Shear Tests Research Articles

Characterization of Amnion-Derived Membrane for Clinical Wound Applications.

Human amniotic membrane (hAM), the innermost placental layer, has unique properties that allow for a multitude of clinical applications. It is a common misconception that birth-derived tissue products, such as dual-layered dehydrated amnion-amnion graft (dHAAM), are similar regardless of the manufacturing steps. A commercial dHAAM product, Axolotl Biologix DualGraft™, was assessed for biological and mechanical characteristics. Testing of dHAAM included antimicrobial, cellular biocompatibility, proteomics analysis, suture strength, and tensile, shear, and compressive modulus testing. Results demonstrated that the membrane can be a scaffold for fibroblast growth (cellular biocompatibility), containing an average total of 7678 unique proteins, 82,296 peptides, and 96,808 peptide ion variants that may be antimicrobial. Suture strength results showed an average pull force of 0.2 N per dHAAM sample (equating to a pull strength of 8.5 MPa). Tensile modulus data revealed variation, with wet samples showing 5× lower stiffness than dry samples. The compressive modulus and shear modulus displayed differences between donors (lots). This study emphasizes the need for standardized processing protocols to ensure consistency across dHAAM products and future research to explore comparative analysis with other amniotic membrane products. These findings provide baseline data supporting the potential of amniotic membranes in clinical applications.

A hyperelastic model considering the coupling of shear-compression for the forming simulation of 3D orthogonal composite preforms

The shear-compression coupling phenomenon is vital in the forming process of complex 3D woven composite components, but has not been effectively considered in existing macroscopic material models. A hyperelastic material model considering shear-compression coupling is developed here. Firstly, in-plane shear tests on pre-compressed specimens and compression tests on pre-sheared specimens were carried out, respectively. The results show that pre-compression can hinder and promote the in-plane shear deformation before and after shear locking occurs in the fabric, respectively. In-plane shear can contribute to compression. Then, a nonlinear hyperelastic constitutive model is presented and implemented in an Abaqus/Explicit user subroutine. Finally, a simulation study of the hemispherical forming of 3D orthogonal woven fabric was conducted using this model. The simulation results considering shear-compression coupling show more accurate in-plane shear angles and edge shapes compared to those without considering coupling. Moreover, since the shear-compression coupling is considered, the friction between the fabric and the tool needs to be reasonably discussed in the moulding simulation.

Fracture mechanisms of Al-steel resistance spot welds: The role of intermetallic compound phases

This study explores the mechanical and metallographic characteristics of Al-Steel dissimilar resistance spot welds (RSW), with a particular focus on the intermetallic compound (IMC) phases and their impact on fracture mechanisms. Detailed metallographic analyses and novel miniature lap shear tests with in-situ Digital Image Correlation techniques were conducted to observe the crack propagation behavior. The findings revealed that the IMC phases significantly influence the crack path and fracture mechanisms, leading to variations in fracture energy. Specifically, three distinct IMC phases were identified at the weld interface, each exhibiting unique structural and mechanical properties, with corresponding fracture energies of approximately 0.03 kJ/m2, 1.1 kJ/m2, and 7.5 kJ/m2. These variations highlight the critical role of the IMC phase in determining the fracture behavior of the weld. The study further supported the development and validation of a finite element (FE) model, incorporating a Cohesive Zone Model to simulate debonding behavior and the Hosford-Mean fracture criterion to predict ductile fracture in the Al fusion zone, thereby successfully linking local material characteristics to mechanical properties.

Experimental investigations of the shear strength and deformation behavior of a frozen unsaturated silt

There are limited studies in literature with respect to the deformation and shear strength behavior of frozen unsaturated soils that consider sensitive changes in temperatures below 0 °C. For this reason, the focus of the present study is directed towards investigating the shear strength and deformation behavior of a frozen unsaturated silt. As a part of the study, one-dimensional freezing tests were performed on compacted silt samples with various initial water contents and dry densities. The pulsed nuclear magnetic resonance (P-NMR) method was used to obtain distribution of unfrozen water content of silt samples; this information was used to explain the deformation behavior during freezing. The volume change behavior in unsaturated soils due to freezing can be associated to three primary factors: expansion caused by the ice-water phase transition and shrinkage induced by ice-cementation and dehydration. A critical water saturation was also observed at which the frost heave is minimum, or no volume change occurs. In addition, conventional direct shear tests were performed on compacted unsaturated silt samples both in frozen and unfrozen conditions to determine and quantify the shear strength contribution arising from the different cohesion components. The investigations in this study provide valuable information that can be used in rational explanation of the strength and deformation behavior of unsaturated frozen soils.

