Internal Stress Research Articles

Aneuploidy is Linked to Neurological Phenotypes Through Oxidative Stress.

Aneuploidy, having an aberrant genome, is gaining increasing attention in neurodegenerative diseases. It gives rise to proteotoxic stress as well as a stereotypical oxidative shift which makes these cells sensitive to internal and environmental stresses. A growing body of research from numerous laboratories suggests that many neurodegenerative disorders, especially Alzheimer's disease and frontotemporal dementia, are characterised by neuronal aneuploidy and the ensuing apoptosis, which may contribute to neuronal loss. Using Drosophila as a model, we investigated the effect of induced aneuploidy in GABAergic neurons. We found an increased proportion of aneuploidy due to Mad2 depletion in the third-instar larval brain and increased cell death. Depletion of Mad2 in GABAergic neurons also gave a defective climbing and seizure phenotype. Feeding animals an antioxidant rescued the climbing and seizure phenotype. These findings suggest that increased aneuploidy leads to higher oxidative stress in GABAergic neurons which causes cell death, climbing defects, and seizure phenotype. Antioxidant feeding represents a potential therapy to reduce the aneuploidy-driven neurological phenotype.

The novel equipment for measuring internal stress in acrylic

Acrylic is widely used in aquariums, windows of planes and submarines, and even scientific experiments like the Sudbury Neutrino Observatory (SNO) and the Jiangmen Underground Neutrino Observatory (JUNO). Internal stress has a significant impact on the properties and characteristics of acrylic such as strength, fracture and creep, which is highly concerned and has become a hotspot in research field. The measurement of internal stress is an important issue, which includes two aspects - the calibration of stress-optical coefficient of acrylic and the measurement of birefringence optical path difference (BOPD) caused by internal stress. The measuring equipment mainly realize the measurement of BOPD, and currently have the largest dynamic range of 50–3000 nm. Dynamic range is considered as one of the core performance indicators of measuring equipment, and a larger dynamic range is urgently required to meet the needs of different scenarios. The novel equipment for measuring internal stress in acrylic has been designed and developed based on photo-elastic principle and spectrometric method, which has the dynamic range of 20–12000 nm and the uncertainty of stress measurement better than 3%. The measuring principle, components, functions and measurements of the novel measuring equipment are introduced and discussed in this article.

Creep strength breakdown and the change in back stress strengthening in 10 % Cr martensitic steels during creep at 923 K

The creep strength breakdown in 10 % Cr martensitic steels appeared under creep conditions at a temperature of 923 K and the applied stresses below 120 MPa as a declination from linear regression obtained using short-term creep data. To reveal the origin of creep strength breakdown, the back stress strengthening conception was used. In the initial state, both 10 % Cr martensitic steels had a tempered martensite lath structure with a high dislocation density in the lath interiors and in the lath boundaries, which was stabilized by M23C6 carbides, NbX carbonitrides, and M6C carbides. The shear internal back stresses of 57.5–68.5 MPa and 35–37 MPa were obtained from the creep rate – stress relationship for the regions of high applied stress (above 120 MPa) and low applied stress (below 120 MPa), respectively. The transition from the high stress region to the low stress one in both steels was accompanied by a significant decrease in the dislocation density by an order of magnitude as well as a decrease in particle number density and an increase in the inter-particle spacing in the M23C6 carbide and Laves phase particles located at the low-angle boundaries of the martensitic laths/subgrains. The root mean square superposition of the dislocation and particle contributions to the shear internal back stresses gave the best coincidence with the values obtained from the creep data. The stability of the M23C6 carbide and Laves phase particles located at the low-angle boundaries was concluded to be the key factor suppressing the creep strength breakdown in the 10 % Cr martensitic steels.

A bionic mimosa soft robot based on a multi-responsive PNIPAM-PEGDA hydrogel composition.

