Flexible Fiber Fabric for FRP–Concrete Connection of Thin Hybrid Slabs

In order to combat corrosion issues, several studies on progressively replacing steel reinforcement elements with composite ones have been conducted in recent years. Hybrid steel–concrete thin slabs in which the steel acts as formwork are also candidates for update in the coming years. Achieving a reliable connection between fiber-reinforced polymer (FRP) and cast-in-place concrete is key to promoting this technology. This study analyzed different connection systems and proposes the novel approach of embedding a flexible fiber fabric as a superficially distributed connector between concrete and FRP. Eight specimens with four different connection strategies were tested using an experimental modal analysis and a quasi-static three-point bending test. The impact of the connection system on the vibrational response, flexural ultimate load, moment response, neutral axis position, shear and dissipated energy was obtained and compared. The results show that the use of an embedded mesh increases the frictional mechanism and produces the best performance in terms of load-bearing capacity and ductility.

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Assessment of Sandwich Beam in Three-Point Bending for Measuring Adhesive Shear Modulus

Journal of Engineering Materials and Technology ◽

10.1115/1.1375159 ◽

2001 ◽

Vol 123 (3) ◽

pp. 322-328 ◽

Cited By ~ 8

Author(s):

Jianmei He ◽

Martin Y. M. Chiang ◽

Donald L. Hunston

Keyword(s):

Shear Modulus ◽

Sandwich Beam ◽

Adhesive Layer ◽

Test Method ◽

Bending Test ◽

Beam Specimen ◽

Element Analysis ◽

Three Point Bending ◽

The Impact ◽

Made In

A finite element analysis (FEA) was conducted to examine the feasibility of determining the shear modulus of an adhesive in a bonded geometry using a three-point bending test on a sandwich beam specimen. The FEA results were compared with the predictions from two analytical solutions for the geometry used to determine the impact of the assumptions that were made in these analyses. The analytical results showed significantly different to the values obtained from other experiments on bulk samples of the adhesive in the glassy region. Although there were some agreements in rubbery region, the negligible sensitivity of the beam stiffness to the presence of adhesive layer makes the agreements very questionable. To examine the possible explanations for these differences in glassy adhesives, sensitivity analysis was conducted to explore the effects of experimental variables. Some possible reasons for the differences are discussed, but none of these reasons taken alone satisfactorily account for the discrepancies. Until an explanation is found, the three-point bending test using a sandwich beam specimen to determine the adhesive shear modulus might not be a desirable test method, at least for the range of geometry examined in this study.

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Development of the impact resistance for the composite limb protectors via three point bending test of lamb metacarpus

Current Opinion in Biotechnology ◽

10.1016/j.copbio.2013.05.045 ◽

2013 ◽

Vol 24 ◽

pp. S29

Author(s):

Ibrahim Kutay Yilmazcoban ◽

Ahmet Cagatay Cilingir ◽

Yasar Kahraman ◽

Sedat Iric ◽

Cetin Karakaya

Keyword(s):

Impact Resistance ◽

Bending Test ◽

Three Point Bending ◽

The Impact

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Bending Behavior of Lightweight Wood-Based Sandwich Beams with Auxetic Cellular Core

Polymers ◽

10.3390/polym12081723 ◽

2020 ◽

Vol 12 (8) ◽

pp. 1723 ◽

Cited By ~ 1

Author(s):

Krzysztof Peliński ◽

Jerzy Smardzewski

Keyword(s):

Mechanical Properties ◽

Experimental Studies ◽

Numerical Calculations ◽

Bending Test ◽

Dissipated Energy ◽

Sandwich Beams ◽

Wood Composites ◽

Three Point Bending ◽

Good Ability ◽

Bending Behavior

The work concerns a three-point bending test of beams made of plywood, high density fibre boards, cardboard, and wood-epoxy mass. The goal of the investigation was to determine the effect of thickness and type of wood-based facings on stiffness, strength, ability to absorb, and dissipate the energy of sandwich beams with an auxetic core. The cognitive goal of the work was to demonstrate the possibility of using recycled materials for facings and cores instead of popular wood composites. Experimental studies and numerical calculations were performed on correctly calibrated models. Experimental studies have shown that the beams with HDF facings (E = 1528 MPa, MOR = 12.61 MPa) and plywood facings (E = 1248–1395 MPa, MOR = 8.34–10.40 MPa) have the most favourable mechanical properties. Beams with plywood facings also have a good ability to absorb energy (1.380–1.746 J), but, in this respect, the beams manufactured of HDF (2.223 J) exhibited better capacity. The use of an auxetic core and facings of plywood and cardboard significantly reduces the amount of dissipated energy (0.0093 J, 0.0067 J). Therefore, this type of structures can be used for modeling beams carrying high deflections.

