Strength Of Strips Research Articles

Shear capacity prediction of carbon-fibre-reinforced polymer mesh fabric (CFRP-MF) stirrups reinforced concrete beams

Fibre-reinforced polymer mesh fabric (FRP-MF) is an effective substitute for normal steel stirrups in concrete to prevent steel corrosion in reinforced concrete (RC) structures. Nevertheless, methods for calculating the shear resistance of RC members rehabilitated in shear with FRP-MF configurations are lacking. Moreover, the methods for quantitative analysis of the shear contribution caused by the cracking control effect produced by CFRP-MF longitudinal FRP strips are unclear. In this paper, a mechanics-based segmental model is presented based on partial interaction analysis considering both transverse FRP strips and longitudinal reinforcements. By incorporating the carbon-fibre-reinforced polymer mesh fabric (CFRP-MF) stirrups into this model, a shear strength model was proposed and extended for design purposes in a closed form. In addition, the modified compression field theory (MCFT) model considering the shear strength of concrete in compression and the shear friction model (SFM) in the literature were appropriately modified and used for comparison with the segmental model. It should be noted that if the tensile strength of the longitudinal strips was added into the corresponding calculation formulas, it would cause the difference between the proposed novel models with the previous models. Finally, the shear strength of 14 CFRP-MF reinforced concrete beams were evaluated using these three models. The average ratios of the experimental values of the CFRP-MF RC beams to the shear capacity predicted by the modified segmental model, MCFT with the shear contribution of compressed concrete and SFM were 1.30, 1.19 and 1.19, respectively. It turns out that the modified mechanics-based segmental model yields the minimum discreteness based on the experiment results. This study can provide shear capacity calculation and design reference of RC beams with longitudinal FRP strip reinforcements for researchers and engineers.

Tunable bending characteristics of bamboo by regulating moisture content for bamboo curved component manufacturing

Traditional applications of mechanically robust bamboo are mostly confined to flat and straight components. Here, we investigated the tunable bending characteristics of bamboo strips by regulating the moisture content as a means to achieve efficient fabrication of single-layer and multi-layer bamboo curved components (SBCCs and MBCCs). Under the two opposite radial bending modes, the bending strength of bamboo strips decreased while their ductility and toughness increased as the moisture content increased from 0 % to 35 %, and the asymmetry of the bending properties became more pronounced. Moisture in bamboo strips was a double-edged sword for curved component manufacturing. Bamboo strips with high moisture content had higher bendability, which was conducive to improving the bending pass rate of SBCCs. At a bending radius of 70 mm, the total bending pass rate of SBCCs made from bamboo strips with 35 % moisture content was 85.9 % higher than that of SBCCs made from bamboo strips with 0 % moisture content. However, excessive moisture content could easily reduce the bending stability of the SBCCs and affect the bonding properties of the MBCCs. The optimal moisture content of bamboo strips for manufacturing curved components was 10–18 %, and increasing the moisture content of bamboo strips could produce components with complex shapes. The results can provide more possibilities for innovative bamboo product design and engineering applications, thereby promoting the utilization of sustainable and eco-friendly bamboo.

Rod models of strength of compressed concrete strips of the conjugation between beams and columns of prefabricated monolithic frames

Rod models of strength of compressed concrete strips of the conjugation between beams and columns of prefabricated monolithic frames

Experimental investigation on anchoring and bonding properties between Fe-SMA strip and concrete