Deformation plays a vital role in the survival of natural organisms. One example is that plants deform themselves to face the sun for sufficient sunlight exposure, which allows them to produce nutrients through photosynthesis. Drawing inspiration from nature, researchers have been exploring the development of 3D deformable materials. However, the traditional approach to manufacturing deformable hydrogels relies on complex technology, which limits their potential applications. In this study, we simulate the stress variations observed in the plant tissue to create a 3D structure from a 2D material. Using UV curing technology, we create a single-layer poly(N-isopropylacrylamide) hydrogel sheet with microchannels that exhibit distinct swelling rates when subjected to stimulation. After a two-step curing process, we produce a poly(N-isopropylacrylamide)-polyethylene glycol diacrylatedouble-layer structure that can be manipulated to change its shape by controlling the light and solvent content. Based on the double-layer structure, we fabricate a dual-response driven bionic mimosa robot that can perform a variety of functions. This soft robot can not only reversibly change its shape but also maintain a specific shape without continuous stimulation. Its capacity for reversible deformation, resulting from internal stress, presents promising application prospects in the biomedical and soft robotics domain. This study delivers an insightful framework for the development of programmable soft materials.

Ferroelectric domain structure in Bi4Ti3O12 ceramics: Insights from Confocal Raman Microscopy

Bismuth Layer-Structured Ferroelectric (BLSF) materials with Bi4Ti3O12 composition exhibit high ferroelectricity, potential for high-temperature piezoelectricity, and the puzzle of low polarizability, explored via textured ceramics and domain configurations. Here, we show that a distinctive stripe configuration of 90° domains emerges for large platelet-like grains, while the smallest grains, possessing a more equiaxial morphology, exhibit a needle-like domain structure that significantly impacts the ferroelectric properties of the ceramics. The observed hysteresis loops suggest that polarization is effectively clamped, owing to reduced mobility along the needle-like domain walls, thereby leading to a reduction in remnant polarization as grain size diminishes. It is elucidated that the domain structure is intricately linked to both internal stress within the grains and the presence of defects, notably oxygen vacancies, at the domain walls. Consequently, these multifaceted factors are identified as key determinants of the ferroelectric activity within ceramics bearing such a distinctive crystalline structure.

Magnetic leakage behavior assessment in pipeline stress-concentrated areas using improved force-magnetic coupling model.

Magnetic flux leakage (MFL) technology is remarkable for its capability to detect pipeline geometric deformation and general corrosion defects. However, it cannot characterize the MFL behavior in stress-concentrated areas, thereby greatly challenging the subsequent pipeline maintenance. This study suggests that the MFL characteristics of pipeline in stress-concentrated areas are caused by the combined effect of the face magnetic charge on the deformed end-face and the body magnetic charge of the dislocation stack. In addition, an improved force-magnetic coupling model of the pipeline in stress-concentrated areas is established based on the magnetic dipole model and Jiles-Atherton (J-A) theory. In the verification experiment, the Q235 steel plate is magnetized along the extension direction (axis of the pipeline) through the solenoid coil to obtain the distribution law of the MFL signal in the stress-concentrated area under different excitation intensities. The results show that with the increase in excitation intensity, the deformation of the MFL field signal caused by the end-face of the stress-concentrated area gradually increases to a stable state. Moreover, the internal stress of the MFL field signal generated by the pipe dislocation rapidly increases to a peak value and then decays exponentially to a certain base value. The overall change trend is in good agreement with the calculation results of the established force-magnetic coupling model. Meanwhile, the differentiation research between deformation and internal stress MFL field signals under different magnetic field intensities can provide a reliable theoretical basis for the subsequent accurate identification and quantification of pipeline stress-concentrated areas.

Shrinkage characteristics of sustainable mortar and concrete with alkali-activated slag and fly ash Binders: A focused review

