Weakening Effect Research Articles

Structural evolution and mechanical response of multiple Al Σ5(210) grain boundaries with segregation of solute atoms: First-principles study

Grain boundary (GB) segregation of solute atoms is a key factor affecting the microstructure and macroscopic properties of materials. In this study, first-principles calculations were carried out to investigate the effect of solute atoms (Mg and Cu) segregation on the structural evolution and mechanical response of Al ground-state Σ5(210) GB (GB-Ⅰ) and metastable Σ5(210) GBs (GB-Ⅱ and GB-Ⅲ). The GB energy, segregation energy, and the theoretical tensile strength of the multiple Σ5(210) GBs were calculated. The results show that both Mg and Cu atoms tend to segregate in the boundary plane, thus reducing GB energy and improving GB stability. The segregation of Cu atoms reduced the GB energy more significantly than that of Mg atoms. The segregation of solute atoms can change the symmetric GB structure into an asymmetric one or induce GB phase transformation. The theoretical strength of GB-I is weaker than that of the metastable GB-II with higher GB energy, suggesting that grain boundaries with higher energy are not necessarily unstable. In addition, the effect of solute atom segregation on the GB strength depends not only on the type of element but also on the specific GB structure. The weakening effect of Mg segregation in GB-I and GB-II is due to the weak MgAl bond which enlarges the low charge density region of GB and increases the free volume of GB. The strengthening of GB-I and GB-II by Cu segregation mainly depends on the stronger AlCu bond than AlAl bond along the GB fracture path. The enhanced strength of GB-III with Mg and Cu segregation is attributed to the GB structural phase transformation caused by the segregation of solute atoms. The calculation results further elucidate the relationship between element segregation and grain boundary characteristics.

Fault size-dependent fracture energy explains multiscale seismicity and cascading earthquakes.

Earthquakes vary in size over many orders of magnitude, often rupturing in complex multifault and multievent sequences. Despite the large number of observed earthquakes, the scaling of the earthquake energy budget remains enigmatic. We propose that fundamentally different fracture processes govern small and large earthquakes. We combined seismological observations with physics-based earthquake models, finding that both dynamic weakening and restrengthening effects are non-negligible in the energy budget of small earthquakes. We established a linear scaling relationship between fracture energy and fault size and a break in scaling with slip. We applied this scaling using supercomputing and unveiled large dynamic rupture earthquake cascades involving >700 multiscale fractures within a fault damage zone. We provide a simple explanation for seismicity across all scales with implications for comprehending earthquake genesis and multifault rupture cascades.

Influence of corrugated/flat rolling on microstructure and tensile property of coarse-grained AZ31–0.25Ca cast alloy

Novel corrugated rolling technology (CR) and conventional flat rolling (FR) were employed for rolling the AZ31–0.25Ca cast alloy without prior predeformation. The impact of corrugated rolling and/or flat rolling on texture modification, microstructure evolution, and mechanical properties of the magnesium alloy during two-pass rolling was examined using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), tensile tests at ambient temperature, and ABAQUS finite element simulation analysis. The results indicate that the AZ31–0.25Ca cast alloy, after homogenization with a coarse grain structure of ∼200 μm, can endure significant plastic deformation with a 60 % total rolling reduction in both corrugated-flat rolling (CFR) and flat-flat rolling (FFR) without experiencing edge cracking. Twinning is activated dramatically except for dislocation slip during CFR, which induced high-density dislocations piling up at the twin boundaries and grain boundaries of α-Mg grains. The CFR sheet exhibited a macroheterogeneous structure attributed to the distinctive corrugated roll profile. Elevated shear strain and intensified frictional shear stress were observed at the trough, resulting in the formation of an asymmetric cross shear band in the CFR sheet. Denser deformation twins and finer recrystallized grains are present at the trough, whereas fewer and coarser ones are observed at the peak, while there is a significant texture weakening effect for corrugated rolling in contrast to the conventional flat rolling. but the stress and strain heterogeneity and asymmetric cross shear band also induce strong stress concentration and result in a premature cleavage fracture and a lower tensile property in CFR sheet compared to that of the FFR sheet.