Expanding Lightweight Design Potential by Hybrid Joining of Aluminum Sheets with Aluminum Casting Through Compound Sand Casting and Induction Heating

Combining light metals like aluminum to produce lightweight structures offers a high weight‐saving and contributes to a circular economy in automotive car body construction. Compound casting is a promising process for producing car body parts. Difficulties arise in creating metallic continuity between insert and casting. Insert coatings are used to remove the oxide layer and thereby improve the wettability of the melt. This study uses a hybrid joining method to improve the metallic bond between insert and casting. Induction heating differently influences the strength properties of age‐ and nonage‐hardenable inserts. Compression shear tests characterize the metallic bond strength. Microscopic images show the influence of the process variables on the compound quality. Reproducible sound metallic bonding with low scattering is achieved by enhancing the compound casting process through induction and no insert coating. Cast wall thicknesses down to 4 mm contribute to further lightweight potential as they have the same strength level as the reference sample. A decisive factor is the insert temperature in the compound zone. Thereby, insert preheating conditions play a crucial role. Additional heat treatment of hardenable compounds leads to a further increase in metallic bond strength.

Study on shear performance of BMSCC prefabricated shell and square steel tube composite permanent formwork beam

A novel type of permanent formwork (PF) concrete beam has been proposed with the aim of reducing carbon footprint, conserving energy, and enhancing construction efficiency. Specifically, the U-shaped PF is constructed using basic magnesium sulfate cement mortar, and square steel pipes with holes are utilized in place of traditional vertical and horizontal reinforcements. During on-site construction, the composite beam can be easily completed by pouring ordinary concrete into the PF. Shear failure tests were conducted on two PF beams and a reinforced concrete (RC) contrast beam with varying strip spacing. It was observed that the remaining rectangular steel strips, resulting from opening holes on both sides of the square steel pipe, acted as shear stirrups. The results indicate that the PF beam demonstrates typical shear and compression failure, and the precast shell is securely bonded to the core concrete without any peeling phenomenon. When comparing to an equivalent RC beam with the same transverse steel yield strength and dosage, the cracking load of the inclined section is increased by 28.3 % and the ultimate load is increased by 21.4 %. Compared to RC beams, PF beams exhibit an increased number of cracks but reduced width. And The ductility of PF beams were improved. Decreasing the distance between steel strips on both sides of the PF beam results in an 10.3 % increase in cracking load and a 9.4 % increase in ultimate load. By introducing the concrete constraint coefficient and the steel tube web resistance coefficient, the formula for calculating the shear capacity of the PF beam was established.

Influence of Dentin Sealing Technique on the Shear Bond Strength between Lithium Disilicate Ceramics and Try-In-Paste-Contaminated Dentin

This study aimed to evaluate the effect of try-in paste contamination on the bond strength of lithium disilicate glass–ceramic to dentin treated with immediate (IDS) or delayed (DDS) dentin sealing techniques. Occlusal halves of 33 molars were decapitated and divided into three groups (n = 10). Lithium disilicate discs (3 × 5 mm) were prepared. For Group A, the provisional crown was applied over dentin and was soaked in distilled water. Lithium disilicate discs were cemented following dentin conditioning with a three-step etch and rinse adhesive. In Group B (IDS), the three-step adhesive was applied to dentin. The dentin surfaces were conditioned only in the final cementation for Group C (DDS). The intaglio surfaces of test groups were contaminated with try-in paste. All specimens were thermally cycled 3000 times at 5–55 °C and were subjected to shear tests. An additional three specimens for each group were contaminated with try-in paste and subjected to the same surface cleaning as the test specimens were examined with SEM/EDS. The adhesive surfaces were also examined with SEM/EDS for try-in paste remnants. Group C showed a significant decrease in bond strength values compared to Group B and Group A (5.84 ±1.4 MPa, 11.45 ±2.4 MPa, and 10.29 ±2.5 MPa, respectively). No statistically significant difference was detected between Group B and Group A (p ≥ 0.05). The SEM-EDS analyses revealed obstructions of the dentinal tubules in the try-in-paste-contaminated specimens. Immediate dentin sealing application enhanced the bonding strength of lithium disilicate to the try-in-paste-contaminated dentin. Try-in paste contamination over dentin negatively influenced the bonding process.

