Increase In Compressive Stress Research Articles

Gear contact fatigue prediction under mixed elastohydrodynamic lubrication with ellipsoidal asperity rough surface: Experimental and numerical investigation

A three-dimensional(3D) line-contact mixed lubrication model and contact fatigue life prediction model for gears are established, considering the elastoplastic contact of ellipsoidal asperities and their interactions. The localized lubrication states across the actual 3D rough surfaces are visually depicted. The direct asperity contact pressures calculation exhibits greater accuracy and universality. The proposed mixed lubrication model can be applied accurately and efficiently to heavy-load conditions. The synergistic mechanisms of multi-scale surface integrity parameters, such as surface morphology-lubrication coupling, hardness gradient, and residual stress, on gear contact fatigue has been revealed. The results reveal that surface roughness significantly affects the competitive failure mechanism between surface-initiated micropitting and subsurface-initiated macropitting. The increase in surface compressive residual stress is more sensitive to the enhancement of near-surface and subsurface fatigue lives, compared to the increase of peak residual stress and the depth of peak residual stress. The proposed physics-based gear contact fatigue life prediction model has been validated through gear contact fatigue experiments under various operating conditions. The maximum deviation between the predicted and experimental fatigue lives is within 10%. This paper presents theoretical methodologies and data-driven support for optimizing the design and manufacturing processes of gears, specifically focusing on enhancing anti-fatigue properties.

Compressive stress reduction in sputter-deposited yttrium aluminum nitride (Y0.2Al0.8N) thin films for BAW resonators with high electromechanical coupling

In the past decade, rare earth elements have found increasing interest in enhancing the piezoelectric coefficient of aluminum nitride (AlN) thin films. Until now, scandium has been the most successful rare earth element to enhance the piezoelectric coefficient (d33) up to 600 %. In this research paper, we present a 250 % increase in d33 to 12.5 pC/N for sputter-deposited yttrium alloyed aluminum nitride (Y0.2Al0.8N) thin films compared to pure AlN. However, this increase in d33 comes with a substantial increase in compressive layer stress well above 1 GPa. Therefore, a chamber pressure sweep technique is introduced, resulting in a 40 % reduction in the stress level without significantly affecting the crystallographic film parameters to facilitate device integration. Even more, high compressive stress in thin films is a critical concern in piezoelectric MEMS devices such as bulk acoustic wave (BAW) resonators, as it can adversely affect the piezoelectric material properties and hence, the electromechanical performance. For this purpose, we demonstrate that the pressure sweep technique improves the electromechanical coupling factor of Y0.2Al0.8N to 7.02 %, being substantially above the reference value of 6.02 % set by pure AlN. In summary, the findings from this study may stimulate further effort to integrate YxAl1-xN thin films in BAW filter devices for future telecommunication applications.

Evaluating mechanical and biological responses of bipolymeric drug-chitosan-hydroxyapatite scaffold for wound created during sport training: Fabrication, characterization, and finite element analysis