Assessment of Rural Industry Integration Development, Spatiotemporal Evolution Characteristics, and Regional Disparities in Ethnic Regions: A Case Study of Inner Mongolia Autonomous Region Counties

Ethnic regions in China primarily focus on the development of agricultural and animal husbandry economies, which are relatively underdeveloped. Rural industry integration development (RIID) is considered the foundation and guarantee for ethnic regions to achieve high-quality modernization of agriculture. The purpose of this article is to measure the level of rural industrial integration in ethnic minority areas, analyze the spatial evolution and regional differences, and explore the actual situation of RIID in these regions. The aim is to provide a decision-making basis for local governments to effectively promote the development of rural industrial integration. Based on the improvement of the evaluation index system for rural industrial integration development, this paper takes the counties of the Inner Mongolia Autonomous Region as the research area. Utilizing panel data from the statistical yearbooks of 68 banners and counties in Inner Mongolia from 2011 to 2020, the panel entropy weight TOPSIS method is employed to assess the average level of rural industrial integration in the research area. The ArcGIS natural breakpoint method is employed to classify the level of RIID in county areas. Exploratory Spatial Data Analysis (ESDA) and GeoDa are utilized to analyze the spatial distribution characteristics of RIID. Finally, the Theil index is employed to analyze the regional differences in the level of RIID. The results show the following: (1) The overall level of RIID in ethnic regions is relatively low, with the contributions of the four dimensions in the evaluation index system as follows: integration path > integration foundation > integration sustainability > integration effect. The level of RIID in the study area is as follows: western region > eastern region > central region. (2) Spatially, there are positive correlations and significant spatial clustering in the level of RIID, with the spatial clustering effect of RIID weakening. (3) There are regional differences in the level of RIID, which are expanding. The inter-regional differences are decreasing, while the intra-regional differences are increasing. (4) The construction of agricultural processing facilities, financial investment, financial support, and talent policies are important influencing factors for the current stage of RIID in ethnic regions. Therefore, in the low-level development stage of RIID in ethnic regions, it is necessary to fully utilize the advantages of resource endowment, increase investment in rural infrastructure, and strengthen the guidance of talent flow into rural revitalization construction.

The water weakening effect on the progressive slope failure under excavation and rainfall conditions

The water weakening effect refers to the gradual deterioration of soil mechanical properties under long-term saturation. This paper analyzed the impact of water weakening on slope stability under alternating excavation and rainfall. The field investigation speculated shale hydration as the cause of overall slope instability. The mechanical parameters of hydrated shale were determined by the parameter inversion and empirical estimation methods. The simulations were used to restore the process of parameter weakening and slope failure, and confirmed the fact that hydration causes landslide. Furthermore, the failure mechanism of slope and support structure under hydration were investigated. The results show that the mechanical parameters of the slope decreased linearly, whereas the plastic strain–time and total displacement-maximum shear stress curves of the hydrated shale exhibited three stages: slow initial growth, rapid growth in the middle term, and rapid increase in the later period; the rate of slope deformation and the factor of safety reduction also gradually increase over time; under middle stage of hydration, the middle to rear of shale were extruded, while the front first underwent tensile shear deformation, forming a plastic zone of at rear and front excavated slope; In the late stage, hydrated shale quickly reaches its yield limit (maximum shear stress of 270 kPa), the middle and rear shale is damaged and compresses the front, causing it to transform from tensile shear to compressive shear failure. The plastic zone in the rear extends forward and connects with the front ones, forming an overall landslide. Besides, preventing deep landslides caused by hydration through waterproofing, drainage, protection, and support for excavated slopes has proven difficult. Therefore, it is necessary to redesign treatment schemes based on the characteristics of stress, strain, and seepage.

A 3D coupled Material Point Method study on hydro-mechanical collapse mechanism of the tunnel face in shields with a partially filled chamber

The deterioration of groundwater seepage on the tunnel face stability is a principal risk for tunnelling through watery ground, and a thorough understanding of soil–water coupled large deformation behaviors is essential for effective disaster prevention. This study employs a three-dimensional (3D) coupled Material Point Method (MPM) to analyze the hydro-dynamical collapse characteristics of the tunnel face, particularly focusing on tunnel shields with partially filled chambers where the air pressure is utilized to support the upper portion of the tunnel face. Initially, the validity of the 3D coupled MPM is verified through comparing numerical and analytical results of a 1D consolidation problem, covering from small to large deformation analyses. Subsequently, the evolutionary characteristics of the tunnel face collapse and ground response are investigated through a series of large-scale simulations. Special attention is given to differentiate failure responses between saturated and dry sand, emphasizing the weakening effect of seepage flow on tunnel faces. Furthermore, the influence of different combinations of construction conditions and soil properties on the collapse process is also investigated. Numerical results validate the efficacy of the 3D coupled MPM in addressing hydro-dynamical tunnel face collapse issues, with goals of providing insights into associated disaster prevention and post-failure behavior prediction.