Alkali-activated binders are emerging as promising sustainable alternatives to ordinary Portland cement (OPC) due to their lower environmental footprint. They offer competitive mechanical properties and enhanced durability, making them attractive options for a wide range of construction and infrastructure applications. This paper is a focused review of key findings related to the shrinkage characteristics of mortar and concrete with alkali-activated slag and fly ash binders. Shrinkage induces nonuniform deformations in mortar/concrete, leading to the development of internal tensile stresses and the formation of cracks. Such cracks may be sufficiently large to facilitate the penetration of harmful substances, which may compromise the integrity of structural elements. Several studies indicated that the combination of fly ash and slag precursors in appropriate proportions produces mortar with favorable shrinkage cracks when compared to mortar with individual binders. This article discusses the influence of the following factors on shrinkage characteristics: binder type, binder proportions, water/binder ratio, binder content, aggregate content, alkaline activator type, and concentration. The article compares the shrinkage of mortar/concrete prepared using mostly alkali-activated slag and fly ash binders and compares their shrinkage response to OPC. Shrinkage types evaluated include chemical shrinkage, autogenous shrinkage, and drying shrinkage. Shrinkage responses reported in this article include the sample curing method and environment as they are known to influence durability, strength, and shrinkage characteristics. In general, mortar/concrete with alkali-activated fly ash and slag experience higher shrinkage rates than conventional concrete with OPC binders. The study further explores shrinkage mechanisms and methods to mitigate shrinkage in alkali-activated binders.

Enhance the tribological performance of soft AISI 1045 steel through a CrN/W-DLC/DLC multilayer coating

Special equipment vehicles typically operate in complex environments, leading to wear and failure of the chassis's rotary seal shaft predominantly made of soft AISI 1045 steel. An effective approach to prolong the service life is to apply a hard coating on the working surface. Previous research have primarily concentrated on the coating for hard high-speed steel. However, the significant disparity in physical characteristics between soft AISI 1045 steel and the hard coating results in a weak interface adhesion. This study produces a CrN/W-DLC/DLC multilayer coating on the soft AISI 1045 steel with strong interfacial adhesion and superior friction and wear property through modulation of the CrN transition layer thickness. The multilayer coating consists of five layers, a CrN transition layer, a Cr layer, a Cr/WC alternating layer, a W-DLC/DLC alternating layer, and the topmost DLC layer. The thickest CrN interlayer coating achieves the Lc2 and Lc3 value of 13.9 ± 0.2 N and 20.4 ± 0.9 N. The optimized CrN/W-DLC/DLC coating reduces the internal stress of the DLC coating and enhances its adhesion. Importantly, the average friction coefficient and wear cross-sectional area of the CrN/W-DLC/DLC multilayer coatings decrease accordingly. The thickest CrN interlayer coating exhibits superior outstanding wear resistance evidenced by an average friction coefficient of 0.119, a steady-state friction coefficient of 0.097 and a wear volume of 1.508 × 106 μm3. The presence of a high proportion of sp2 bonds in the thickest CrN interlayer coating, which are susceptible to graphitization, along with a thicker transition layer that enhances the coating's support, leads to narrower wear traces. The primary wear mechanisms observed in the friction and wear test of CrN/W-DLC/DLC coatings are oxidative wear and tribo-abrasive wear. The work provides a significant promise for application in vehicle rotary seal components and a theoretical reference for enhancing the wear resistance of the seal surface.

Evaluation of pre-heated composite resins with soft-start polymerization and conventional composite restorations in class-I carious lesions – A randomized clinical trial

BackgroundBy increasing fluidity and conversion, pre-heated composites enhance adaptability and strength, while soft-start polymerization decreases internal stresses. AimOver a period of a year, this split-mouth design, randomized controlled clinical trial (RCT) compared pre-heated composites with soft-start polymerization to conventional composites in class-I lesions, with the goal of improving restoration outcomes. Methodsand Findings: Immediately following ethical approval and registration with CTRI, 37 patients with in-formed permission who met specified inclusion and exclusion criteria for class-I lesions were chosen for enrollment. Using a 1:1 ratio, teeth were randomly assigned to Group-A (pre-heated composite with soft-start polymerization) or Group-B (traditional composite restoration). At three-time intervals, the evaluation was blinded and calibrated using Modified United States Public Health Service (USPHS) criteria: baseline, six-month, and one-year marks. Statistical analysis was performed using SPSS 21.0 and the Mann-Whitney U test for inter-group comparisons and the Friedman test for intra-group comparisons. InterpretationPre-heated composites with soft-start polymerization performed better in terms of marginal adaptation with a statistically significant difference (p = 0.019) and in terms of color match they performed better clinically (p = 0.062) at 12 months. Other variables like marginal discolouration, sec-ondary caries, anatomic form, post-operative sensitivity, surface texture and retention showed no statistically significant difference (p < 0.05). Pre-heated composites with soft-start mode performed marginally better than nanofilled composites. However, both techniques can be used to successfully restore simple class-I carious lesions.