This study aims to explore the potential of a scaffold composed of drug-chitosan-hydroxyapatite (HA) in improving tissue treatment. The focus of the investigation lies in analyzing the physical and biological properties of the scaffold and evaluating its mechanical characteristics through finite element analysis. To synthesize microcapsules containing dextran-diclofenac sodium, the electrospraying method was employed. The drug-chitosan-HA scaffold with varying volume fractions (VF) of the synthesized microcapsules (10, 15, and 20) was fabricated using the freeze-drying technique. Microscopic and scanning electron microscopy (SEM) images were utilized to evaluate the morphology, shape, and size of the microcapsules, as well as the porosity of the scaffolds for wound healing purposes. The mechanical properties of the synthesized microcapsules were determined via a nanoindentation test, while the mechanical behavior of the fabricated scaffolds was assessed through compression testing. Additionally, a multiscale finite element model was developed to predict the mechanical properties of tissue scaffolds containing pharmaceutical microcapsules. The findings indicate that the incorporation of drug-chitosan-hydroxyapatite into the tissue significantly enhances both mechanical and biological responses. The mechanical evaluations demonstrate that the drug-chitosan-hydroxyapatite tissue exhibits excellent resistance to pressure, making it a suitable protective covering for skin wounds. Moreover, biological evaluations reveal that an increase in scaffold porosity leads to higher swelling behavior, with the scaffold containing 20 % pharmaceutical microcapsules demonstrating the greatest swelling and desirable antibacterial properties, thereby indicating its potential as an effective wound dressing. Furthermore, a multiscale finite element model was developed to predict the mechanical properties of tissue containing pharmaceutical microcapsules. The results indicated that the average size of the microcapsules was in the range of 170 to 180 µm, and the porosity of the prepared tissue was between 52 % and 61 %. The experimental compressive properties revealed that an increase in the volume fraction of the embedded microcapsules led to an increase in the maximum compressive stress and compressive modulus of the scaffolds by up to 54.95 % and 53.18 %, respectively, for the scaffold containing 20 % VF of pharmaceutical microcapsules compared to the specimen containing 10 % VF. In conclusion, the developed scaffold has the potential to serve as an effective wound dressing, with the ability to provide structural support, facilitate controlled drug release, and promote wound healing.

Investigation the effect of surface treatment on the mechanical properties of coating

AbstractThe study analyzed surface treatment's impact on mechanical properties of Fe-based amorphous coatings. Specimens underwent six-hour treatments at 670 and 770 °C using vacuum heat. Results revealed distinct mechanical features in the coating: Vickers hardness reached 755, scanning electron microscope images displayed glassy phases, showcasing good wear resistance and compressive residual stresses at around −55 MPa. A remarkable 122% increase in compressive residual stress was noted through combined vacuum heat treatment and sandblasting. Volume wear decreased from the initial 18 to 14 mm3 after treatment at 670 °C followed by sandblasting, indicating a 30% enhancement in wear resistance. Yet, using vacuum heat treatment at 770 °C negatively impacted the coating's properties.

Mechanical properties of steel fiber reinforced recycled concrete under compression-shear stress state

The continuous urbanization of construction has led to an increasing demand for concrete, resulting in large-scale gravel and river sand mining, which seriously affect the sustainable development of the environment. The waste concrete produced by the demolition of old buildings is processed into recycled aggregate to replace natural aggregate, and then the preparation of recycled concrete can effectively alleviate this problem. This paper investigates the mechanical properties of steel fiber reinforced recycled concrete (SFRRAC) under compression shear conditions, a compression shear test with 99 cubic specimens was designed, with the variation parameters being recycled aggregate concrete replacement rate, compressive stress, and steel fiber content. The failure mode of SFRRAC under compression-shear stress was observed, and the shear force-displacement curve was calculated. Furthermore, a thorough examination was performed to assess the mechanical characteristics of SFRRAC specimens under compression-shear stress. The findings of this study suggest that as the compressive stress increases, the failure characteristics of the specimens shift from exhibiting brittle failure to displaying ductile failure. The shear strength is most sensitive to the change in compressive stress. When the compressive stress reaches 6 MPa, the shear strength can reach 3.41 times that of the direct shear specimen. The shear strength of SFRRAC specimens is composed of the bond strength of concrete, shear expansion strength, and friction shear strength. The incorporation of steel fibers can modify the distribution of shear strength among the individual components. The adverse effect of the recycled aggregate replacement rate on the toughness index of the specimen is mainly concentrated after the peak point. Nevertheless, an elevation in compressive stress and the inclusion of steel fibers can counterbalance this detrimental influence. The shear strength calculation formula of SFRRAC in shear state is put forward, which has a reference value. This study provides an experimental reference and a theoretical basis for further examination of SFRRAC.

