Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Search Results (361)

Search Parameters:
Keywords = softening or plasticizing

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
23 pages, 5966 KiB  
Article
Study on Mechanism and Constitutive Modelling of Secondary Anisotropy of Surrounding Rock of Deep Tunnels
by Kang Yi, Peilin Gong, Zhiguo Lu, Chao Su and Kaijie Duan
Symmetry 2025, 17(8), 1234; https://doi.org/10.3390/sym17081234 - 4 Aug 2025
Abstract
Crack initiation, propagation, and slippage serve as the key mesoscopic mechanisms contributing to the deterioration of deep tunnel surrounding rocks. In this study, a secondary anisotropy of deep tunnels surrounding rocks was proposed: The axial-displacement constraint of deep tunnels forces cracks in the [...] Read more.
Crack initiation, propagation, and slippage serve as the key mesoscopic mechanisms contributing to the deterioration of deep tunnel surrounding rocks. In this study, a secondary anisotropy of deep tunnels surrounding rocks was proposed: The axial-displacement constraint of deep tunnels forces cracks in the surrounding rock to initiate, propagate, and slip in planes parallel to the tunnel axial direction. These cracks have no significant effect on the axial strength of the surrounding rock but significantly reduce the tangential strength, resulting in the secondary anisotropy. First, the secondary anisotropy was verified by a hybrid stress–strain controlled true triaxial test of sandstone specimens, a CT 3D (computed tomography three-dimensional) reconstruction of a fractured sandstone specimen, a numerical simulation of heterogeneous rock specimens, and field borehole TV (television) images. Subsequently, a novel SSA (strain-softening and secondary anisotropy) constitutive model was developed to characterise the secondary anisotropy of the surrounding rock and developed using C++ into a numerical form that can be called by FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions). Finally, effects of secondary anisotropy on a deep tunnel surrounding rock were analysed by comparing the results calculated by the SSA model and a uniform strain-softening model. The results show that considering the secondary anisotropy, the extent of strain-softening of the surrounding rock was mitigated, particularly the axial strain-softening. Moreover, it reduced the surface displacement, plastic zone, and dissipated plastic strain energy of the surrounding rock. The proposed SSA model can precisely characterise the objectively existent secondary anisotropy, enhancing the accuracy of numerical simulations for tunnels, particularly for deep tunnels. Full article
(This article belongs to the Section Engineering and Materials)
Show Figures

Figure 1

27 pages, 1561 KiB  
Article
The Effect of a Pectin Coating with Gamma-Decalactone on Selected Quality Attributes of Strawberries During Refrigerated Storage
by Gabriela Kozakiewicz, Jolanta Małajowicz, Karolina Szulc, Magdalena Karwacka, Agnieszka Ciurzyńska, Anna Żelazko, Monika Janowicz and Sabina Galus
Coatings 2025, 15(8), 903; https://doi.org/10.3390/coatings15080903 (registering DOI) - 2 Aug 2025
Viewed by 195
Abstract
This study investigated the effect of an apple pectin coating enriched with gamma-decalactone (GDL) on the physicochemical and microbiological quality of strawberries over 9 days of refrigerated storage. Strawberries were coated with pectin solutions containing a plasticizer and emulsifier, with or without GDL, [...] Read more.
This study investigated the effect of an apple pectin coating enriched with gamma-decalactone (GDL) on the physicochemical and microbiological quality of strawberries over 9 days of refrigerated storage. Strawberries were coated with pectin solutions containing a plasticizer and emulsifier, with or without GDL, and compared to uncoated controls. The coatings were evaluated for their effects on fruit mass loss, pH, extract content (°Brix), firmness, color parameters (L*, a*, b*, C*, h*, ΔE), and microbial spoilage. The pectin coating limited changes in extract, pH, and color and slowed firmness loss. Notably, GDL-enriched coatings significantly reduced spoilage (14.29% after 9 days vs. 57.14% in the control) despite accelerating pulp softening. Extract content increased the most in the GDL group (from 9.92 to 12.00 °Brix), while mass loss reached up to 22.8%. Principal Component Analysis (PCA) confirmed coating type as a major factor differentiating sample quality over time. These findings demonstrate the potential of bioactive pectin-based coatings to enhance fruit preservation and support the development of active packaging strategies. Further studies should optimize coating composition and control the release kinetics of functional compounds. Full article
(This article belongs to the Special Issue Preparation and Applications of Bio-Based Polymer Coatings)
Show Figures

