Fiber Elements Research Articles

Effects of Different Additives and Ratios on Broom Sorghum Straw Silage Characteristics and Bacterial Communities

As a large agricultural country, China produces a large number of agricultural and sideline products while harvesting agricultural products every year. Crop straw is one of them. Broom sorghum is a traditional crop in China, which produces a large amount of straw resources every year. These straw resources are placed in the field and cannot be used efficiently. The purpose of this study was to solve the problem of straw utilization of Broom sorghum, one of the main food crops in arid and semi-arid areas of northern China. Broom sorghum is not only a nutritious food crop, its straw is also rich in crude fiber and mineral elements, which has high utilization value. However, due to the high content of lignocellulose in straw, the texture is hard, which limits its digestion and utilization efficiency as feed. In this study, the broom sorghum straw was used as the research object, and the straw raw materials were treated with Lactobacillus plantarum, cellulase and xylanase, respectively. After silage fermentation for 30 d and 60 d, the bags were opened to determine the nutritional quality, fermentation quality, microbial community structure and other indicators. The best fermentation time and additives for broom sorghum straw silage were comprehensively screened to improve the nutritional value of straw and animal production performance. The results showed that the nutritional quality of silage straw increased with the extension of fermentation time. Compared with silage straw after 30 days of fermentation, the nutritional quality and fermentation quality of straw were significantly improved after 60 days of fermentation. Lactobacillus plantarum, cellulase and xylanase could improve the silage performance of broom sorghum straw by improving the microbial community structure in straw, and the effect of cellulase was the best. When cellulase was used in straw at the standard of 20 U/g FM, the content of water-soluble carbohydrates could be significantly increased to 31.35 g/kg FM, and the concentration of lactic acid was also significantly increased to 23.79 g/kg FM. Therefore, in actual production, it is recommended to use cellulase at a dose of 20 U/g FM in broom sorghum silage and open the bag after 60 days of silage fermentation. The results of this study provided a scientific basis for the efficient utilization of broom sorghum straw as feed.

Simulating column splice fracture and post‐fracture response for seismic assessment of steel moment frames

AbstractMitigating fracture in welded column splices is an important challenge for the safety of existing steel moment‐resisting frames. While models to predict splice fracture have recently been developed, suitable approaches are not available to simulate the response of frames after splice fracture. Motivated by this, a two‐dimensional displacement‐based fiber element construct, termed the Splice Fracture Element (SFE), is presented. The SFE includes numerous features: (1) representation of the loss of strength in any fiber at a critical stress determined from fracture mechanics, (2) the ability to simulate the loss of shear strength of the cross‐section when the entire section is severed – a phenomenon not readily simulated in conventional fiber elements, and (3) the ability to track the kinematics of the severed parts of the column to represent transfer of compressive stresses on contact. This formulation is implemented into an open‐source software (OpenSees) and applied to conduct Nonlinear Response History Analysis (NLRHA) of two demonstration problems, including a 1‐story frame and a 20‐story frame. Benchmark simulations that do not simulate splice fracture or represent it without the loss of shear strength are also conducted. The results indicate that the SFE element can successfully simulate the key phenomena associated with splice fracture and post‐fracture response.

Current status of technological advancement of ultrasound processing in the food industry and its SWOT analysis.

The use of conventional food processing techniques has almost vanished due to increase in demand with respect to time, thus opening new avenues for emerging technologies. Ultrasound (US) is a rapid, multifaceted, promising, and noninvasive green technology. It has attracted the attention of both industrial experts and scientists for its probable use in food processing and preservation. Using US, fully reproducible food processes can be accomplished in seconds or minutes with increased reliability, minimal processing cost, streamlined manipulation, elevated clarity to the end product, and expending only a fragment of the time and energy commonly required by conventional processes.This review emphasizes on the applications of ultrasound in different food sectors along with its certain limitations. Several operations such as microbial inactivation, enzyme inactivation, extraction, emulsification and fractionation in dairy industries, thermo-sonication in fruit juices have been discussed in detail. The US extracted dietary fiber consisted of increased amount of dietary fiber and trace elements in comparison to alkaline method. US initiate rapid creaming of milk fat, decreasing flavor loss and energy requirements thus enhancing the quality of end product. SWOT analysis has been carried out to pinpoint the strengths, weaknesses, opportunities and threats of sonication in various food industries.