In the technical system of the previous investigations, the prevalent method for external prestressed strengthening of concrete structures with iron-based shape memory alloy (Fe-SMA) strips is mechanical anchoring (without bonding). However, there is currently a lack of research on the adhesively bonded situation. In order to enhance the comprehension of the mechanical behavior of Fe-SMA/concrete joints, a total of 18 lap-shear test specimens were meticulously prepared, encompassing three distinct anchorage methods (single anchor-bolt anchorage, single-adhesive anchorage, and hybrid anchorage). The test series encompasses three varying bond lengths (300 mm, 350 mm, and 400 mm), three different activation temperatures (non-activated state, 200 ℃, and 300 ℃), as well as three diverse numbers of anchor bolts (1 bolt, 2 bolts, and 3 bolts). The bond-slip relationship before and after thermal activation was analyzed based on the data obtained from digital image correlation (DIC) tests. The results indicated that two or more anchors ensured strip rupture, exerting 40 % of its tensile strength. Single-adhesive bonding results highlighted the necessity for preventing debonding. The hybrid-anchorage method with anchor bolts and adhesive exerted 47 % strip strength and higher bond-slip stiffness. At 200 ℃ activation temperature, the interface rupture energy of the single-adhesive bonded specimen increased by approximately 30 %, but decreased by 22 % at 300 ℃. This paper provided an important reference for external prestressed strengthening of concrete structures with Fe-SMA strips under different situations.

A total rip-off—crack propagation in paper

The explanation of material properties starts at a young age identifying materials using words such as strong or brittle, but it is not until higher education that we teach how and why materials break along with what brittle really means. It is an important concept to understand, as a material that could be thought strong can be made to appear weak with the addition of a very small crack. As force is applied, these cracks, introduced through dents, scratches or even from the manufacturing process, can rapidly grow, leading to catastrophic failure. To help educators explain this concept in class without the need for specialised equipment or teaching complex theory, we present a set of accessible experiments on the fracture strength of paper strips. We show how the complexity of the experiment can be modified for various age groups, ranging from an engaging session for younger students pulling paper strips to a more involved extended practical using analytical solutions and fitting to determine the fracture strength of paper. These experiments have been delivered successfully to students of various ages and have led to stimulating discussions on the subject of materials science and engineering.

Decay resistance and dimensional stability of wood impregnated with castor oil using a pressure treatment

Abstract This study was conducted to investigate the uptake of castor oil (CAO) in some wood specimens and the effect of CAO on the leaching ability, dimensional stability and fungal-decay resistance of the wood specimens. CAO was infused into the specimens using a pressure treatment. Uptakes of CAO penetrated in yellow poplar (YEP), Japanese cedar (JAC) and Douglas fir (DOF) blocks were higher than 100 %. The leaching ability of the CAO-based suspensions against saline water was the lowest in YEP, followed by Japanese larch (LAR), JAC and DOF. The retention values were 90 % or higher in most of the specimens. Radial and tangential swellings of CAO-treated strips submerged in saline water for 2 weeks were restrained compared to control specimens. No significant differences were found between bending strength and Janka hardness of CAO-treated and control strips. CAO treatment provided acceptable decay resistance to most wood specimens against Fomitopsis palustris and Trametes versicolor. Retention of CAO in the leached strips were identified through X-ray microscopic observation. Based on the results, CAO was determined to be an effective agent for improving the dimensional stability of wood. These results demonstrate the great potential of CAO as an environmentally friendly wood preservative and dimensional stabilizer, allowing CAO-permeated wood as raw materials for both indoor and outdoor use.

Preparation and properties of copper-aluminum composite strips and foils by horizontal continuous composite casting and rolling

Cu-Al composite strips and foils show broad application prospects in electric power, new energy and other fields. However, they are difficult to prepare because of brittle interfacial intermetallic compounds and deformation ability difference between two matrix metals. In this study, Cu-Al composite strips and foils with the thickness of 350 µm and 50 µm are successfully prepared by horizontal continuous composite casting and rolling. Moreover, the effects of as-cast interfacial layer thickness on the properties of Cu-Al composite strips are studied. In the rolling, the as-cast interfacial layer is broken into fragments, so as to promote the Cu-Al matrix bonding at atomic scale. The local solid-state amorphous transformation is also observed at the newly formed Cu-Al interface. Therefore, with the as-cast interfacial layer thickness decreasing from 400 µm to 25 µm, the peeling strength of Cu-Al composite strips increasing from 15.1 N/mm to 17.5 N/mm. With the as-cast interfacial layer thickness decreasing from 400 µm to 65 µm, the conductivity of Cu-Al composite strips increases from 62.36%IACS to 72.58%IACS because the size of interfacial layer fragments is reduced. However, with the as-cast interfacial layer thickness decreasing from 65 µm to 25 µm, the conductivity decreases from 72.58%IACS to 68.65%IACS because the copper layer thickness after rolling is reduced. Large interfacial layer fragments hinder current conduction, but a suitable interfacial layer thickness can inhibit the coordinated deformation of Cu and Al, so as to increase the proportion of copper layer thickness in the entire composite strip.