Impact of Date-Palm Fibers on Fine Soil’s Compaction and Strength Properties

This paper investigates the influence of date-palm fibers on the compaction and strength properties of fine soil. The laboratory tests, including specific gravity, compaction tests, and unconfined compression strength tests, were conducted, integrating different proportions (ranging from 0 to 2%) of date-palm fibers into the soil mixture. The palm fibers were divided into two distinct lengths (30 mm and 60 mm) to be mixed with the soil. Nine samples were prepared with varying proportions of date-palm fibers for the experimental investigation, aiming to specifically examine the influences exerted by both palm-fiber length and palm-fiber content on the soil's compaction and strength characteristics when mixed with date-palm fibers. The compaction test results demonstrate a decrease in the dry unit weight and an increase in the optimum moisture content by approximately 10%. Additionally, the length of the date-palm fibers impacts the optimum moisture content and the maximum dry unit weight of the soil mixture. In contrast, the unconfined compressive stress increased by about 30% with higher date-palm fiber contents. This increase in unconfined compressive stress due to increased date-palm fiber content is a significant finding, indicating improved soil strength. This finding holds the enhancing construction performance, sustainability, and cost-efficiency. In conclusion, this soil-fiber mixture shows suitable hydraulic applications. The utilization of natural materials in civil engineering demands the exploration of available natural fibers.

Mechanical behaviors of ballastless track under temperature and vehicle loads in high geo-temperature tunnel

To explore the temperature field, temperature effect and mechanical behaviors of the track structure under combined load in high geo-temperature tunnel, the temperature field test platform is built to simulate the conditions under which the track bottom is heated in high geo-temperature tunnel, and the temperature distribution of the track bed slab in the transverse, longitudinal, and vertical directions is investigated. Then, the numerical model is built to examine the displacement and stress of the track structure under temperature load and combined load consisting of temperature and static vehicle load. The results show that when the temperature load on the track bottom is 30 ℃, the vertical temperature gradient inside the slab is negative, with a maximum of 20 ℃/m, and the maximum temperature differences in the vertical, transverse, and longitudinal directions are 5 ℃, 3.25 ℃ and 2 ℃, respectively. The temperature deformation of the track bed slab is manifested as sinking in the middle and warping at the edge, with the maximum tensile stress occurring in the upper-middle region and the maximum compressive stress in the lower-middle region. Under the combined load, the most unfavorable position of the vehicle load is where the front wheel is in the center of the slab, and for every 5 tons increase in axle load, the maximum tensile stress of the slab increases by about 4%, and the maximum compressive stress increases by about 2%. The findings provide reference for the optimization design of track in high geo-temperature tunnel.

Improvement in 3D printability, rheological and mechanical properties of pea protein gels prepared by plasma activated microbubble water

Three-dimensional (3D) food printing is one of the emerging processing technologies that enables the construction of complex food structures and customization. Although various food ingredients have been explored for their 3D printability, pea protein is among the plant proteins that have not been studied extensively on its 3D printability, owing to its native inability to hold shape and structure following extrusion. This study investigated the effect of plasma activated microbubble (PAMB) treatment on the thermal gelation and 3D printability of pea protein isolate (PPI). PAMB treatments with different combinations of discharge gases (80% argon and 20% air, 90% argon and 10% air, 100% argon, and 100% air) were applied to prepare PPI suspensions. These suspensions were then heated at 85 °C for 30 and 60 min, followed by immediate cooling to prepare PPI gels. The viscoelastic measurements and mechanical properties of PPI gels indicated that this combined application was suitable for 3D printing, with a notable increase in storage modulus (G '), loss modulus (G '') and compressive stress in PPI-PAMB gels. The 3D printed PPI gels prepared using PAMB treatment exhibited better structure retention, resistance to deformation, and stability during storage. The treatment using PAMB prepared by the combination of argon and air, i.e., 80% argon and 20% air and 90% argon and 10% air, resulted in PPI gels with better rheological properties, mechanical stability, and 3D printability. Freeze drying was investigated as a possible post-3D printing processing operation to enhance the shelf life and storage stability of 3D printed PPI gels. The moisture content, water activity, and textural properties of the freeze-dried 3D printed PPI were investigated.