Effect of nano-silica modified resin on the interface strength and toughness of Al/CFRP hybrid laminates

In order to improve the interfacial strength and toughness of aluminum alloys and CFRP (carbon fiber reinforced plastics) hybrid laminates, modified resin with lower porosity was prepared by adding nano silica treated with silane coupling agent into epoxy resin. Al/CFRP hybrid laminates with modified resin were prepared by physical liquid deposition method and hot-press process. The strength and toughness of Al/CFRP hybrid laminates with modified resin were evaluated by tensile shear test and end notch fracture (ENF) test. The experimental results showed that the interfacial shear strength of Al/CFRP hybrid modified resin laminates is 18.8 ± 0.8 MPa and the fracture energy is 1546.33 ± 10.26 J /m2, which is 28.76 % and 15.38 % higher than that of Al/CFRP hybrid laminates with raw resin, respectively. The well-dispersed silicon nanoparticles effectively mitigate internal stress during the cross-linking process of the modified resin, thereby diminishing the dimensions of microcracks within the modified resin. The transition layer of the modified resin interface formed a cooperative and smooth structure. This structure can ensure that the transition of elements in the interface layer is smooth, and it is not easy to cause stress concentration. The formation of new bonds (C-Si bonds) at the interface of the modified resin indicates an enhancement of bonding strength at the interface, superimposing upon van der Waals forces, thereby enhancing the adhesive strength of the modified resin interface.

Analysis of bullet impact test on aluminum alloy plates at varying thickness and velocities

Analysis of bullet impact test on aluminum alloy plates at varying thickness and velocities

Study of hydraulic cutting as a method to prevent coal burst disasters

This study explores the causes of coal bursts in the Xinzhou Kiln Mine, identifying key factors such as residual pillars, hard coal seams and/or roofs, stress concentration due to complex geological structures, and the stress distribution characteristics of the primary rock. A significant finding is that hydraulic cutting not only diminishes and redistributes the stress concentration region inside the coal seam but also mitigates the burst potential of the coal-rock mass, fundamentally reducing the likelihood of coal bursts. By taking Face No. 8937 in Xinzhou Kiln Mine as the test object, a coal burst prevention test was performed using hydraulic cutting. In combination with theoretical analysis and numerical simulation, the mechanism of hydraulic cutting for preventing coal burst was discussed, and reasonable cutting parameters were established. Onsite monitoring revealed that hydraulic cutting disrupts the integrity of the coal-rock mass, releases internal stress, and increases its water content, thereby weakening its burst tendency. Additionally, the deformation and fracturing of the cutting slots and the closure of boreholes shifted the stress concentration from the coal seam to deeper areas and to the two ribs. Post-cutting observations showed a significant reduction in both the frequency and impact energy of coal bursts; there was also a noticeable increase in the convergence of the roadway in the cutting area compared to non-cutting areas. Furthermore, displacement of the roof and floor increased by 78.9 % and that of the two ribs increased by 47.4 % after cutting, preventing the coal-rock mass from accumulating high stress. In conclusion, hydraulic cutting is a promising method for effectively preventing coal bursts and enhancing the safety of mining operations.