Collaboratively enhancing the strength and ductility of GH3600 Nickel-Based Ultra-Thin strips via the Pre-Precipitation process

Here, the effects of pre-precipitation annealing on the microstructural evolution and room-temperature mechanical properties of nickel-based ultra-thin strips after the subsequent high-temperature annealing were analyzed. By pre-precipitation annealing, discontinuous grain-boundary carbide was introduced into the cold-rolled 67 μm GH3600 nickel-based ultra-thin strips, which hindered the rapid migration of grain boundaries. Thus, the grain size was maintained at only 5.5 μm after holding at 1050 °C for 1 h, indicating that the high-temperature microstructure stability of the strips was significantly improved. Further, the phenomenon of local single-layer crystal and size effect caused by the abnormal coarsened grains, which were more than 100 μm in size during the single-stage high-temperature annealing (1050 °C for 1 h), was eliminated. Owing to the weakened free surface influence and an increase in the strengthening effect, such as grain boundary strengthening, as well as intragranular and intergranular back stress strengthening, the work hardening ability of the strips was enhanced after pre-precipitation annealing, thereby resulting in excellent comprehensive mechanical properties whose flow stress and elongation were 1.9 and 4.8 times those of single-stage high-temperature annealing. This study successfully provides an economical and easy-to-implement effective method to prepare solid-solution-strengthened high-performance ultra-thin superalloy strips.

Optimum conditions for the biodegradation of waste low-density polyethylene strips by bacteria isolated from parts of north central Nigeria

Optimum conditions (Temperature, pH and incubation time) were studied for selected bacterial isolates Pseudomonas aeruginosa1(PA1), Pseudomonas aeruginosa2 (PA2), Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris to biodegrade low-density polyethylene (LDPE) waste by using Basal Salts Medium (BSM) containing 0.500g LDPE strips (1 cm by 5 cm each) using changes in mechanical properties and weight loss of the strips as indicators for ability of these microorganisms to degrade LDPE. The results revealed that four of the eight bacterial isolates, Pseudomonas aeruginosa1, Pseudomonas aeruginosa2, Bacillus megaterium, and Providencia stuarti showed high ability to degrade the LDPE strips after 8 weeks of incubation in liquid Basal Salts Medium at pH 6.5 -7.5 and 32oC. The tensile strength of the LDPE strips was reduced by 0.047±0.41 MN/M2 (47%) for P. aeruginosa1, 0.040±0.30 MN/M2 (40%) for P. aeruginosa2, Bacillus megaterium, 0.033±0.61 MN/M2 (33%), and Providencia stuarti, 0.027±0.41 MN/M2 (27%). The weight loss of the LDPE recorded for Pseudomonas aeruginosa1 was 19.80±0.04 %, for Pseudomonas aeruginosa2 19.40±0.08 %, 13.40±0.10 %, for Bacillus megaterium and 19.20±0.42 % for Providencia stuarti respectively. There was significant difference in the weight loss of the LDPE strips at pH 6.5 for Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis and Enterobacter hormaechei and at 30-32 oC for Pseudomonas spp., Bacillus megaterium, Klebsiella pneumonia and Proteus vulgaris(P>0.05 %).