Optimizing texture and mechanical properties: The impact of pH-modulated metal-phenolic networks on soy protein isolate gels

This study presents the initial exploration of utilizing metal-phenolic networks (MPN) to augment the structure of soy protein isolate (SPI) gels. By employing EGCG and zinc ions to create MPN at varying pH levels (5, 7, and 9), the research investigates the impact of MPN on the texture, mechanical properties, and microstructure of SPI gels. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that MPN binds to SPI through hydrogen bonding and electrostatic interactions. The findings indicate that the incorporation of MPN significantly enhances the structure of SPI gels. It is noteworthy that the MPN at pH 5 is the most effective in enhancing rheological properties, showing a 4 to 5-fold increase in the storage modulus. Conversely, the MPN at pH 7 excels in strengthening the 3D network, which boosts the mechanical properties, leading to a 1.88-fold increase in compressive stress. Furthermore, the addition of MPN enhances the structural integrity, thermal stability, and water retention of SPI gels, showcasing the potential of MPN as an innovative reinforcement method for food protein gels.

Enhancing Bone Implants: Magnesium-Doped Hydroxyapatite for Stronger, Bioactive, and Biocompatible Applications.

Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is an inorganic material that exhibits morphology and composition similar to those of human bone tissues, making it highly desirable for bone regeneration applications. As one of the most biocompatible materials currently in use, HAp has undergone numerous attempts to enhance its mechanical strength. This research focuses on investigating the influence of magnesium (Mg) incorporation on the structural and mechanical properties of synthesized magnesium-doped hydroxyapatite (MgHAp) samples. Apart from its biocompatibility, Mg possesses a density and elasticity comparable to those of human bone. Therefore, incorporating Mg into HAp can be pivotal for improving bone formation. Previous studies have not extensively explored the structural changes induced by Mg substitution in HAp, which motivated us to revisit this issue. Hydrothermal synthesis technique was used to synthesize MgHAp samples with varying molar concentrations (x = 0, 0.5, 1.0, and 1.5). Theoretical simulation of HAp and MgHAp for obtaining 3D structures has been done, and theoretical X-ray diffraction (XRD) data have been compared with the experimental XRD data. Rietveld analysis revealed the alteration and deviation of lattice parameters with an increase in the Mg content, which ultimately affect the structure as well the mechanical properties of prepared samples. The findings revealed an increase in compressive stress and fracture toughness as the Mg concentration in the composition increased. Furthermore, using a finite-element analysis technique and modeling of the mechanical testing data, the von Mises stress distribution and Young's modulus values were calculated, demonstrating the similarity of the prepared samples to human cortical bone. Biocompatibility assessments using NIH-3T3 fibroblast cells confirmed the biocompatible and bioactive nature of the synthesized samples. MgHAp exhibits great potential for biomedical applications in the dental, orthopedic, and tissue engineering research fields.

Study of the inhibition mechanism of sapphire subsurface damage by tangential ultrasonic vibration

Ultrasonic vibration has a certain effect on the crack propagation tendency during sapphire grinding, but the mechanism of the effect on the crack propagation tendency has not yet been elucidated. In this study, tangential ultrasonic vibratory scratching and normal scratching sapphire processes were simulated using the discrete element method, and the expansion tendency of sub-surface cracks in the scratching sapphire process was analyzed in terms of cutting forces and stresses. The results of the study show that the crack depth decreases with increasing scratch speed and increases with increasing scratch depth; The greater the variation in cutting force, the greater the number of cracks formed and the crack propagation is mainly distributed near the maximum residual tensile stress; The introduction of tangential ultrasonic vibration induces a decrease in residual tensile stresses and an increase in residual compressive stresses, thus inhibiting subsurface crack propagation; The suppression of subsurface cracks becomes more pronounced as the amplitude increases. Finally, tangential ultrasonic vibratory scratching and normal scratching sapphire experiments were comparatively studied and the experimental results were in agreement with the simulation results. This study provides some theoretical guidance for the suppression of subsurface cracks in sapphire materials during the grinding process.