Study on the heat treatment of multispectral ZnS for residual stress reduction

Multispectral ZnS (M − ZnS) will inevitably introduce stresses during the chemical vapor deposition (CVD) polycrystalline growth and hot isostatic pressing (HIPping) stages. In this paper, the generation mechanism and elimination method of residual stresses in M − ZnS are analyzed by means of SEM, transmittance, XRD analysis and mechanical property characterization, and the effects of heat treatment temperature, time and material annealing structure on the apparent morphology, optical and mechanical properties of M − ZnS materials are investigated. The results show that the internal stresses of M − ZnS mainly originate from the CVD ZnS growth and HIPping stages, and the most effective method to reduce the stresses is heat treatment. The key factors affecting the effect of heat treatment include temperature, time, and annealing structure. Selecting a GZ(G) annealing structure combined with a suitable cooling rate for heat treatment of M − ZnS materials will significantly improve the heat treatment effect. More annealing time has a significant effect on the transmittance in the 0.38–3 μm band, and insignificant effect on the transmittance in the 3–5 μm and 8–10 μm bands. Heat treatment will bring some degree of structural changes to the material, often manifested including a trace of hexagonal phase structure, which will affect the optical imaging quality of the window material. Heat treatment contributes to secondary grain growth, with an increase in grain size and a decrease in grain boundaries. Excessive heat treatment accelerates the loss of hardness and bending strength, and also leads to the generation of micro-cracks and macro-cracks in the material, reducing the mechanical properties of the material. Heat treatment holding 200 h and 100 h compared to the unannealed, Vickers hardness decreased by 13.518 and 7.96, respectively, bending strength decreased by 4.77 MPa and 1.73 MPa, respectively. Therefore, in actual production, should not be selected excessive heat treatment time.

The negative effect of V content on high temperature oxidation resistance of austenitic stainless steels at 850 °C

The effect of V on the high-temperature oxidation performance of austenitic stainless steel has been investigated by the constant-temperature oxidation weight gain approach, while the morphology, composition and elemental distribution of the oxide film are further analyzed by scanning electron microscopy and energy dispersive spectrum, transmission electron microscope and X-ray powder diffractometer as well as X-ray photoelectron spectroscopy, revealing the mechanism of the effect of V on the high-temperature oxidation performance of austenitic stainless steel. As a result, the addition of V has a significant adverse effect on the oxidation resistance of steel. Noteworthy, vanadium pentoxide generated during the oxidation process increases the internal stress of the surface oxide layer, reduces the integrity of the oxide layer and promotes oxygen penetration into the matrix. Simultaneously, the Z-phase formed at the grain boundaries of the matrix inhibits the diffusion of Cr ions, resulting in the inability to form an effective protective layer of Cr2O3 oxidation on the surface.

A phase field approach to the fracture simulation of quasi-brittle structures with initial state

To solve the simulation problem of crack propagation in solid structures with initial stress, this paper proposes a phase field approach that considers the initial state of the quasi-brittle structure. By using the initial equilibrium iteration method, the estimated initial state of the structure, including initial stress, is transformed into internal stress loads of the structure. Thus, the problem of non-convergence caused by inaccurate initial state estimation of the structure in engineering calculations was solved, and an improved subproblem staggered iteration method was adopted to simulate crack propagation of the structure under external loads. The universality and computational accuracy of this method for different phase field models were verified by using pre made notched thin plates for the expansion of mode I and II cracks in different initial states. Among them, the calculation error using the PF_CZM model is within 1%, and the calculation error of the AT2 model increases with the initial stress, but is less than 7%. At the same time, the crack growth problem of cracked structures under different uniform initial stresses is accurately simulated, which reflects the applicability of this method to actual engineering. In addition, the study also verified the universal applicability of the adaptive refinement strategy proposed based on the AT2 model for other phase field models.

On the interfacial behavior of two-dimensional decagonal quasicrystal films with an adhesive layer due to thermal misfit

The interfacial behavior of a thin two-dimensional decagonal quasicrystal (QC) film bonded to a half plane with an adhesive layer is analyzed under thermal misfit. Under a perfect non-slipping contact condition at interface, a theoretical model is established based on the membrane assumption, with the governing integral–differential equations being constructed in terms of phonon interfacial shear stresses in one single and multiple films. Then, these governing equations are numerically solved by Chebyshev polynomials, obtaining the phonon interfacial shear and internal normal stresses as well as the longitudinal displacement in the QC film. Finally, the effects of neighboring films, material mismatch, adhesive layer, the geometry of QC film, and temperature variation are briefly discussed on the interfacial response. It is found that the adhesive layer plays as a softening medium which can greatly reduce the value of normal and shear stresses and weaken the singularity of shear stresses near the ends of films. These findings will be instructive to the accurate measurement and safety monitoring of QC films.