Bonding Properties of AA1050 Strips Fabricated Via Electrically Assisted Roll Bonding (EARB) Process

Abstract In this study, aluminium alloy 1050 strips were bonded together using the electrically assisted roll bonding process (EARB) at electric current levels from 0 A up to 300 A. The effect of electric current level and plastic strain as the two main EARB parameters have been investigated on bonding strength by using the peel test. Results showed that by increasing the electric current level and reduction in thickness, stronger bonding strength can be obtained. Scanning electron microscopy was utilized to characterize the peeled surfaces of samples versus different thickness reduction ratios and electric current levels. Decreasing the forming strength of strips and increasing the bond strength of bonded strips about three times due to Joule heating effect in the EARB process was achieved. Moreover, by scanning electron microscopy (SEM), the peeled surfaces of samples after the peel test have been studied to investigate the bonding quality.

Experimental study on anchorage and activation performance of Fe-SMA strips for structural reinforcements

Iron-based shape memory alloy (Fe-SMA), taking advantage of its unique shape memory effect, is increasingly used to strengthen and rehabilitate deficient or deteriorated structures. The connection and activation methods are considered as the key techniques for the application of Fe-SMA. In this work, the China-made Fe-SMA strips were used and the material characteristics at room and elevated temperatures were examined. Two types of mechanical anchorages were designed to connect Fe-SMA strips with steel beam. A simple setup was designed to evaluate the performance of anchorages. Fe-SMA strips were heated by a low-cost activation method with hot gun. The temperature transfer law and recovery stress of Fe-SMA strips during activation were monitored during experiment. The test results indicated the mechanical anchorages showed good performance and the strength of Fe-SMA strips at failure was over 85% of its ultimate strength. The influence of activation decreases rapidly with the increase of distance from heating area, and the elevated temperature did not cause thermal damage on the reinforced structure. A theoretical equation was proposed based on the temperature transfer law to predict temperature of each point on Fe-SMA strips, which could be employed in determining the bonding length of adhesive bonding joint for Fe-SMA reinforcement in practice.

A new strategy for bamboo ultra-long radial slice preparation and novel composite fabrication

Bamboo has high-mechanical-strength fibers arranged longitudinally in its growth direction. However, its hollow structure has nodes and uneven density walls, which complicate bamboo processing and utilization. In this study, a method for preparing bamboo ultra-long radial slices (BURSs) along the bamboo growth direction and using the corollary equipment was proposed. New BURSs with a curling shape were collected regularly and weighed to be approximately the same. Several groups of BURSs with the same quality were regularly arranged and pressed into BURS composites (BURSCs) with density of 0.5, 0.6, 0.7 or 0.8 g/cm3. The BURSs well retained fiber integrity. The BURSC with density of 0.7 g/cm3 showed a higher strength-to-density ratio (S: D) than wooden oriented strand board (OSB). Its modulus of rupture, modulus of elasticity, internal bond strength and thickness swelling were 47.5 MPa, 3723 MPa, 1.03 MPa and 3.61%, respectively. Furthermore, a novel BURS processing mode which was optimized into bamboo medial slices with thin edge and green strips with triangular cross-section was proposed. Drum-shaped cross-section with thinner edge improved flowability of bamboo slices during hot pressing and optimized the structure of the composites. This BURS was a novel high-quality component of bamboo boards with high surface quality, strip strength, efficient producing and easy assembling of bamboo strands. The BURSC was proved to be an upgrade product of bamboo OSB and bamboo plywood with high S: D, excellent surface quality and high utilization rate of bamboo.