Effect of surface treatment on interface properties of carbon fiber reinforced PA6 composites during overmolding

AbstractCarbon fiber‐reinforced thermoplastic composites have the advantages of lightweight and high strength and have broad application prospects in automotive lightweighting. This study uses the Overmolding process to mold carbon fiber‐reinforced nylon 6 composite materials. By using laser surface treatment and preheating technology, the interfacial bonding performance of the composite material is emphasized. By optimizing the embedding temperature, it was observed that the in‐plane shear strength increased by 13 times to 70 MPa, and the tensile strength increased by 10 times to 44 MPa. Similarly, by adjusting the melting temperature, the in‐plane shear strength was significantly improved, and the mechanical interlock and interfacial bonding were effectively enhanced by laser surface treatment, achieving the same effect as embedding preheating. By establishing a finite element model, the in‐plane tensile and in‐plane shear at the interface were accurately simulated, and the progressive failure process of the interface layer was successfully predicted.Highlights Laser energy density strengthens the overmolding interface. Optimizing insert, mold, and melt temperatures enhances interface bonding. Shear and tensile tests reveal differences in interface failure behavior. Finite element model accurately simulates overmolding interface failure. Laser treatment and temperature control are key to stronger interfaces.

Advanced modeling of higher-order kinematic hardening in strain gradient crystal plasticity based on discrete dislocation dynamics

An extensive study of size effects on the small-scale behavior of crystalline materials is carried out through discrete dislocation dynamics (DDD) simulations, intended to enrich strain gradient crystal plasticity (SGCP) theories. These simulations include cyclic shearing and tension-compression tests on two-dimensional (2D) constrained crystalline plates, with single- and double-slip systems. The results show significant material strengthening and pronounced kinematic hardening effects. DDD modeling allows for a detailed examination of the physical origin of the strengthening. The stress–strain responses show a two-stage behavior, starting with a micro-plasticity regime with a steep hardening slope leading to strengthening, and followed by a well-established hardening stage. The scaling exponent between the apparent (higher-order) yield stress and the geometrical size h varies depending on the test type. Scaling relationships of h−0.2 and h−0.3 are obtained for respectively constrained shearing and constrained tension-compression, aligning with some experimental observations. Notably, the DDD simulations reveal the occurrence of the uncommon type III (KIII) kinematic hardening of Asaro in both single- and double-slip cases, emphasizing the relevance of this hardening type in the realm of small-scale plasticity. Inspired by insights from DDD, two advanced SGCP models incorporating alternative descriptions of higher-order kinematic hardening mechanisms are proposed. The first model uses a Prager-type higher-order kinematic hardening formulation, and the second employs a Chaboche-type (multi-kinematic) formulation. Comparison of these models with DDD simulation results underscores their ability to effectively capture the observed strengthening and hardening effects. The multi-kinematic model, through the use of quadratic and non-quadratic higher-order potentials, shows a notably better qualitative congruence with DDD findings. This represents a significant step towards accurate modeling of small-scale material behaviors. However, it is noted that the proposed models still have limitations, especially in matching the DDD scaling exponents, with both models producing h−1 scaling relationships (i.e., Orowan relationship for precipitate size effects). This indicates the need for further improvements in gradient-enhanced theories in order to guarantee their suitability for practical engineering applications.