The mechanism on surface integrity and fatigue performance of double‐sided micro‐cutting enhanced FeCoCrNiAl0.6 high entropy alloy

AbstractThis study examines the impact of cutting parameters on the fatigue properties of FeCoCrNiAl0.6 high‐entropy alloy under bi‐directional micro‐cutting. Utilizing Abaqus/fe−safe for analysis, we evaluated surface roughness, internal stress distribution, and fatigue longevity. Enhanced cutting speed resulted in smoother surfaces, whereas increased cut depth intensified surface roughness. Optimal cutting at 60,000 mm/min and 40 μm depth yielded a notable 91% rise in compressive stress (207 MPa) compared to slower speeds (108 MPa at 30,000 mm/min). Yield strength remained stable at 700 MPa across conditions. Fatigue resistance improved post‐bi‐directional cutting, with a 21.8–26.6% boost in life cycles, highlighting a consistent 10% advantage over single‐direction cutting.

Vibration analysis of active composite structures embedded with long and short shape memory alloy (SMA) fibers

The shape memory effect (SME) is a source of internal compressive stresses that modify the vibration behavior of shape memory alloy (SMA) embedded composite structures. Generally, long fibers are used due to their suitability for activating SMA using resistive heating. Longer SMA fibers embedded in composite structures have their limitations in design and manufacturing. Minimal research work has been done on tuning the vibration behavior of composite structures embedded with short SMA fibers. In this research paper, an analytical model for evaluating the natural frequencies of an SMA embedded composite beam has been proposed. Effects of various design parameters for long (continuous) and short (discontinuous) SMA fibers embedded in composites have been investigated. It was observed that short SMA fibers with a higher aspect ratio can tune their frequencies similarly to long SMA fiber composites and are more effective in thicker beams. Matrix material with negative coefficient thermal expansion is more suitable for embedding SMA for modifying natural frequency in active mode.

Structural design of a smart under‐deck cable‐stayed prestressed concrete viaduct: Theoretical basis and application to the Osormort viaduct

AbstractUnder‐deck cable‐stayed systems have been extensively used in bridges to optimize the internal stress distribution, enhancing their structural performance. Although these systems provide highly contribute to counteract permanent loads, their efficiency to withstand live loads is reduced, thereby limiting opportunities for material savings. This effect is particularly relevant in concrete viaducts, where the relative stiffness of the deck with respect to the tendons is very high. This limitation can be overcome by using a smart under‐deck cable‐stayed system, which gradually modifies the tension in the stays as the live load increases, improving its performance. The smart behavior is achieved through the use of a linear actuator that replaces the midspan strut of a conventional under‐deck cable‐stayed bridge. This article starts by presenting the theoretical considerations on the structural design of these innovative systems. Then, the application of this technology to multi‐span prestressed concrete bridges is evaluated using a numerical analysis. Specifically, the Osormort viaduct has been selected as a reference bridge for comparison purposes. This work quantifies the performance of the smart systems from different perspectives, including material quantities, CO2 emissions, and cost, for different portions of the live load compensated by the smart system. The comparisons reveal that the implementation of a smart system can optimize material quantity of the deck (concrete volume and internal prestressing), resulting in cost reductions of up to 15% and carbon emissions reductions of up to 9% compared to a conventional solution. In summary, this investigation provides a further confirmation of the potential of smart cable‐stayed under‐deck systems to significantly improve the structural performance of bridges while reducing material usage and costs.

Investigation of the Additional Powder Effect on the Strength of Joined Aluminum Alloy Plates in Friction Stir Welding Using the Topsis-Game Theory Model

Friction stir welding (FSW) is a process that can join many materials by causing minimal internal stress without the need for a direct electric current, contrary to traditional welding methods. The effects of SiC and Al2O3 reinforcing powders on the joining of AA6061-T6 and AA7075-T6 plates, which are difficult to join with conventional welding methods by FSW, are investigated in this study. The metallurgical properties of the combined samples are examined in terms of strength characteristics to investigate the effects of the reinforcement powder. In addition, elemental analysis is carried out for the mixing behavior of the powders. Finally, we used the TOPSIS method to select the most appropriate powder types to improve welding quality. Furthermore, a game theory application is presented to determine which powder type is suitable considering the joined aluminum plate’s strength expectations.