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Effect of Deflection Rate on Bending Deformation Behavior of Fe-Based Shape Memory Alloy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.566.116 ◽

2014 ◽

Vol 566 ◽

pp. 116-121

Author(s):

Keizo Nishikori ◽

Takeshi Iwamoto

Keyword(s):

Shape Memory ◽

Static Loading ◽

Deformation Behavior ◽

Rate Sensitivity ◽

Bending Test ◽

Bending Deformation ◽

Three Point Bending ◽

Positive Rate ◽

The Impact ◽

Deflection Rate

In this study, three-point bending test is conducted at various deformation rate by using a thin plate of Fe-based alloy. The rate sensitivity of its bending deformation during loading and shape memory effect by heating after unloading are investigated experimentally. The results obtained are summarized as bellows. (1) In the case where the quasi-static loading was applied, the positive rate sensitivity, which means the stress level increases with increasing the deflection rate, can be observed slightly. (2) It is hard to observe that recovery of deflection by SME depends on deflection rate under quasi-static loading. (3) In the case where the impact loading was applied, the positive rate sensitivity can be observed clearly.

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The Cooling Media Influence on Selected Mechanical Properties of Steel

Acta Technologica Agriculturae ◽

10.2478/ata-2020-0029 ◽

2020 ◽

Vol 23 (4) ◽

pp. 183-189

Author(s):

Radim Šmak ◽

Jiří Votava ◽

Adam Polcar

Keyword(s):

Mechanical Properties ◽

Plastic Deformation ◽

Cooling Capacity ◽

Structural Transformations ◽

Bending Test ◽

Metallic Materials ◽

Three Point Bending ◽

Cooling Medium ◽

Cooling Media ◽

The Impact

AbstractThe aim of experiment was to analyse the structural transformations and changes in mechanical properties of K720 steel during heat treatment (quenching). Three types of cooling medium were selected. The heating parameters and subsequent delays at the recrystallisation temperature were the same for all samples and were observed in a laboratory furnace. Water with the highest cooling capacity was selected as the benchmark cooling medium. Subsequently, the hardening oil TK – 46 was used. Sunflower oil was selected as the last quenching medium, which can be considered an ecological replacement of quenching oil with possibility of biological disposal. The microstructure and microhardness of individual samples were subjected to a metallographic evaluation and evaluated according to ČSN EN ISO 6507, respectively. The impact toughness analysis was performed according to the ČSN EN ISO 148-1 and a three-point bending test was performed according to ČSN EN ISO 7438. This test specifies a method for determining the ability of metallic materials to undergo plastic deformation in bending. The bend test includes subjection of round, square, rectangular or polygonal cross-section to plastic deformation by bending, without changing the direction of loading, until the specified angle of bend is reached.

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Effect of Nesfatin-1 on Rat Humerus Mechanical Properties under Quasi-Static and Impact Loading Conditions

Materials ◽

10.3390/ma15010333 ◽

2022 ◽

Vol 15 (1) ◽

pp. 333

Author(s):

Anna Skic ◽

Iwona Puzio ◽

Grzegorz Tymicki ◽

Paweł Kołodziej ◽

Marta Pawłowska-Olszewska ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Bone Structure ◽

Critical Energy ◽

Bending Test ◽

Ovariectomized Rats ◽

Loading Conditions ◽

Sem Images ◽

Three Point Bending ◽

The Impact

The investigations on the response of bone tissue under different loading conditions are important from clinical and engineering points of view. In this paper, the influence of nesfatin-1 administration on rat humerus mechanical properties was analyzed. The classical three-point bending and impact tests were carried out for three rat bone groups: control (SHO), the humerus of animals under the conditions of established osteopenia (OVX), and bones of rats receiving nesfatin-1 after ovariectomy (NES). The experiments proved that the bone strength parameters measured under various mechanical loading conditions increased after the nesfatin-1 administration. The OVX bones were most susceptible to deformation and had the smallest fracture toughness. The SEM images of humerus fracture surface in this group showed that ovariectomized rats had a much looser bone structure compared to the SHO and NES females. Loosening of the bone structure was also confirmed by the densitometric and qualitative EDS analysis, showing a decrease in the OVX bones’ mineral content. The samples of the NES group were characterized by the largest values of maximum force obtained under both quasi-static and impact conditions. The energies absorbed during the impact and the critical energy for fracture (from the three-point bending test) were similar for the SHO and NES groups. Statistically significant differences were observed between the mean Fi max values of all analyzed sample groups. The obtained results suggest that the impact test was more sensitive than the classical quasi-static three-point bending one. Hence, Fi max could be used as a parameter to predict bone fracture toughness.