Bonding Performance and Microstructural Mechanism between Rapid Repair Materials and Old Concrete Pavement

In China, airports predominantly utilize airport cement concrete pavement, which inevitably undergoes deterioration in service. To uphold pavement durability and functionality, and ensure aircraft operational safety, prompt repairs of affected areas are imperative. Therefore, ordinary Portland cement mortars were used as the control group to compare and analyze the bonding performances of two common airport pavement repair materials: modified Portland cement mortars and phosphate cement mortars. Meanwhile, through microscopic experiments, the microscopic characteristics of the interfacial transition zone (ITZ) were studied, and the interface bonding mechanism was analyzed. The research results indicate that the interface bonding strength between phosphate cement mortar and old concrete pavement is the highest. This was because the elements in phosphate cement penetrated the old concrete pavement through hydration reactions, forming van der Waals forces and chemical bonding forces. In addition, the research results indicated that the presence of old concrete pavement made the three repair materials produce similar sidewall effects with the old concrete pavement, leading to a low hydration degree of the repair materials. However, the chemical bonding and penetrating structure of phosphate cement compensated for the weakening effect of the ITZ in the repair materials.

Coupled Effects of High Temperature and Steel Fiber Content on Energy Absorption Properties of Concrete.

The associated effects of temperature and steel fiber content on the energy absorption properties of concrete were examined using quasi-static uniaxial compression tests of concrete materials with varied steel fiber contents (0%, 0.5%, 1%, and 1.5%) at various temperatures (20 °C, 200 °C, 400 °C, and 520 °C). The experimental findings demonstrate that steel fibers can greatly boost concrete's ability to absorb energy and that the toughness index rises with steel fiber concentration. The energy absorption capacity of concrete under high-temperature conditions also significantly decreases as temperature rises, and the energy absorption ability of steel fiber concrete under the same temperature is superior to that of plain concrete. The coupled influence factor K of temperature-steel fiber percentage characterizing the energy-absorbing ability of concrete was determined, and the coupled influence law of temperature and steel fiber content on the energy-absorbing capacity of concrete materials was summarized and analyzed on the basis of the experimental data of high-temperature compression. Equivalent equations for steel fiber reinforcing and temperature weakening effects when they are comparable (K = 1) are developed and equivalent parameters for concrete materials are given.

Effects of mixing water and environmental pH value on the properties of sulfoaluminate cement-based ultra-high water materials

In order to grasp the influence of the pH value of mixing water and environmental water on the properties of ultra-high water materials, this article separately carried out the influence of different pH values of mixing water on the properties of ultra-high water materials and the conservation of high-water materials in water environments with different pH values. Using test methods such as loss of flow time, compressive strength, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Thermogravimetric-Differential Thermal Analysis (TG–DTA), to conduct regular exploration and mechanism analysis. The study found that with the continuous increase of the pH value of the mixing water, the loss of flow time of the ultra-high water material gradually decreased, and the compressive strength of the samples at the same age continued to increase. A lower pH value will affect the compressive strength of the consolidated body of the ultra-high water material, but when the pH = 13 in the reaction solution, the compressive strength of the consolidated body will no longer increase and begin to produce a weakening effect. The pH of the construction water for ultra-high water materials is recommended to be 4–13. At the same time, it was found that under the conservation of an acidic environment, the consolidated body was severely eroded and the strength loss was large. The acid–base environment of the goaf suitable for filling with the ultra-high water material should be between pH = 7–10 to ensure that the filling body is not weakened by erosion.

Toughness Evolution of Flax-Fiber-Reinforced Composites under Repeated Salt Fog-Dry Aging Cycles.

This research examined the response of flax-fiber-reinforced composites (FFRCs) to simulated outdoor conditions involving repeated exposure to salt fog and drying. The study investigated the effect of cycles on the toughness of the FFRCs. To achieve this, the composites were exposed to humidity (salt fog) for 10 days, followed by 18 days of drying in cycles. A total of up to 3 cycles, each lasting 4 weeks, were conducted over a 12-week period. Throughout this process, changes in the material's weight, water absorption, and mechanical properties were monitored by water uptake and three-point bending tests. The findings revealed the significant impact of these humid-dry cycles on the mechanical response of the FFRCs. When exposed to humid environments without drying, the composite's toughness increased significantly, due to a weakening effect more pronounced for stiffness, with strength reductions of about 20%. However, subsequent drying partially restored the material's performance. After 18 days of drying, the composite regained most of its initial performance.