Improving Wear Resistance and Corrosive Resistance of Cemented Carbide for Mud Pulser Rotor by Deep Cryogenic Treatment.

Cemented carbide used in the rotor of a mud pulser is subjected to the scouring action of solid particles and corrosive mud media for a long time, which causes abrasive wear and electrochemical corrosion. To improve the wear and corrosive resistance of cemented carbide, samples with different cobalt content (WC-5Co, WC-8Co, and WC-10Co) receive deep cryogenic treatment (DCT) at -196 °C for 2.5 h. An optical metalloscope (OM) and X-ray diffractometer (XRD) are used to observe the phase changes of cemented carbides, and the XRD is also used to observe the change in residual stress on the cemented carbide's surface. A scanning electron microscope (SEM) is used to characterize the wear and electrochemical corrosion surface microstructure of cemented carbides (untreated and DCT). The results show that the DCT promotes the precipitation of the η phase, and the diffraction peak of ε-Co tends to intensify. Compared with the untreated, the wear rates of WC-5Co, WC-8Co, and WC-10Co can be reduced by 14.71%, 37.25%, and 41.01% by DCT, respectively. The wear form of the cemented carbides is mainly the extrusion deformation of Co and WC shedding. The precipitation of the η phase and the increase in WC residual compressive stress by DCT are the main reasons for the improvement of wear resistance. The electrochemical corrosion characteristic is the dissolution of the Co phase. DCT causes the corrosion potential of cemented carbide to shift forward and the corrosion current density to decrease. The enhancement of the corrosion resistance of cemented carbide caused by DCT is due to the Co phase transition, η phase precipitation, and the increase in the compressive stress of cemented carbide.

Influence of the thickness of pyrolytic carbon interphase on the mechanical behavior of SiC/(BN/PyC)/SiC composites

The composition and thickness of the interphase are critical factors affecting the strength of SiC/SiC materials. Therefore, SiC/(BN/PyC)/SiC ceramic matrix composites with varying PyC thicknesses were fabricated, and the mechanism by which thickness influences the mechanical properties of the materials was investigated. During the fracture process of the composites, debonding and crack deflection predominantly occurred at the BN/PyC interface. The PyC interphase thickness emerged as a critical factor influencing the mechanical performance of composites. The residual stresses within the PyC and its adjacent SiC matrix were determined by analyzing shifts in Raman peak positions. The findings indicate that a reduction in PyC thickness leads to an increase in residual compressive stress within the PyC and a corresponding increase in residual tensile stress within the SiC matrix, which increases the interfacial shear stress and improves the mechanical properties of the composites.

Cyclic shear test and finite element analysis of TRC-reinforced damaged confined masonry walls

Due to the low level of seismic fortification during construction, masonry walls are highly vulnerable to earthquakes, but some walls remain in service after repair. To investigate the strengthening effect of textile-reinforced concrete (TRC) on the seismic performance of seismically damaged confined masonry (CM) walls, tests were conducted on four masonry walls, and a finite element model was established for parametric analysis. A TRC facing improves the overall performance of the wall and increases the ductility of the wall. TRC reinforcement technology increases the peak load of CM walls by 19.9%-21.7%, the ductility factor by 42.1%-52.8%, and the cumulative energy dissipation by 95%-118%. The more severe the damage to the wall is, the less effective the strengthening effect of the TRC reinforcement. As the number of layers of textile increases, the load-bearing capacity, deformation capacity and energy dissipation capacity of the walls increase. When the vertical compressive stress increases, the increase in the shear bearing capacity and energy dissipation of walls due to the TRC facings first decreases and then increases. Moreover, TRC facings have limited effectiveness in reinforcing walls with high aspect ratios and high mortar strengths.