Behavior of CFRP confined rectangular high-strength concrete-filled steel tubular columns under eccentric compression

This paper presents an experimental study on the eccentric compression behavior of rectangular high-strength concrete-filled steel tubular columns confined with carbon fiber reinforced polymer (CFRP- CFST). Seventeen specimens were tested under eccentric compression, examining key parameters involving eccentricity, number of transverse CFRP layers, slenderness ratio, corner radius, CFRP partial wrapping scheme, and CFRP orientation. The effects of these parameters on failure mode, load-displacement relationship, strain development, and ultimate mechanical properties were analyzed and discussed. The ultimate bearing capacity (Nu) of CFRP-CFST columns improved with an increase in transverse CFRP layers, corner radius, and CFRP wrapping proportion, while it decreased with increasing eccentricity and slenderness ratio. Partial wrapping schemes reduced the effectiveness of CFRP confinement, with the outward local buckling of the steel tube primarily occurring in areas without CFRP confinement. Longitudinal CFRP provided less improvement to Nu compared to transverse CFRP under small eccentricity conditions. A theoretical model based on the fiber element method was developed to predict the ultimate bearing capacity and implemented through a custom program to facilitate calculations. The model was validated using a test database comprising results from this study and previous research. Additionally, axial force-bending moment (N-M) interaction curves were rapidly generated, providing a theoretical basis for the design and practical application of CFRP-CFST columns in practical engineering.

Connections between precast hollow concrete columns and foundations using UHPC and rebar lap splices

Hollow concrete columns (HCC) have been widely used in accelerated bridge construction worldwide. The column-foundation connections are vital in such precast systems to ensure seismic resilience. In this paper, a novel HCC-foundation connection using UHPC and rebar lap splices was proposed, which could facilitate the construction process. Cyclic tests were carried out on four specimens to examine their seismic performance. Test results showed that the proposed connections exhibited satisfying capacities, ductility, and energy dissipation comparable to monolithic connections under lateral cyclic loads. The use of a precast UHPC shell did not deteriorate the performance of the connection with no interface separation observed. The decrease in joint height would, however, bring about anchor rebar slippage and reduce energy dissipation. A validated fiber element model of the specimens was established for efficient seismic modeling of precast systems with the proposed connection in actual projects. Force transfer mechanisms and design methods for the connections were further deduced. The proposed connection has been verified to be comparable to cast-in-place connections and is thus suitable for use in precast column-foundation connections. Several design recommendations were derived for engineering reference.

Experimental study on concrete-filled L-shaped steel tubular columns and beam-columns

Concrete-filled L-shaped steel tube (CFLST) is an efficient structural form for corner columns in high-rise buildings, which avoids column protrusion. This paper presents an experimental and theoretical study on the structural behavior of CFLST columns and beam-columns. A total of nine full-scale specimens (i.e., three stub columns, two slender columns, and four slender beam-columns) was tested under compressive loads and the specimen ends were free to rotate about a geometric axis. Plastic local buckling was observed for the stub columns and the confinement effect was not obvious. Flexural buckling occurred for the slender columns and beam-columns. With the increase in the applied load, the neutral axis shifted to the compressive side of the beam-column. Performance of current design codes, which apply for rectangular CFSTs, on predicting the ultimate capacities of CFLSTs was assessed. The prediction for section capacity was conservative and it was likely caused by the reduction in the design strength of concrete. The buckling curve in design codes for rectangular CFSTs was applicable for CFLST columns whereas the interaction relationship specified in design codes underestimates the ultimate capacities of CFLST beam-columns. Based on fiber element analysis, out-of-plane bending moment was found in the tested CFLST slender members and the values were quantified. A new interaction relationship was proposed for CFLST beam-columns, which exhibited good agreement with experimental and numerical results. Finally, design methods were recommended for CFLST columns and beam-columns.