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Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

Materials ◽

10.3390/ma14185133 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5133

Author(s):

Michele Meo ◽

Francesco Rizzo ◽

Mark Portus ◽

Fulvio Pinto

Keyword(s):

Impact Resistance ◽

Residual Energy ◽

Functionally Graded ◽

Low Velocity Impact ◽

Bending Test ◽

Three Point Bending ◽

Constant Pitch ◽

Biological Structures ◽

Post Impact ◽

The Impact

Composite laminated materials have been largely implemented in advanced applications due to the high tailorability of their mechanical performance and low weight. However, due to their low resistance against out-of-plane loading, they are prone to generate damage as a consequence of an impact event, leading to the loss of mechanical properties and eventually to the catastrophic failure of the entire structure. In order to overcome this issue, the high tailorability can be exploited to replicate complex biological structures that are naturally optimised to withstand extreme impact loading. Bioinspired helicoidal laminates have been already studied in-depth with good results; however, they have been manufactured by applying a constant pitch rotation between each consecutive ply. This is in contrast to that observed in biological structures where the pitch rotation is not constant along the thickness, but gradually increases from the outer shell to the inner core in order to optimise energy absorption and stress distribution. Based on this concept, Functionally Graded Pitch (FGP) laminated composites were designed and manufactured in order to improve the impact resistance relative to a benchmark laminate, exploiting the tough nature of helicoidal structures with variable rotation angles. To the authors’ knowledge, this is one of the first attempts to fully reproduce the helicoidal arrangement found in nature using a mathematically scaled form of the triangular sequence to define the lamination layup. Samples were subject to three-point bending and tested under Low Velocity Impact (LVI) conditions at 15 J and 25 J impact energies and ultrasonic testing was used to evaluate the damaged area. Flexural After Impact (FAI) tests were used to evaluate the post-impact residual energy to confirm the superior impact resistance offered by these bioinspired structures. Vast improvements in impact behaviour were observed in the FGP laminates over the benchmark, with an average reduction of 41% of the damaged area and an increase in post-impact residual energy of 111%. The absorbed energy was similarly reduced (−44%), and greater mechanical strength (+21%) and elastic energy capacity (+78%) were demonstrated in the three-point bending test.

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Static and dynamic response of sandwich beams with lattice and pantographic cores

Journal of Sandwich Structures & Materials ◽

10.1177/10996362211033896 ◽

2021 ◽

pp. 109963622110338

Author(s):

Yury Solyaev ◽

Arseniy Babaytsev ◽

Anastasia Ustenko ◽

Andrey Ripetskiy ◽

Alexander Volkov

Keyword(s):

Mechanical Performance ◽

Lattice Structure ◽

Unit Length ◽

Experimental Tests ◽

Plane Geometry ◽

Sandwich Beams ◽

Static Tests ◽

Three Point Bending ◽

The Core ◽

The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

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Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽

10.3390/ma14102690 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2690

Author(s):

Bo Pan ◽

Xuguang Wang ◽

Zhenyang Xu ◽

Lianjun Guo ◽

Xuesong Wang

Keyword(s):

Crack Initiation ◽

Crack Propagation ◽

Joint Angle ◽

Simulation Software ◽

Dissipated Energy ◽

Energy Structure ◽

Joint Angles ◽

Crack Penetration ◽

Before And After ◽

The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

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Additive Manufacturing-Based In Situ Consolidation of Continuous Carbon Fibre-Reinforced Polycarbonate

Materials ◽

10.3390/ma14092450 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2450

Author(s):

Andreas Borowski ◽

Christian Vogel ◽

Thomas Behnisch ◽

Vinzenz Geske ◽

Maik Gude ◽

...

Keyword(s):

Additive Manufacturing ◽

Carbon Fibre ◽

Bending Test ◽

Thermoplastic Composites ◽

Experimental Investigations ◽

Material Structure ◽

Three Point Bending ◽

Continuous Fibre ◽

Local Material

Continuous carbon fibre-reinforced thermoplastic composites have convincing anisotropic properties, which can be used to strengthen structural components in a local, variable and efficient way. In this study, an additive manufacturing (AM) process is introduced to fabricate in situ consolidated continuous fibre-reinforced polycarbonate. Specimens with three different nozzle temperatures were in situ consolidated and tested in a three-point bending test. Computed tomography (CT) is used for a detailed analysis of the local material structure and resulting material porosity, thus the results can be put into context with process parameters. In addition, a highly curved test structure was fabricated that demonstrates the limits of the process and dependent fibre strand folding behaviours. These experimental investigations present the potential and the challenges of additive manufacturing-based in situ consolidated continuous fibre-reinforced polycarbonate.

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