The thermal transport, mechanical, and optical properties of T-Cu6S2: The influence of Cu6 clusters

Cluster substitution can effectively regulate the physicochemical properties of two-dimensional (2D) materials and has been applied in fields such as catalysis and magnetism. However, the intrinsic mechanism of its regulation of thermal transport properties and the impact of clusters on optical and mechanical properties are not yet clear. In this work, 2D T-Cu6S2 is obtained by replacing the transition metal element M of 2D T-MS2 with the Cu6 clusters. Then, based on the first-principles method, we systematically studied the thermal transport, mechanical, and optical properties of T-Cu6S2. The results show that introducing Cu6 clusters reduces the phonon vibration frequency, and enhances phonon scattering, that is, the coupling effect of harmonic weakening and anharmonic enhancement. This makes the lattice thermal conductivity of T-Cu6S2 at the four-photon level reduced to 0.18 W/mK (at 300 K), which is much lower than that of traditional 2D T-MS2. In addition, we found that the introduction of clusters changes the crystal and electronic structures of T-Cu6S2, enhances the flexibility and ductility of T-Cu6S2, and increases its transmission ability for visible light and ultraviolet light. This study provides insights into the regulation of multiple properties of 2D materials, which benefits the development of 2D functional materials.

Extreme weather characteristics and influences on urban ecosystem services in Wuhan Urban Agglomeration

In recent years, there has been a pronounced increase in the frequency of extreme weather events. To comprehensively examine the impact of extreme weather on ecosystem services within the Wuhan Urban Agglomeration (WUA), this study utilized meteorological station data, the Mann-Kendall (MK) test, and the Standardized Precipitation-Evapotranspiration Index (SPEI) to quantify the variation trends in heatwaves (HW) and droughts from 1961 to 2020. Then the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was employed to evaluate and compare the differences in water yield and climate regulation ecosystem services under various HW, droughts, and HW-drought combination scenarios. The results show that over the past 60 years, the temperature, duration, and frequency of HW have significantly increased in the WUA. Specifically, the highest HW temperature, total HW days, HW frequency, and average HW temperature showed changing trend of +0.17 ℃/decade, +1.4 day/decade, +0.19 event/decade, and +0.07 ℃/decade, respectively. The year 2000 was identified as a mutation year for HW, characterized by increased frequency and heightened severity thereafter. The SPEI value exhibited an insignificant upward trend, with 1980 marked as a mutation year, indicating a decreasing trend in drought occurrences after 1980. Heatwaves have a weakening effect on both water yield and climate regulation services, while drought significantly weakened water yield and had a relatively modest effect on climate regulation. During HW-drought composite period, the average monthly water yield showed a notable discrepancy of 60 mm compared to humid years. Besides, as heatwaves intensify, the area of low aggregation for ecosystem services expands, whereas the area of high aggregation decreases. This study provides a preliminary understanding of the impact of urban extreme weather on urban ecosystem services under changing climatic conditions.

Superior moderate-strength Pd–Pt/Al-based composite tailored for dehydrogenation of perhydroacenaphthene

Pd–Pt-based catalysts are promising for the dehydrogenation of perhydroacenaphthene (PHAN) molecules, yet their effectiveness is hampered by strong adsorption of the product C12H8 and limitations under extreme conditions. Herein, utilizing a relational model involving d-band center, sub-surface coverage, and H atom and C12H8 adsorption energies, the most dehydrogenation-prone crystal facet was identified. Following this, employing Mulliken charge and Sabatier principle, we screened positively charged Pd–Pt/111_O2(Al) surface with moderate interaction strength through the calculation of interaction energy between the chosen Pd–Pt surface and thermally stable MgAl2O4(111) terminal surfaces. Crucially, an extensive examination into reaction mechanisms, microkinetics, and the variation in interaction strength between support and active components at 873.15 K and 3 MPa was conducted. It was observed that the rate-determining step for PHAN molecules on the Pd–Pt/111_O2(Al) surface was C12H19* + * → C12H18* + H*, with a rate of 2.57 × 10-23 s−1. The dehydrogenation of C12H10 to C12H8 proved more favorable than from C12H20 to C12H10, with the latter strengthening support and active components, unlike the weakening effect of the former. This work offers essential foundational support for the development of excellent performance catalysts and the dehydrogenation process of superior heat sink fuels.