Critical state uniqueness of dense granular materials using discrete element method in conjunction with flexible membrane boundary

An explanation of the meso-mechanism of sand granular materials for the uniqueness of critical state is presented by means of the discrete element method (DEM) under flexible boundary loading conditions. A series triaxial drainage shear test (DEM simulations), in conjunction with the flexible boundary technique, of were performed for sand samples subjected to various physical states and with different particle size distributions. After carefully investigating the critical status of the results of the numerical calculation, the macroscopic failure modes and shear band evolution of sand, as well as the velocity vector field due to different initial states, were explored and classified. Furthermore, the evaluation rules and discrepancies between overall void ratios of the specimen and local void ratios within the shear band under the critical state were recorded and analyzed. The results proved that a sample with a small void tends to form a shear band, and the rotation of the particles in the non-shear zone is negligible. Conversely, sandy soil with large initial void ratios exhibited limited development of significant shear bands, and the change in void ratios within the shear region and the non-shear area are not significant. Interestingly, the particle-size distribution exerts minimal influence on the evolution rule which the void ratio converges within the shear band and diverges outside the shear region for both multi-stage and single-stage specimens. The void ratio within the shear band and deviator stress ratio tend to exhibit consistently for the same specimen with different initial physical states, thereby distinguishing the critical state. There is a significantly higher change in void ratio within the shear band compared to outside of it, yet it remains stable within a relatively similar range. Additionally, the invariant of the fabric tensor used to describe the critical state characteristics also demonstrates a high degree of consistency within the shear band. These findings strongly indicate that the critical state exists within the shear failure surface and is highly likely to be unique.

Experimental study on shear transfer across interfaces with post-installed shear reinforcement

To address the fit-up issues arising from reinforcement congestion and limited seating area over precast beams, an improved joint detail characterized by post-installed interface shear reinforcement has been developed. The incorporation of post-installed narrower looped bars as an alternative to conventional protruding stirrups significantly expedites the erection of precast flooring systems. Moreover, direct shear tests are performed on 30 Z-shaped specimens to investigate the influence of joint details, surface roughness, looped bar ratio, and embedment length of post-installed bars on the interface shear behavior. Experimental results indicate that employing post-installed narrower looped bars not only ensures adequate seating length for precast flooring systems, but also prevents the splitting failure of concrete cover which can induce the degradation of dowel action. Sufficient anchorage is the prerequisite for post-installed looped bars to impose clamping stress on concrete interface, and a shallow embedment length may trigger the occurrence of pull-out failure. Surface roughness is another factor determining the interface shear resistance and stiffness. Untreated surfaces, in contrast to intentionally roughened surfaces, are susceptible to the cohesion fracture and may hinder the development of shear-friction action. Furthermore, a linear correlation exists between looped bar ratio and the shear resistance of concrete interface. Based on the experimental results, design recommendations, including the minimum required anchorage length for post-installed looped bars, are proposed for the novel joint detail.

Influences of the normal loading condition and surface texture on interface shear behavior between sand and suction caisson wall

The mechanical behavior of the interface between soil and the suction caisson wall determines the installation behavior and bearing capacity. A series of interfacial shear tests are conducted to study the effects of the normal loading condition and the interface texture on the sand-suction caisson interface shear characteristics. The relative density of the sand used in the test is 0.9. It is found that with the increase of shear displacement, the shear stress-displacement curve under a constant normal load condition (CNL) has an obvious strain-softening trend. On the contrary, the shear stress increases linearly with increasing the shear displacement under a variable normal load condition (VNL). The stress ratio between shear and normal stress, the broken zone thickness, and the shear deformation zone thickness for a convex suction caisson wall-sand interface are significantly larger than those of the grooved interface. However, when the roughness increases to a certain value, the stress ratio between shear and normal stress would decrease. Under large displacement shearing, the degree of sand particle breakage becomes significantly higher than that under small displacement shearing. These results help understand the shear characteristics of the sand-suction caisson wall and invent the new type of the suction caisson.