Effects of equal channel angular rolling process on the mechanical properties of Al-Cu two-layer sheets: experimental and numerical approaches

Abstract This study investigates the mechanical properties and microstructural characteristics of explosion-welded Al/Cu two-layer strips during the ECAR process using finite element simulations and experiments. Furthermore, the explosion-welded Al/Cu two-layer strip was examined with various configurations to determine the effects of die angle and friction coefficient on the distributions of effective strain and stress. In addition, the experimental and computational approaches were utilized to explore the ECAR process in two routes, RA and RC, for three directions. Finite element simulations were run and validated using experimental data. The findings show that the ECAR method is effective to enhance the mechanical characteristics of the strips. Moreover, the obtained results represent that the ECAR process reduced the size of the grains. Furthermore, it was shown that by increasing the number of routes in the ECAR process, the stress values were increased. However, the ductility of the two-layer strip was decreased. According to the current study, the route and the number of routes used in the ECAR process have a considerable effect on the strength of the two-layer strip.

An attractive attempt: Facile and direct adhesive of cellulose substrates using inorganic metal salt through partial welding

The development of cellulose-substrate remedies remains a technological challenge owe to their inability to self-heal and excessive dependence on petroleum-based adhesives, which is further hindered by the significant drawbacks of commercially unavailable welding materials and inconvenient manipulation. We herein describe a cellulose-substrate bonding technique achieved through partial dissolution using a low dosage of ZnCl2 aqueous solvent (ZS) and its dissolved cellulose (ZDC) gel as adhesives. This method demonstrates strong joint areas between strips without any failure, while shrinkage in the diffusion area remains the main cause of breakage. This shrinkage phenomenon can be alleviated by using ZDC instead of ZS, due to the water retention of hydrophilic hydroxyls on the macromolecular chains of dissolved cellulose. The well-maintained tensile strength of the ZDC-bonded strip (5.0% lower than the control) indicates that partially dissolved cellulose fills gaps between fibers, providing evidence for a mechanical interlocking adhesive mechanism in strip connections. ZDC gels exhibit favorable adhesive behavior for hand-sheets, art paper, and corrugated board, with welded joints demonstrating robust mechanical performance even after soaking in water for 6 h.

Estimation of the Ultimate Strength of FRP Strips-to-Masonry Substrates Bond

Fiber-Reinforced Polymers (FRP) were developed as a new method over the past decades due to their many beneficial mechanical properties, and they are commonly applied to strengthen masonry structures. In this paper, the Artificial Neural Network (ANN), K-fold Cross-Validation (KFCV) technique, Multivariate Adaptive Regression Spline (MARS) method, and M5 Model Tree (M5MT) method were utilized to predict the ultimate strength of FRP strips applied on masonry substrates. The results obtained via ANN, KFCV, MARS, and M5MT were compared with the existing models. The results clearly indicate that the considered approaches have better efficiency and higher precision compared to the models available in the literature. The correlation coefficient values for the considered models (i.e., ANN, KFCV, MARS, and M5MT) are promising results, with up to 99% reliability.

Seismic performance of steel staggered truss frame equipped with brace-type hybrid dampers with multiple nonlinear stages

This paper explores the effectiveness of a brace-type hybrid damper (BTHD) to enhance the seismic performance of a steel staggered truss frame. The study commenced by overcoming the severe abrasion of the friction component in the previous study and improving the hysteretic behaviour of the BTHD. An improved solution using BTHD was proposed and examined via numerical analysis. Stable friction behaviour played an important role in the multi-stage hysteretic energy dissipation characteristics. A simplified model composed of the friction behaviour, plasticity behaviour, and stopper mechanism was created in ABAQUS. The results were compared to a detailed finite element (FE) model and good accuracies were achieved. Parameter studies were conducted to investigate the influence of the length of the slotted hole, friction force, and yielding strength of the steel strips. To demonstrate the effectiveness of the BTHD, a conventional steel staggered truss frame (SSTF) was designed and built. The idea of SSTF composed of BTHDs (i.e. hybrid damper-SSTF) was designed and built simultaneously. The two structures had the same initial stiffness and ultimate strength. The cyclic pushover analysis and nonlinear dynamic analysis revealed that the deformation pattern of the structure was controlled, and the formation of a weak storey was thus prevented.