Flexural mechanical properties of H-shaped steel-bamboo scrimber composite beams

To improve the torsional buckling resistance and enhance the load-bearing capacity and ductility of H-shaped steel beams with carbon reduction materials, the concept of combining H-shaped steel with bamboo scrimber has been proposed, in which the bamboo scrimber, an eco-friendly, lightweight, and high-strength material, promises significant structural benefits. Five full-scale specimens were designed and tested, including one H-shaped steel, two bamboo scrimber beams, and two composite beams. Additionally, further simulation tests were conducted using the verified finite element model (FEM). The experimental results revealed a remarkable increase in the ultimate bearing capacity of the composite beams by 96.5 % compared to bamboo scrimber-only beams and 72.7 % compared to steel-only beams. Meanwhile, distinct from the brittle fracture characteristics of the bamboo scrimber beams, which include instantaneous crack propagation and interlaminar cracking, the composite beams exhibited localized vertical cracks within the beam's tensile zone, effectively avoiding the torsional buckling issue of the H-shaped steel beam. The results further demonstrated that increasing the cross-sectional size of the composite beams can significantly enhance their flexural stiffness (up to 669 %), and reduce the deflection at the ultimate flexural moment. When the area of the bamboo scrimber in the cross-section was reduced with an unchanged steel profile, the initial stiffness dropped to 79 % without incurring any structural instability. Furthermore, by integrating the experimental and simulation results, a fiber element model for this composite beam structure is proposed to predict the maximum flexural moment value in the ultimate state. A corresponding calculation program was developed, and it is found that the calculated predicted ultimate flexural moment values exhibited negligible deviation from both experimental and FEM results, with AV of 1.0001, AAE of 2.21 %, and COV of 3.28 %.

Experimental and numerical study on seismic behavior of shear wall with cast‐in situ concrete infilled walls

AbstractThe shear wall system with cast‐in situ concrete infilled walls has been widely used in high‐rise buildings due to its significant advantages in construction. In this paper, quasi‐static tests were conducted on the shear walls with and without cast‐in situ concrete infilled walls to analyze their failure modes, load‐bearing capacity, stiffness, energy dissipation capacity, and ductility. A simplified model of the shear wall with cast‐in situ concrete infilled walls was proposed based on the fiber element model in OpenSees. The test results showed that the shear wall specimens with cast‐in situ concrete infilled walls exhibited full‐section compression or tension failure, and the cast‐in situ concrete infilled walls did not show obvious damage. Compared with the shear wall without infilled walls, the overall stiffness, load bearing capacity, and energy dissipation capacity of the shear wall specimens with cast‐in situ concrete infilled walls improved, indicating better seismic performance than those without infilled walls. Comparison between the hysteresis and skeleton curves derived from the tests and those simulated by the proposed simplified model revealed errors within 15% for stiffness, yield bearing capacity, and ultimate bearing capacity for shear walls with cast‐in situ concrete infill walls, affirming the effectiveness and accuracy of the model.

Numerical Relaxation Analysis of Carbon Fiber Reinforced Polymers

AbstractCarbon fiber reinforced polymers are widely used to manufacture aerospace deployable structures. These structures are folded in launch configuration and then deployed in space for operational activities. Since the stowage of deployable structures in folded configuration occurs for long time, the understanding of the viscoelastic properties of the material is essential to predict the structural behavior during both the deployment phase and the operational life. In this work, numerical relaxation analysis is performed on the representative volume element (RVE) of a carbon fiber reinforced polymer using a homogenization approach at the microscale. This aims to predict the effects of matrix viscoelasticity on the structural performance of a deployable structure.

Earthquake Performance Analysis of a Masonry School Building's Retrofitted State by the Equivalent Frame Method

Nonlinear analyses of masonry structures are frequently used in both engineering practice and academic studies. Due to the dominant nonlinear behaviour of masonry structures, complex and extensive finite element models are required to obtain accurate analysis results. While masonry walls are usually modelled using fine-meshed shells or solid elements in such structures, high computing power in modelling, analyzing, and post-processing results is necessary for the analyses of large structures. In recent years, the equivalent frame method, as a solution to this problem has been developed and presented in the literature. In this study, the equivalent frame method is used in a masonry structure modelling, and the axial force-bending relationship is represented by force-based fiber elements. The multi-linear load-deformation relationship reflects the shear behaviour of the walls. Within the scope of the study, an existing masonry school building is modelled using the equivalent frame elements with OpenSees software. Seismic performance analyses are done considering the existing and retrofitted states of the structure, and the results are discussed in a comparative manner.