INNOVATIVE EXPERIMENTAL TESTING PROGRAM OF DIRECT SHEAR TEST IN SOIL MECHANICS

The research work aims at analyzing for the first time the data set obtained on cohesive soil samples following the publication of the Romanian Invention Patent RO 134239. The standard test method for the direct shear test provides the shear strength parameter – internal friction angle in consolidated drained condition - of either undisturbed or remolded soil samples forcing the shear plane at the midsection of the sample in the horizontal direction. The samples are provided in parallelepipedal shape (6 cm x 6 cm x 2 cm) and the displacement rate in horizontal direction is 0.1 mm/min. The new equipment patented in Romania changes the direction of shearing, from horizontal to vertical, and the soil samples are of cubic shape (6 cm x 6 cm x 6 cm). The experimental program involves testing both the parallelepipedal and cubic samples using the same motorized mechanism, with simultaneous readings from their respective micro-comparators. The UU test is performed without allowing consolidation and shearing at 1.0 mm/min. For the CD test, samples are consolidated under vertical loads for 24 hours before shearing at 0.1 mm/min. The shear stresses for cubic samples were higher than those for parallelepipedal samples, with residual stresses reflecting this trend. For cubic samples, both the peak and residual shear stresses trend lines indicated higher cohesion (c) and lower internal friction angle (𝜙) for UU tests and CD tests in contrast to parallelepipedal samples in both testing conditions. The innovative testing program allows for variability in shear strength parameters along the soil failure surface in both natural and compacted soil structures. This differentiation divides the soil condition into drained and undrained states at the initiation, emergence points, and the point of maximum depth along the failure surface. This approach is significant for accurately assessing soil shear resistance and potential failure mechanisms. The study's findings suggest a nuanced approach to parameter selection for slope stability analysis, ensuring accurate representation of both cohesion and internal friction in stability models.

Experimental study on shear mechanical properties of concrete joints under different unloading stress paths

In order to study the shear mechanical properties of rock joint under different unloading stress paths, the RDS-200 rock joint shear test system was used to carry out direct shear tests on concrete joint specimens with five different morphologies under the CNL path and different unloading stress paths. The unloading stress paths include unloading normal load and maintaining constant shear load (UNLCSL), unloading normal load and unloading shear load (UNLUSL), unloading normal load and increasing shear load (UNLISL). The results show that the peak shear strength, cohesion, internal friction angle, pre-peak shear stiffness and residual shear strength of concrete joints under CNL path increases with the increasing JRC and normal stress. Under the UNLCSL path, under the same initial shear stress τ1, instability normal stress σi decreases with the increasing JRC, and normal stress unloading amount Δσn increases with the increasing JRC. Under the same JRC, σi increases with the increase of τ1, and Δσn decreases with the increasing τ1. Under the same JRC and σi, τi is significantly smaller under the UNLCSL path than the CNL path. Under the same JRC, the cohesion under the UNLCSL path is less than the CNL path, and the internal friction angle is higher than that the CNL path. Under the same JRC and σi, τi is the largest under the path of CNL and UNLISL, followed by the UNLCSL path, and τi under the UNLUSL path is the smallest. Compared with the CNL path, the variation range of the specimen internal friction angle is within 3% while the average decrease percentage of the specimen cohesion reaches 37.6% under the UNLCSL path, UNLISL, and UNLUSL. Therefore, it can be inferred that the decrease in cohesion caused by normal unloading is the main reason for the decrease in joint instability shear strength. After introducing the correction coefficient k of cohesion to modify the Mohr-Coulomb criterion, the maximum average relative error after correction is only 3.5%, which is significantly improved compared with the maximum average relative error of 56.9% before correction. The research conclusions can provide some reference for the accurate estimation of shear bearing capacity of rock joints under different unloading stress paths, which is of great significance to the stability evaluation and disaster prevention of rock mass engineering.

Preparation and performance characterization of waterborne epoxy resin modified asphalt emulsion for tack coat

