samples were measured by using a three-point bending test according to ISO 6872. The obtained values were statistically analyzed using one-way analysis of variance (ANOVA), followed by Tukey multiple comparison tests.
| S-EPMC6461697 | biostudies-literature
Project description:Despite the large number of studies addressing the effect of acrylic resin polymerization concerning flexural properties, limited research has been conducted on the manufacturing impact on a polymer's mechanical properties. Photosensitive resinous materials are used in various engineering applications where they may be exposed to multiple detrimental environments during their lifetime. Therefore, there is a need to understand the impact of an environment on the service life of resins. Thus, flexural tests were conducted to study the effects of exposure time and angle on the flexural strength of resins. Herein, the main objective was to explore the strength, stability, and flexural durability of photosensitive resin (EPIC-2000ST) fabricated at different exposure times (E) and angle deviation varying from 0° to 85° with a 5° increment. The samples in circular rings were manufactured and divided into five groups according to their exposure time (E): 10 s, 20 s, 30 s, 40 s, and 50 s. In each exposure time, we designed rings via SolidWorks software and experimentally fabricated at different oblique angles (OA) varying from 0° to 85° with a 5° increment during each fabrication, i.e., OA = 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, and 85°. Flexural strength was evaluated using a three-point bending test. Optical electron microscopy was used to examines the samples' exterior, interior, and ruptured surfaces. Our experimental analysis shows that flexural strength was significantly enhanced by increasing exposure time and at higher oblique angles. However, at lower angles and less exposure time, mechanical flexural resilience declines.
| S-EPMC9332362 | biostudies-literature
Project description:Aerogel fibers, the simultaneous embodiment of aerogel porous network and fiber slender geometry, have shown critical advantages over natural and synthetic fibers in thermal insulation. However, how to control the building block orientation degree of the resulting aerogel fibers during the dynamic sol-gel transition process to expand their functions for emerging applications is a great challenge. Herein, nanoscale Kevlar liquid crystal (NKLC) aerogel fibers with different building block orientation degrees have been fabricated from Kevlar nanofibers via liquid crystal spinning, dynamic sol-gel transition, freeze-drying, and cold plasma hydrophobilization in sequence. The resulting NKLC aerogel fibers demonstrate extremely high mechanical strength (41.0 MPa), excellent thermal insulation (0.037 W·m-1·K-1), and self-cleaning performance (with a water contact angle of 154°). The superhydrophobic NKLC aerogel fibers can cyclically transform between aerogel and gel states, while gel fibers involving different building block orientation degrees display distinguishable brightness under polarized light. Based on these performances, digital textiles woven or embroidered with high- and low-orientated NKLC aerogel fibers enable up to 6.0 Gb information encryption in one square meter and on-demand decryption. Therefore, it can be envisioned that the tuning of the building blocks' orientation degree will be an appropriate strategy to endow performance to the liquid crystal aerogel fibers for potential applications beyond thermal insulation.
| S-EPMC9527790 | biostudies-literature