Discrete Element Method Simulation of Particulate Material Fracture Behavior on a Stretchable Single Filter Fiber with Additional Gas Flow

This study presents a comprehensive discrete element method (DEM) simulation approach for the stretching of a filter fiber with a separated polydisperse particle structure on top. For a realistic interaction between the fiber surface and the particles, the original surface of the polymer fiber was projected onto the surface of the fiber cylinder using surface imaging technologies (atomic force microscopy (AFM) and white-light interferometry). In addition, the adhesive forces between particle–fiber and particle–particle contacts were calibrated in the DEM domain using values from self-conducted AFM measurements. Fiber stretching was implemented by the linear motion of small periodic fiber elements. Discretization problems were resolved through studying the stretching of a fiber segment at the size of 8 mm. A critical fiber element length was discovered to be ≈100 μm for minimizing discretization dependencies during the cracking of the particle structure. The number and density of particle–particle contacts within the particle loading on the fiber were obtained at two different elongation rates. Effects such as densification of the particulate structure and increased detachment due to additional air flow were demonstrated.

Slenderness effects on concrete-filled square steel tube columns strengthened with CFRP grid-reinforced ECC matrix

This study presents an experimental investigation aim at evaluating the slenderness effects on concrete-filled square steel tube columns strengthened with a carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite matrix. Thirteen columns were subjected to axial compression, with the studied parameters including the length-to-width (L/B) ratio, CFRP grid layer number, concrete strength grade, and width-to-thickness ratio of the steel tube. Test results revealed that slender columns experienced an increase in load-bearing capacity ranging from 27.1 % to 32.4 % after strengthening, while the ductility enhancement reached a peak of 52.0 %. A column with an L/B ratio of 5.87 exhibited slight bending deformation in a localized region upon failed, with CFRP grid ruptured at the corner. While columns with L/B ratios of 7.83 and 9.78 failed due to the loss of stability, displaying overall bending deformation. The increase in L/B ratio accelerated the loss of stability, resulting in a decrease in the ultimate load. As the L/B ratio increased from 2.97 to 5.93, 7.91 and 9.89, the ultimate loads of the strengthened columns decreased by 7.4 %, 9.2 %, and 15.4 %, respectively. A load-bearing capacity calculation model of slender strengthened columns was developed using the fiber element method. Through numerical analysis, a stability coefficient was introduced, and a simplified calculation formula was proposed to predict the stability bearing capacity.

Tensile Forces Behavior on Longitudinal Reinforcement and CFRP Strips on Circular Hollow Reinforced Concrete Columns

Abstract Currently, there is not much research on strengthening structural elements with hollows. This manuscript presents the test results from twelve circular reinforced concrete column specimens strengthened with CFRP strips. This study focuses on the strain behavior of longitudinal reinforcement and CFRP strips due to high shear force intensity. Hollows in the cross-section are used to see the effect of voids on the column strain distribution. Nine specimens have a hollow cross-section with hollow diameters of 1.5", 2.5", and 3.5" for each of the three specimens. Meanwhile, the other three specimens have a solid crosssection. All specimens do not use stirrups to determine the contribution of concrete and CFRP strips to resist shear. Strain gauges are placed in certain positions to read the strain on the longitudinal reinforcement and CFRP strips. The test results are in the form of tensile forces and are then analyzed to obtain the movement pattern of tensile forces in the longitudinal reinforcement and CFRP strips. Numerical analysis using a fiber element model is used to obtain the strain in each reinforcement layer. The numerical analysis results were then compared with the test results and showed close results. Then, an equation for calculating the tensile force in CFRP strips is proposed. The proposed equation approximates the test results with an accuracy level of 90%.