In order to eliminate the possible drawbacks of waterborne epoxy resin (WER) generated by the phase inversion method and the chemical modification method, this study prepared WER using a novel method, i.e., epoxy resin was introduced into the molecular structure of aqueous acrylic resin; after the combination of epoxy resin and the aqueous dispersion process, the aqueous epoxy acrylic resin can be prepared. Waterborne epoxy resin modified emulsified asphalt (WEREA) was then prepared for the application of a tack coat material. Fourier Transform Infrared Spectroscopy (FTIR) test was conducted to explore the possible reactions between the compositions. A rheology test, direct tension test, pull-off bonding test, and oblique shear test were also conducted. Results indicated that in the FTIR test, a new peak around 1732 cm−1 was formed due to the reaction between the carboxyl functional group in WER and the amino group in curing agent to form an ester bond. The incorporation of WER led to an elevation in the complex modulus and a simultaneous reduction in the phase angle of WEREA. When the temperature was larger than 60 °C, the phase angle showed a decreased trend, indicating the material became less viscous due to the increased temperature, illustrating thermosetting characteristics of epoxy resin. As the content of waterborne epoxy resin (WER) increased, there was an observed decrease in the direct tensile rate, coupled with a concurrent increase in direct tensile strength. When the ratio of emulsified asphalt and WER was 1:0.6, the tensile strength of WEREA increased by 811% in contrast to the specimen without the inclusion of WER. There existed different optimal WER contents for the pull-off strength tests conducted on different substrates. For asphalt concrete substrate and steel slab substrate, the optimum ratio of emulsified asphalt to WER + curing agent was 1:0.4, and 1:0.8 was the optimum ratio for the cement concrete substrate. When the ratio between emulsified asphalt and the combination of WER along with the curing agent was 1:0.4 (WEREA-4), the oblique shear strength obtained the maximum value, which was increased by 18.7% in contrast to WEREA-0.

Standoff-free vaporizing foil actuator welding: Process principle, experimental validation, and mechanisms analysis

This paper introduces a novel high-velocity impact welding process: the standoff-free vaporizing foil actuator welding (standoff-free VFAW). This technique employs a new type of driving mechanism, overcoming the geometric placement constraints between the flyer plate and the target plate inherent in conventional impact welding processes. It enables welding without requiring an initial standoff distance between the two plates. The feasibility and general applicability of the proposed process were validated through experiments. The welding performance was evaluated using shear tests, peel tests, and microstructural analysis. The results indicate that the proposed process can successfully weld T2 copper to 304 stainless steel and AA5083-H112 to 304 stainless steel. Additionally, this study verified that the proposed process can achieve progressive welding, making it possible to utilize standoff-free VFAW for large-area metal welding. Furthermore, microanalysis revealed the presence of a typical wavy interface characteristic at the joint. Key parameters influencing the welding results were also explored through experiments and finite element modeling, which suggest that the boundary constraints of the workpiece play a key role in the success of standoff-free VFAW. This implies that the initiation of the small and dynamic gap between the flyer and target plates could be the potential mechanism for the proposed process. In summary, standoff-free VFAW presents simplicity and efficiency as its advantages. Moreover, the insights gained from this technique are not limited solely to vaporizing foil actuator welding (VFAW) but could also provide reference points for other high-velocity impact welding techniques.

Feasibility study of carbon-fiber reinforced polymer linerless pressure vessel tank

Composite pressure vessels are used in aerospace engineering for storing fluids such as propellants, nitrogen, and oxygen. They are also used in life-support systems, High-performance pressure suits for astronauts, Helium Tanks for Balloons and Airships. Among many types of composites, Carbon fiber composites uses have been increasing due to its high strength to weight ratio, high thermal expansion, corrosion, fatigue and impact resistance and design flexibility. In order to improve the volume of the pressure vessel, the liner-less concept is tried. This increased volume efficiency is crucial in aerospace applications where space is at a premium and maximizing storage capacity within limited dimensions is important. Not only the volume efficiency, but also the Reduced Permeability Concerns, Enhanced Durability and Longevity, better thermal continuity and simplified manufacturing process make this research significant in the area of pressure vessel. This research paper deals with the fabrication and development of a cylinder without a lining. The test sample was subjected to several tests: tensile test, impact, shear test (3P Bending), leak test and Pressure test. The test sample was capable of withstanding 20 Bars without failure. The numerical results were also performed and compared with the experimental results. The difference was only 3%. Unsymmetrical dimethyl hydrazine (UDMH) AND red-fuming nitric acid can both be stored in this cylinder (RFNA). Unlike traditional composite overwrapped pressure vessels, the liner-less composite tanks rely completely on the composite shell to act as a permeation barrier as well as handling all pressure and environmental loads. The absence of a liner eliminates the potential for delamination or failure at the interface between the liner and the composite material.

Enhancing Gluten-Free Crispy Waffles with Soybean Residue (Okara) Flour: Rheological, Nutritional, and Sensory Impacts.