Graphical abstract

29 pages, 7048 KiB  
Article
Research on Synergistic Control Technology for Composite Roofs in Mining Roadways
by Lei Wang, Gang Liu, Dali Lin, Yue Song and Yongtao Zhu
Processes 2025, 13(8), 2342; https://doi.org/10.3390/pr13082342 - 23 Jul 2025
Viewed by 195
Abstract
Addressing the stability control challenges of roadways with composite roofs in the No. 34 coal seam of Donghai Mine under high-strength mining conditions, this study employed integrated methodologies including laboratory experiments, numerical modeling, and field trials. It investigated the mechanical response characteristics of [...] Read more.
Addressing the stability control challenges of roadways with composite roofs in the No. 34 coal seam of Donghai Mine under high-strength mining conditions, this study employed integrated methodologies including laboratory experiments, numerical modeling, and field trials. It investigated the mechanical response characteristics of the composite roof and developed a synergistic control system, validated through industrial application. Key findings indicate significant differences in mechanical behavior and failure mechanisms between individual rock specimens and composite rock masses. A theoretical “elastic-plastic-fractured” zoning model for the composite roof was established based on the theory of surrounding rock deterioration, elucidating the mechanical mechanism where the cohesive strength of hard rock governs the load-bearing capacity of the outer shell, while the cohesive strength of soft rock controls plastic flow. The influence of in situ stress and support resistance on the evolution of the surrounding rock zone radii was quantitatively determined. The FLAC3D strain-softening model accurately simulated the post-peak behavior of the surrounding rock. Analysis demonstrated specific inherent patterns in the magnitude, ratio, and orientation of principal stresses within the composite roof under mining influence. A high differential stress zone (σ1/σ3 = 6–7) formed within 20 m of the working face, accompanied by a deflection of the maximum principal stress direction by 53, triggering the expansion of a butterfly-shaped plastic zone. Based on these insights, we proposed and implemented a synergistic control system integrating high-pressure grouting, pre-stressed cables, and energy-absorbing bolts. Field tests demonstrated significant improvements: roof-to-floor convergence reduced by 48.4%, rib-to-rib convergence decreased by 39.3%, microseismic events declined by 61%, and the self-stabilization period of the surrounding rock shortened by 11%. Consequently, this research establishes a holistic “theoretical modeling-evolution diagnosis-synergistic control” solution chain, providing a validated theoretical foundation and engineering paradigm for composite roof support design. Full article
Show Figures

Figure 1

23 pages, 1856 KiB  
Article
Comparative Evaluation of Gelatin and HPMC Inhalation Capsule Shells Exposed to Simulated Humidity Conditions
by Sabrina Magramane, Nikolett Kállai-Szabó, Dóra Farkas, Károly Süvegh, Romána Zelkó and István Antal
Pharmaceutics 2025, 17(7), 877; https://doi.org/10.3390/pharmaceutics17070877 - 3 Jul 2025
Viewed by 616
Abstract
Background/Objectives: This study investigates the impact of high humidity (25 °C, 75% relative humidity) on gelatin and hydroxypropyl methylcellulose (HPMC) capsules used in dry powder inhalers (DPIs), focusing on moisture dynamics, structural responses, and mechanical performance, with an emphasis on understanding how [...] Read more.
Background/Objectives: This study investigates the impact of high humidity (25 °C, 75% relative humidity) on gelatin and hydroxypropyl methylcellulose (HPMC) capsules used in dry powder inhalers (DPIs), focusing on moisture dynamics, structural responses, and mechanical performance, with an emphasis on understanding how different capsule types respond to prolonged exposure to humid conditions. Methods: Capsules were exposed to controlled humidity conditions, and moisture uptake was measured via thermal analysis. Visual observations of silica bead color changes were performed to assess moisture absorption, while surface wettability was measured using the sessile drop method. Hardness testing, mechanical deformation, and puncture tests were performed to evaluate structural and mechanical changes. Positron annihilation lifetime spectroscopy (PALS) was used to analyze free volume expansion. Results: HPMC capsules exhibited rapid moisture uptake, attributed to their lower equilibrium moisture content and ability to rearrange dynamically, preventing brittleness. In contrast, gelatin capsules showed slower moisture absorption but reached higher equilibrium levels, resulting in plasticization and softening. Mechanical testing showed that HPMC capsules retained structural integrity with minimal deformation, while gelatin capsules became softer and exhibited reduced puncture resistance. Structural analysis revealed greater free volume expansion in HPMC capsules, consistent with their amorphous nature, compared with gelatin’s semi-crystalline matrix. Conclusions: HPMC capsules demonstrated superior humidity resilience, making them more suitable for protecting moisture-sensitive active pharmaceutical ingredients (APIs) in DPI formulations. These findings underline the importance of appropriate storage conditions, as outlined in the Summary of Product Characteristics, to ensure optimal capsule performance throughout patient use. Full article
(This article belongs to the Section Physical Pharmacy and Formulation)
Show Figures