Effect of Low to High Pressure on the Structural, Mechanical, Electrical, and Optical Properties of Inorganic Material Ca3AsBr3: An Ab Initio Investigation.

Inorganic metal halide solar cells made from perovskite stand out for having outstanding efficiency, cheap cost, and simple production processes and recently have generated attention as a potential rival in photovoltaic technology. Particularly, lead-free Ca3AsBr3 inorganic materials have a lot of potential in the renewable industry due to their excellent qualities, including thermal, electric, optoelectronic, and elastic features. In this work, we thoroughly analyzed the stress-driven structural, mechanical, electrical, and optical properties of Ca3AsBr3 utilizing first-principles theory. The unstressed planar Ca3AsBr3 compound's bandgap results in 1.63 eV, confirming a direct bandgap. The bandgap within this compound could have changed by applying hydrostatic stress; consequently, a semiconductor-to-metallic transition transpired at 50 GPa. Simulated X-ray diffraction further demonstrated that it maintained its initial cubic form, even after external disruption. Additionally, it has been shown that an increase in compressive stress causes a change of the absorption spectra and the dielectric function with a red shift of photon energy at the lower energy region. Because of the material's mechanical durability and increased degree of ductility, demonstrated by its stress-triggered mechanical characteristics, the Ca3AsBr3 material may be suitable for solar energy applications. The mechanical and optoelectronic properties of Ca3AsBr3, which are pressure sensitive, could potentially be advantageous for future applications in optical devices and photovoltaic cell architecture.

Loading Mode-Induced Enhancement in Friction for Microscale Graphite/Hexagonal Boron Nitride Heterojunction.

Classical friction laws traditionally assume that the friction between solid pairs remains constant with a given normal load. However, our study has unveiled a remarkable deviation from conventional wisdom. In this paper, we discovered that altering the loading mode of micro graphite flakes led to significant changes in the lateral friction under identical normal loads. By adding a cap onto a single graphite flake to disperse the normal load applied by an atomic force microscope (AFM) tip, we were able to distribute the concentrated force. Astonishingly, our results demonstrated a notable 4-7 times increase in friction as a consequence of load dispersion. Finite element analysis (FEA) further confirmed that the increase in compressive stress at the edges of the graphite flake, resulting from load dispersion, led to a significant increase in friction. This study underscores the critical role of the loading mode in microscale friction dynamics, challenging the prevailing notion that friction remains static with a given normal force. Importantly, our research sheds light on the potential for achieving macroscale structural superlubricity (SSL) by assembling microscale SSL graphite flakes by using a larger cap.

ZrO2/SiO2/C nanofiber aerogels with enhanced mechanical and thermal insulation properties fabricated by freeze casting

Because of the inherent high-temperature resistance, the application of ZrO2 nanofiber aerogels in thermal insulation is promising. However, the contradiction between mechanical and thermal insulation properties has limited its applications. In the present work, nanofiber aerogels of ZrO2/SiO2/C with enhanced thermal insulation and compressive strength were successfully prepared by freeze-casting using tetraethoxysilane (TEOS) as a binder. The effect of TEOS content on the microstructure, compressive and thermal insulation properties was investigated. The porosity of the fabricated aerogels is higher than 97.3 %. The pore structure exhibits hierarchical characteristics, with honeycomb pores on the micro-scale and mesopores on the nano-scale. Part of the SiO2 phases generated by TEOS hydrolysis bond ZrO2 nanofiber to form fiber junctions, while the others cover the surface of ZrO2 nanofibers forming core-shell structure. With the increase of TEOS content, ZrO2/SiO2/C nanofiber aerogels showed a slightly decrease in thermal conductivity to a lower value of 0.032 W m−1 K−1 and an increase in compressive stress to 11.9 KPa. The thermal insulation mechanism and deformation mode during compression of aerogels were analyzed. This study not only provide ZrO2/SiO2/C nanofiber aerogels with both enhanced mechanical and thermal insulation properties, but also can guide the design and fabrication of other ceramic aerogels with excellent properties.