The incorporation of okara, a by-product of soybean milk production, into gluten-free products such as crispy waffles poses challenges due to the absence of gluten's viscoelastic properties and the high fiber content of okara. This study aimed to evaluate the effects of okara flour on the rheological properties, physical attributes, and sensory qualities of gluten-free waffles. Waffle batters with varying levels of okara flour (10%, 20%, 30%, and 40%) were prepared, and their rheological properties were analyzed using oscillatory shear and creep-recovery tests. Physical properties, proximate composition, cholesterol and glucose adsorption capacities, storage stability, and sensory attributes were also assessed. The results demonstrated that increasing okara flour content improved batter elasticity and viscosity (with complex viscosity reaching up to 10,923 Pa·s for 40% okara flour) but decreased spread ratio by up to 45% and increased moisture content by approximately 2.7%. Higher okara content also led to a 16% decrease in brightness (L*) and increased hardness, reaching 325.26 g/s at 40% substitution. Sensory evaluation revealed that waffles with 30% okara flour were preferred for their texture and overall liking, with a score of 7.43 compared to higher substitution levels. Cholesterol and glucose adsorption capacities were high in okara flour, contributing to potential health benefits. Storage stability tests showed acceptable moisture content, water activity, and microbiological safety over 60 days, though hardness decreased by about 42%. In conclusion, okara flour enhances the nutritional profile of gluten-free waffles, but its impact on texture and flavor requires careful formulation adjustments to optimize consumer acceptance.

Experimental Study on Reinforcement Properties of Tension-Resistant Reinforced Soil Retaining Wall

The tensioned reinforced soil retaining wall, a novel retaining structure, utilizes either anchors or geosynthetic materials as reinforcements that contribute to load-bearing and friction within the structure. This study aims to explore the tension distribution and strain patterns in the reinforcements, and their influence on the reinforced soil retaining walls. To this end, tensile, direct shear, and pullout tests were conducted on GeoStrap@5-50 geotextile strips and TGDG130HDPE geogrids to evaluate the tensile strength and interface strength between the reinforcement and the soil. The characteristics of the reinforcement–soil interface and the deformation behavior under stress were examined, with a comparative analysis of the technical merits of the two types of reinforcements. The results indicate that both the geotextile strips and geogrids enhanced the strength of the reinforced soil, primarily by increasing cohesion. The GeoStrap@5-50 geotextile strips exhibited superior tensile strength compared to the TGDG130HDPE geogrids; the reinforcement with the geotextile and geogrids both enhanced the cohesion of the standard sand, albeit with a slight decrease in the internal friction angle, by 4.6% and 3.1%, respectively, offering enhanced mechanical properties and economic value in reinforced soil retaining wall applications.

Bound-constrained optimization using Lagrange multiplier for a length scale insensitive phase field fracture model

The classical phase field model using the second-order geometric function α(φ)=φ2 (i.e., AT2 model), where φ∈0,1 is an auxiliary phase field variable representing material damage state, has wide applications in static and dynamic scenarios for brittle materials, but nonlinearity and inelasticity are found in its stress–strain curve. The phase field model using the linear geometric function α(φ)=φ (i.e., AT1 model), can avoid this, and a linear elastic threshold is available in its stress–strain curve. However, both AT2 and AT1 models are length scale sensitive phase field models, which could have difficulty in adjusting fracture strength and crack band simultaneously through a single parameter (the length scale). In this paper, a generalized quadratic geometric function (linear combination of AT1 and AT2 models) is used in the phase field model, where the extra parameter in this geometric function makes it a length scale insensitive phase field model. Similar to the AT1 model, negative phases can happen in the proposed generalized quadratic geometric function model. To solve this problem, a bound-constrained optimization using the Lagrange multiplier is derived, and the Karush–Kuhn–Tucker (KKT) conditions change from strain energy and maximum history strain energy (an indirect method acting on phase) to phase and Lagrange multiplier (a direct method acting on phase). Several simulations successfully validated the proposed model. A single element analysis and a bar under cyclic loading show the different stress–strain curves obtained from different models. A simulation of Mode I Brazilian test is compared with the experiment conducted by the authors, and two more simulations of Mode II shear test and mixed mode PMMA tensile test are compared with results from the literature.