Study on Manufacturing Technology of Ultra-Thin/Narrow Bonding Cu Strip for Electronic Packaging

The performance of rolling parameters and annealing processes on the microstructure and properties of Cu strip were studied by High Precision Rolling Mill, FIB, SEM, Strength Tester, and Resistivity Tester. The results show that with the increase of the reduction rate, coarse grains in the bonding Cu strip are gradually broken and refined, and the grains are flattened when the reduction rate is 80%. The tensile strength increased from 248.0 MPa to 425.5 MPa, while the elongation decreased from 8.50% to 0.91%. The growth of lattice defects and grain boundary density results in an approximately linear increase in resistivity. With the increase of annealing temperature to 400 °C, the Cu strip recovers, and the strength decreased from 456.66 MPa to 220.36 MPa while the elongation rose from 1.09% to 24.73%. The tensile strength and elongation decreased to 192.2 MPa and 20.68%, respectively, when the annealing temperature was 550 °C. The trend of yield strength of the Cu strip was basically the same as that of tensile strength. The resistivity of the Cu strip decreased rapidly during a 200~300 °C annealing temperature, then the trend slowed, and the minimum resistivity was 3.60 × 10−8 Ω·m. The optimum tension range annealing was 6–8 g; less or more than that will affect the quality of the Cu strip.

THEORETICAL AND EXPERIMENTAL STUDY OF THE ROLL BONDING BEHAVIOR OF BILAYERS AL LAMINATES

In recent years, bimetallic strips have been progressively used in manufacturing to make collective purposes. Amongst cladding approaches, the rolling process is one of the most popular processes in making bimetallic strips. In this study, a new analytical model based on the slab method has been proposed to predict the bond strength of two layer strips. Results show that the bond strength of strips increases with increasing total rolling thickness reduction of the samples. Also, the finite element simulation and an experimental study were run to approve the results obtained from the new analytical model for producing AA1060/AA7075 bimetallic strips. Moreover, the planned analytical model is appropriate for modeling the roll bonding process of the two-layer strips and it is proficient to extend our information in engineering and production of bimetal strips. The bonding strength of bilayer samples enhanced by increasing the reduction in thickness ratio. The peeled surface of samples has been investigated using scanning electron microscopy (SEM).

Tensile properties and failure mechanism of enhanced carbon nanotube/epoxy resin composite strips

AbstractCarbon nanotube strips (CNTSs) can be used as preforms for developing high performance nanocomposites. Herein, CNT/epoxy resin (EP) composite strips with different orientations and densities were prepared by three structural treatment methods including infiltrating EP into CNTS, stretching, and pressing. Their tensile properties and failure mechanisms were analyzed. Stretching and pressing induced rearrangement of CNTs and proper resin infiltration could increase load transfer between CNTs within CNTS. Tensile strength of composite strips prepared under stretching and pressing was nine times higher than that of pristine CNTSs. Failure mechanism shifted from massive bundles pullout to brittle fracture due to polymer sticking.

Femtosecond Laser Cutting of 110-550 µm Thickness Borosilicate Glass in Ambient Air and Water.

The cutting quality and strength of strips cut with femtosecond-duration pulses were investigated for different thicknesses of borosilicate glass plates. The laser pulse duration was 350 fs, and cutting was performed in two environments: ambient air and water. When cutting in water, a thin flowing layer of water was formed at the front surface of the glass plate by spraying water mist next to a laser ablation zone. The energy of pulses greatly exceeded the critical self-focusing threshold in water, creating conditions favorable for laser beam filament formation. Laser cutting parameters were individually optimized for different glass thicknesses (110-550 µm). The results revealed that laser cutting of borosilicate glass in water is favorable for thicker glass (300-550 µm) thanks to higher cutting quality, higher effective cutting speed, and characteristic strength. On the other hand, cutting ultrathin glass plates (110 µm thickness) demonstrated almost identical performance and cutting quality results in both environments. In this paper, we studied cut-edge defect widths, cut-sidewall roughness, cutting throughput, characteristic strength, and band-like damage formed at the back surface of laser-cut glass strips.