Graphical abstract

18 pages, 3861 KiB  
Article
Investigating the Rheological Impact of USP Warm Mix Modifier on Asphalt Binder
by Yali Liu, Jingfei Ping, Hao Guo, Yikai Kang and Yali Ye
Coatings 2025, 15(7), 784; https://doi.org/10.3390/coatings15070784 - 3 Jul 2025
Viewed by 440
Abstract
USP (usual temperature pitch)-modified asphalt optimizes its rheological properties through reactions between the modifier and the asphalt. This significantly enhances the high- and low-temperature adaptability and environmental friendliness of asphalt. It has now become an important research direction in the field of highway [...] Read more.
USP (usual temperature pitch)-modified asphalt optimizes its rheological properties through reactions between the modifier and the asphalt. This significantly enhances the high- and low-temperature adaptability and environmental friendliness of asphalt. It has now become an important research direction in the field of highway engineering. This article systematically investigates the impact of different dosages of USP warm mix modifier on asphalt binders through rheological and microstructural analysis. Base asphalt and SBS-modified asphalt were blended with USP at varying ratios. Conventional tests (penetration, softening point, ductility) were combined with dynamic shear rheometry (DSR, AASHTO T315) and bending beam rheometry (BBR, AASHTO T313) to characterize temperature/frequency-dependent viscoelasticity. High-temperature performance was quantified via multiple stress creep recovery (MSCR, ASTM D7405), while fluorescence microscopy and FTIR spectroscopy elucidated modification mechanisms. Key findings reveal that (1) optimal USP thresholds exist at 4.0% for base asphalt and 4.5% for SBS modified asphalt, beyond which the rutting resistance factor (G*/sin δ) decreases by 20–31% due to plasticization effects; (2) USP significantly improves low-temperature flexibility, reducing creep stiffness at −12 °C by 38% (USP-modified) and 35% (USP/SBS composite) versus controls; (3) infrared spectroscopy displays that no new characteristic peaks appeared in the functional group region of 4000–1300 cm−1 for the two types of modified asphalt after the incorporation of USP, indicating that no chemical changes occurred in the asphalt; and (4) fluorescence imaging confirmed that the incorporation of USP led to disintegration of the spatial network structure of the control asphalt, explaining the reason for the deterioration of high-temperature performance. Full article
(This article belongs to the Special Issue Surface Treatments and Coatings for Asphalt and Concrete)
Show Figures

Figure 1

14 pages, 8148 KiB  
Article
Effect of Temperature on the Low-Cycle Fatigue Behavior of Polycrystalline TiAl Alloys
by Junyan Zhou, Haochuan Zhao, Pei Li and Henggao Xiang
Materials 2025, 18(13), 3147; https://doi.org/10.3390/ma18133147 - 2 Jul 2025
Viewed by 278
Abstract
In this paper, the low-cycle fatigue deformation behavior of polycrystalline γ-TiAl alloys at different temperatures was investigated by molecular dynamics simulations. The results showed that the fatigue process comprises an initial cyclic softening stage followed by saturation, and the stress–strain response of the [...] Read more.
In this paper, the low-cycle fatigue deformation behavior of polycrystalline γ-TiAl alloys at different temperatures was investigated by molecular dynamics simulations. The results showed that the fatigue process comprises an initial cyclic softening stage followed by saturation, and the stress–strain response of the material shows significant asymmetry. With an increase in temperature, the asymmetry between tensile and compressive stresses gradually decreases, and the amplitude of saturated stress decreases significantly. The decrease in dislocation density leads to the cyclic softening of the alloy, and the evolution of dislocation density is temperature-dependent. The dislocation density first decreases and then tends to be stable, while at 900 °C and 1000 °C, it shows an abnormal trend of decreasing first and then increasing. In addition, microscopic mechanism analysis shows that grain coarsening, dislocation annihilation, and phase instability lead to the cyclic softening of the alloys. The fatigue plastic accumulation at low temperatures is mainly dominated by dislocation slip, while at high temperatures, grain boundary slip gradually replaces dislocation slip and becomes the main deformation mechanism. This work reveals new insights into the mechanical behavior of polycrystalline γ-TiAl alloys under cyclic plasticity and temperature-dependent deformation mechanisms. Full article
(This article belongs to the Section Metals and Alloys)
Show Figures