Effect of residual volume after surgery of the discoid lateral meniscus on tibiofemoral joint biomechanics: a finite element analysis

BackgroundThe purpose of this study was to investigate the influence of different residual meniscus volume on the biomechanics of tibiofemoral joint after discoid lateral meniscus (DLM) surgery by finite element analysis.MethodsA knee joint model was established based on CT and MRI imaging data. The DLM model was divided into five regions according to conventional meniscectomy, with volumes of 15%, 15%, 15%, 15%, 15%, and 40% for each region. Additionally, the DLM model was divided into anterior and posterior parts to obtain ten regions. The DLM was resected according to the design scheme, and together with the intact discoid meniscus, a total of 15 models were obtained. Finite element analysis was conducted to assess shear and pressure trends on the knee joint.ResultsThe study observed significant changes in peak shear stress and compressive stress in the lateral meniscus and lateral femur cartilage. As the meniscus volume decreased, there was an increase in these stresses. Specifically, when the meniscus volume reduced to 40%, there was a sharp increase in shear stress (302%) and compressive stress (152%) on the meniscus, as well as shear stress (195%) and compressive stress (157%) on the lateral femur cartilage. Furthermore, the model grouping results showed that preserving a higher frontal volume in the meniscus model provided better biomechanical advantages.ConclusionThe use of finite element analysis has demonstrated that preserving more than 55% of the meniscus volume is necessary to prevent a significant increase in joint stress, which can potentially lead to joint degeneration. Additionally, it is crucial to preserve the front volume of the DLM in order to achieve improved knee biomechanical outcomes.

Study on mechanical and degradation behavior of Zn–Mn-xMg alloys under coupling effects of stress and SBF

Zinc-based implants will be subjected to combination of physiological corrosive media and stress during service in vivo. In this study, the mechanical and degradation behavior of Zn–Mn-xMg alloys under coupling effects of stress and simulated body fluid (SBF) were investigated. As a result, the ultimate tensile strength of Zn–Mn-xMg alloys decreased and incline to brittle fracture under the condition of slow strain rate tensile test in SBF. In addition, at a slower strain rate (1 × 10−6 s−1), the stress corrosion cracking susceptibility value will increase with the rise of Mg content. The immersion test under different compressive stresses shows that the corrosion will be inhibited under high pressure stress (50 MPa) compared with the lower one (10 MPa). The residual compressive strength of Zn-0.8Mn-xMg alloys decreases after immersion. A dense oxide layer could be induced with the increase of compressive stress, and it would inhibit the corrosion of the Zn-0.8Mn-xMg matrixes. These results indicate that Zn-0.8Mn-xMg alloys are expected to be a promising biodegradable material for biomedical applications.

Numerical simulation analysis of anchor pullout under radial pressurization of anchor solid

The rock structure of weak rock formation is loose with low strength, which is easy to deform. Due to insufficient elongation and bearing capacity, anchor anchorage system damage is frequent and serious. Given the above problems, this paper researches the radial increase in compressive stress anchoring mechanism and uses finite element software ABAQUS simulation algorithms to obtain different radial pressurization conditions under the deformation of the surrounding rock law and the anchor pulling the anchor and the surrounding rock displacement stress change rule. The results show that when applying the radial pressure of 1.5 MPa, the surrounding rock and the anchor stress reach their maximum value, and the displacement reaches its minimum value. Field testing and monitoring results show that radial pressurized anchors can effectively control the deformation of the roadway perimeter rock and improve the anchoring effect.