Degradation of remaining mechanical properties of bainitic 2.25Cr1Mo steel during creep

In this work, the microstructure and remaining mechanical properties of bainitic 2.25Cr1Mo steel plate used in steam generator of sodium cooled fast reactor during creep were systematically examined. Creep tests at 530 °C with a rupture time up to 18800 h reveals that the creep stress correlates linearly with the Larson-Miller parameter (PLM), while the creep plasticity is rather independent on PLM. The remaining strength parameters, such as yield strength (RP0.2), ultimate tensile strength (Rm) and hardness (H), are found to linearly decrease with PLM, while the remaining plasticity is seen to increase. It suggests that the application of creep stress to the steel accelerates the softening of the material. During the creep process, the dislocation density in bainitic matrix decreases, while the number density of carbides increases, sacrificing the solution strengthening and leading to a continual reduction in the lattice parameter. Although abundant fine carbides precipitate after creep rupture, the remaining strength is however reduced. Instead, the weakening effect due to reduction in dislocation and solute content overwhelms the strengthening of precipitation, resulting in a degradation of the remaining strength. The obtained remaining mechanical properties are attempted to be applied in the design and operation assessment of steam generator.

Computation method for mechanical performances of die-cast aluminum alloys based on non-uniform material properties

Integrated die casting is an effective method for the lightweight design of automobiles and for improving production efficiency. It has gained popularity in the field of new energy vehicles. When calculating the mechanical performances of integrated die-cast parts, engineers do not rigorously assume that material properties are uniform. This assumption ignores the influence of the size and internal defects on the mechanical properties of die-cast aluminum alloys, leading to the deviation of the calculation results from the actual material. Material properties are closely related to microstructure. To investigate the size effect and defect effect of the mechanical properties of die-cast aluminum alloys, the die-cast mold with varying wall thicknesses and flow lengths is designed. Die-cast tests, tensile experiments, and casting simulations are conducted to obtain the mechanical properties of JDA1b aluminum alloy at various thicknesses and defect rates. The microstructure of the JDA1b alloy with different defect rates and thicknesses is characterized. Results show that the yield strength, ultimate tensile strength, and elongation of the JDA1b alloy decrease as the defect rate increases. This work proposes a new mechanical constitutive model that considers defect rate and thickness and develops a computation method for mechanical performances of die-cast aluminum alloys based on non-uniform material properties. The methodology is applied to a large integrated die-cast part, and it effectively predicts the weakening effect of defects on the material properties. This work provides high-precision computational support for the mechanical performances of integrated die-cast parts containing defects.

Financial inclusion, competition and financial stability: New evidence from developing economies

This study utilizes cross-country data from 2002 to 2019 from 60 selected developing countries to explore the impact of competition and financial inclusion on financial stability. Employing the system GMM estimator, compelling evidence is revealed, highlighting a number of key findings. Firstly, it is observed that financial inclusion has a weakening effect on financial stability within developing countries. Conversely, competition among these nations demonstrates a significant capacity to bolster financial stability. Additionally, the study underscores the pivotal role of financial development, identifying it as a primary driver that enables financial inclusion to positively influence financial stability within developing nations. Furthermore, the introduction of the square term of financial inclusion yields noteworthy insights, revealing a nonlinear relationship. Specifically, the findings suggest that strategic investments in the financial inclusion of developing countries have the potential to enhance financial stability up to a certain threshold. Therefore, for emerging economies seeking to fortify their financial stability, prioritizing efforts to augment financial inclusion is imperative. Over the long term, such endeavors have the potential to yield tangible improvements in financial stability.In conclusion, the research offers valuable policy implications. These include recommendations aimed at fostering greater financial inclusion within developing economies as a means of bolstering overall financial stability. By heeding these suggestions and implementing targeted policies, policymakers can work towards cultivating a more resilient and robust financial landscape within their respective nations.

Asymmetric trading restriction and return comovement

This study decomposes the overall return comovement into intraday and overnight comovement based on a model-free framework. It shows that intraday return comovement contributes the most to the overall return comovement, but the impact of overnight return comovement is persistent. Investors under the market with asymmetric trading restrictions (ATR) tend to sell stocks early in the market and buy them near the end of the market. This correlated trading behavior contributes to the specific comovement in stock returns, especially the overnight return. Our findings remain solid even after controlling for more stock attributes and changing the proxies for return comovement and investor trading behavior. We also document a weakening (reinforcing) effect of the short-selling mechanism (disposition effect) on the ATR-induced return comovement. Our results provide a deeper understanding of investors’ trading behavior under ultra-short-term trading restrictions and the source of return comovement in the literature.