Exploring seismic resilience in frame structures through advanced numerical modeling and dynamic nonlinear analysis of recycled aggregate concrete

This study developed an advanced three-dimensional spatial model to examine the behavior of Recycled Aggregate Concrete (RAC) frame structures using sophisticated nonlinear beam-column fiber elements. It thoroughly investigates the dynamic properties such as natural frequency, vibration modes, and stiffness of RAC structures and conducts a detailed nonlinear dynamic analysis focusing on acceleration, displacement, drift, and hysteresis curves. The seismic resilience of RAC structures, especially inter-story drift under various seismic intensities, was evaluated and compared with Natural Aggregate Concrete (NAC) structures by adjusting the concrete material model parameters in the finite element framework. The accuracy of the numerical model was validated against shaking table tests, showing that RAC and NAC structures comply with structural damage criteria across seismic phases from 0.066 g to 1.170 g. The findings suggest RAC structures are as seismically resilient as NAC ones, making them suitable for earthquake-prone areas.

Prediction of the performance of reinforced concrete elements under monotonic and cyclic lateral loading

Introduction: The nonlinear behavior of reinforced concrete elements under monotonic and cyclic loading is one of the most important research topics in seismic regions. Over the past 30 years, several experimental investigations have been conducted with the aim of better understanding the behavior of reinforced concrete elements and determining the various parameters influencing this behavior. Purpose of the study: The present research investigates this behavior and aims to develop an interactive computer program designed for use within the Windows environment. Methods: Several material models (confined/unconfined concrete and reinforcing steel), as well as hysteresis laws, are employed in an analytical approach using the fiber element. For each specimen, geometric characteristics, material models, plastic hinge locations, axial loads, and the history of corresponding horizontal displacements were input into the program. Numerical predictions are validated against experimental results from diverse studies. Results: Convergence analysis using experimental data demonstrated good agreement between numerical and experimental results, particularly in hysteresis behavior, force-displacement envelope curves, maximum strength, initial stiffness, stiffness degradation, and cumulative energy dissipation. The findings underscore the efficacy of the developed program in accurately predicting the nonlinear behavior of reinforced concrete elements. The developed program provides a reliable tool for predicting the nonlinear behavior of reinforced concrete elements under cyclic loading, validated through convergence analysis with experimental data.

High Performance Proprioceptive Fiber Actuators Based on Ag Nanoparticles-Incorporated Hybrid Twisted and Coiled System.

Thermally driven fiber actuators are emerging as promising tools for a range of robotic applications, encompassing soft and wearable robots, muscle function restoration, assistive systems, and physical augmentation. Yet, to realize their full potential in practical applications, several challenges, such as a high operational temperature, incorporation of intrinsic self-sensing capabilities for closed-loop feedback control, and reliance on bulky, intricate actuation systems, must be addressed. Here, an Ag nanoparticles-based twisted and coiled fiber actuator that achieves a high contractile actuation of ≈36% is reported at a considerably low operational temperature of ≈83°C based on a synergistic effect of constituent fiber elements with low glass transition temperatures. The fiber actuator can monitor its contractile actuation in real-time based on the piezoresistive properties inherent to its Ag-based conductive region, demonstrating its proprioceptive sensing capability. By exploiting this capability, the proprioceptive fiber actuator adeptly maintains its intended contractile behavior, even when faced with unplanned external disturbances. To demonstrate the capabilities of the fiber actuator, this study integrates it into a closed-loop feedback-controlled bionic arm as an artificial muscle, offering fresh perspectives on the future development of intelligent wearable devices and soft robotic systems.

Effect of Fiber Orientation and Volume Fraction on Young's Modulus for Unidirectional Carbon Fiber Reinforced Composites: A Numerical Investigation

The modulus of elasticity of unidirectional fiber-reinforced composites greatly depends on the fiber orientation and the fiber volume fraction. This paper investigates the effects of fiber orientation and fiber volume fraction using the commercially available Finite Element Analysis (FEA) software Abaqus. Carbon fiber is the reinforcing material, while epoxy is used as the matrix. Representative Volume Element (RVE) of the unidirectional carbon fiber reinforced composites are modeled in Abaqus, and the unidirectional tensile test is simulated to determine the modulus of elasticity for different fiber orientations and fiber volume fractions. The numerical results are verified by previously published results and by experimental results. It is found that the modulus of elasticity of the composite is maximum when the fiber inclination angle is 0°, i.e., the fibers are placed along the loading direction. As the fiber orientation angle increases, the modulus of elasticity also decreases and is almost constant after 45°. A linear increase in modulus of elasticity is observed for an increase in fiber volume fraction. This model will help the researcher to select the appropriate fiber orientation and volume fraction for a specific application.