Competition between Initial CO2 Electroreduction and Hydrogen Evolution Reaction on Cu Catalysts in Acidic Media: Role of Specifically Adsorbed Halide Anions.

The role of halide anions and competing mechanisms between initial CO2 electroreduction pathways and hydrogen evolution reaction (HER) are systematically identified at halide anions modified Cu(111)/H2O interfaces based on density functional theory calculations in this paper. The present results show that halide anions modified Cu(111)/H2O interfaces can notably enhance electroreduction activity of CO2 into CO. Simultaneously, it is concluded that the specifically adsorbed halide anions modified Cu electrodes can inhibit HER by studying competing HER mechanisms, and thus the enhanced CO2 electroreduction activity can be ascribed to the suppressed HER. The origin of enhanced CO production activity and inhibited HER is further scrutinized. The present results show that the presence of halide anions can lead to stronger CO adsorption and the increased adsorption strength of CO can explain easier CO production based on the Sabatier principle. Interestingly, the calculated results show that the presence of halide anions does not exert an effect on H adsorption strength, which is regarded as a key descriptor of HER activity, implying that halide anions modified Cu electrodes may be not able to directly lead to the inhibited HER. However, the present results indicate that co-adsorbed CO can weaken adsorption strength between H and Cu electrodes and thus result in inhibited HER and decreased HER activity. The upshift of d-band centers of surface Cu atoms due to modification of halide anions may be a reason for stronger CO adsorption, whereas the downshift of the d-band center due to the presence of co-adsorbed CO can lead to a weakening effect on H adsorption strength. Our present insights into the role of halide anions can aid in designing an optimal electrolyte and developing electrocatalysts that are more selective toward CO2 electroreduction than HER.

Theoretical study on the water-induced weakening of rock based on microstructural mechanics approach

For rock structures exposed in the natural condition, water-induced weakening (including water softening and chemical weathering) is thought to be the main reason for its’ stiffness and strength degradation, thus it is of great significance to study the mechanical properties of rocks under the influence of water. In this study, a hexagonal close-packed particle assembly (2D) composed of bonded circular particles with same diameter is considered to approximate a typical soft rock, where the composite contact model for rock materials considering the water-induced wakening is adopted to define the microscopic mechanical reactions between particles. Based on homogenisation theory and lattice model, the stress-strain relationship and strength criteria for rock considering water-induced weakening, as well as the quantitative correlation between macroscopic elastic and strength parameters with microscopic parameters are obtained. The effects of water softening and chemical weathering respectively characterised by saturation and mass loss ratio on macroscopic mechanical behaviours of rock are analysed in detail. The long-term ageing effects of water-induced weakening are also analysed. All results are in good agreement with the laboratory test results, verifying the applicability of the theoretical solution for analysing the effect of water-induced weakening on mechanical behaviours of rock.

Study on the Law of Rock Drillability under High-Temperature and High-Pressure Conditions in the Western Margin of the Ordos Basin

The deep strata in the Ordos Basin exhibit characteristics of high temperature and high stress. Conventional methods for assessing drillability (normal temperature and pressure) fail to accurately understand the drilling resistance characteristics of deep rocks in this region, leading to improper guidance for selecting formation drilling tools and prolonging drilling cycles. This study employs physical experiments and numerical simulations to conduct drillability tests on core samples taken from the region under high-temperature and high-pressure conditions, simultaneously simulating the rock breaking process under different temperature and pressure conditions. The study investigates the variation patterns of rock drillability grade values and von Mises stress values during rock breaking under single-factor and multi-factor analyses of temperature and pressure conditions. Combining these variation patterns, an optimization analysis of the back rake angle of PDC drill bits used in drillability experiments is conducted to guide the selection of drill bits on site. The results indicate that the variation patterns of von Mises values from finite element simulations are consistent with the drillability grade values under high-temperature and high-pressure conditions. Under single-factor conditions, von Mises stress and drillability grade values generally increase with rising temperature before decreasing, while they increase with increasing confining pressure. Under multi-factor conditions, confining pressure is the primary influencing factor within the range of 0 to 50 MPa, while the influence of temperature becomes prominent between 180 °C to 200 °C, with a weakening effect of confining pressure. Model application: Selecting a back rake angle of 30° for PDC drill bits yields optimal rock-breaking results. The research findings hold significant implications for understanding the low rock-breaking efficiency of deep strata, optimizing drill bit parameters, and enhancing drilling efficiency.