Simulation of the Childbirth Process in LS-DYNA.

Childbirth or labor, as the final phase of a pregnancy, is a biomechanical process that delivers the fetus from the uterus. It mainly involves two important biological structures in the mother, the uterus-generating the pushing force on the fetus-and the pelvis (bony pelvis and pelvic floor muscles)-resisting the movement of the fetus. The existing computational models developed in this field that simulate the childbirth process have focused on either the uterine expulsion force or the resistive structures of the pelvis, not both. An FEM model including both structures as a system was developed in this paper to simulate the fetus delivery process in LS-DYNA. Uterine active contraction was driven by contractile fiber elements using the Hill material model. The passive portion of the uterus and pelvic floor muscles were modeled with Neo Hookean and Mooney-Rivlin materials, respectively. The bony pelvis was modeled as a rigid body. The fetus was divided into three components: the head, neck, and body. Three uterine active contraction cycles were modeled. The model system was validated based on multiple outputs from the model, including the stress distribution within the uterus, the maximum Von Mises and principal stress on the pelvic floor muscles, the duration of the second stage of the labor, and the movement of the fetus. The developed model system can be applied to investigate the effects of pathomechanics related to labor, such as pelvic floor disorders and brachial plexus injury.

Thermoplastic composite injection-overmoulding with indirectly-loaded reinforcement: Design for manufacture

Thermoplastic Overmoulding is an emerging manufacturing method combining low-cost, high-rate injection moulding with continuous fibre composite elements. The combination of materials with dissimilar stiffnesses can create stress concentrations and warpage, with further complications caused by high injection pressures distorting the continuous fibre elements (wash). This study uses a numerical model to consider a particular overmoulding approach that utilises a strategically positioned local reinforcing element (an insert) that is loaded indirectly via stresses transferred from the surrounding overmoulding material. This offers a low-cost solution by minimising use of continuous fibre material, but has a higher likelihood of the aforementioned problems. A geometrical solution (a waffle-type structure) is used to address these manufacturing challenges without compromising the primary stiffening role of the continuous fibre element. An insert efficiency factor is proposed to describe the tensile behaviour and the diminishing returns on peak load in the insert when embedding increasingly higher stiffness inserts into moderate stiffness overmoulding materials containing short fibres. According to the simulation results, the proposed Waffle structure should provide stiffness commensurate with the conventional configuration; however, the experimental coupons highlight the complexities of injection moulding short fibres and indicate the detrimental effect of anisotropic fibre distributions within the overmoulded sections.

Araucaria angustifolia seed coat waste reduction through its utilization in substrate diversification for Pleurotus djamor production

Mushrooms of the genus Pleurotus are the second most cultivated and consumed variety worldwide due to their nutritional profile and the efficient use of agricultural and forestry residues as substrates. In order to explore the efficiency of seed coat lignocellulose from Araucaria angustifolia (pine nut) seeds (PSC) as a substitute substrate (20 %, 40 %, 60 % or 80 %) of Eucalyptus sawdust for the production of Pleurotus djamor (PD) was estimated the number of fruiting bodies (NFB), biological yield (BY), biological efficiency (BE), and nutritional and mineral composition. The PSC was separated from the almond seed, dried, ground and used as an alternative substrate (0–80 %) to Eucalyptus sawdust (400 g), which was mixed with wheat bran (97 g) and CaCO3 (3 g). Due to a higher Carbon/Nitrogen ratio of a PSC substrate, it was better compatibility for a fungal enzymology of PD mushroom than E. urograndis sawdust substrate. The substrate enriched with 40 % PSC exhibited elevated ash content (minerals) and reduced moisture levels, higher carbon/nitrogen ratio, optimal conditions for NFB, and increased BY and BE. PD showed significant levels of dietary fiber and essential elements, including Cu, Fe, P, Mn, Mg, and Zn, with minimal fat content. Araucaria angustifolia waste reduction through its utilization in substrate diversification for PD production brings about favorable environmental and societal outcomes, improving both the mushroom yield and their nutritional content. This approach serves as an environmentally sustainable solution for pinhão seed coat waste and should be encouraged and extended for broader use.