Figure 1

20 pages, 6844 KiB  
Article
Influence of Water Immersion on Coal Rocks and Failure Patterns of Underground Coal Pillars Considering Strength Reduction
by Haihua Zhu, Peitao Wang, Kewei Zhang, Yijun Gao, Zhenwu Qi and Meifeng Cai
Appl. Sci. 2025, 15(12), 6700; https://doi.org/10.3390/app15126700 - 14 Jun 2025
Viewed by 356
Abstract
The long-term immersion of coal rock may affect its mechanical properties and failure modes, potentially impacting the stability of coal pillars. This work aims to investigate the influence of the immersion duration on the mechanical properties and fracture evolution processes of coal, employing [...] Read more.
The long-term immersion of coal rock may affect its mechanical properties and failure modes, potentially impacting the stability of coal pillars. This work aims to investigate the influence of the immersion duration on the mechanical properties and fracture evolution processes of coal, employing acoustic emission detection and the digital image correlation (DIC) method. The work focuses on the weakening law of the coal pillar dam in contact with water and obtains a model of the strength deterioration after different periods of water immersion. The stress–strain curves of coal specimens with varying immersion durations are obtained. The results show that the peak absorption rate of coal samples immersed in water transpires within 24 h, with fundamental saturation being achieved at between 25 and 30 days at saturation moisture content of 1.97%. The specimen’s compressive stress after being immersed in water for 7 days is 3.34 MPa, with strain of 0.18%. The cracking stress is 15.60 MPa, with strain of 0.54%. The peak stress is recorded at 27.65 MPa, with strain of 0.92%. The complete rupture stress measures 23.37 MPa, with the maximum strain at 0.95%. During the yielding stage, the specimen has the highest strain increment of 0.38%. Short-term immersion brings about an increase in the coal sample’s plasticity, exhibiting a relatively minor softening impact of water, resulting in comparatively intact fragmentation and modest breakage. A negative exponential function relationship is observed between the compressive strength of coal and the immersion duration. The mechanical reduction relationship is utilized to analyze the failure patterns of coal pillars in underground reservoirs. With prolonged water immersion, the damage area expands to include the coal pillars and the surrounding rock of the excavation area. Full article
Show Figures

Figure 1

12 pages, 1701 KiB  
Article
Effects of Hydration on the Mechanical Properties of Salt-Doped Poly(methyl methacrylate)
by Asae Ito, Naoki Uchida, Yusuke Hiejima and Koh-hei Nitta
Molecules 2025, 30(12), 2568; https://doi.org/10.3390/molecules30122568 - 12 Jun 2025
Viewed by 343
Abstract
The mechanical performance of poly(methyl methacrylate) (PMMA) is highly sensitive to moisture absorption, which induces plasticization and softening. In this study, we investigated the ductilization mechanism of PMMA by incorporating various metal salts with different cations (Li+ and Mg2+) and [...] Read more.
The mechanical performance of poly(methyl methacrylate) (PMMA) is highly sensitive to moisture absorption, which induces plasticization and softening. In this study, we investigated the ductilization mechanism of PMMA by incorporating various metal salts with different cations (Li+ and Mg2+) and controlling water absorption through hygroscopic interactions. A nonequilibrium constitutive model is introduced, in which localized water domains around salt-rich regions gradually diffuse into the PMMA matrix during tensile deformation. The stress–strain behavior is described by combining rigid (dry) and soft (hydrated) matrix components, connected through an internal kinetic variable governed by the strain-dependent diffusion rate. The model successfully reproduces experimental tensile data and captures the transition from brittle to ductile behavior as a function of the moisture content. Notably, Mg salts exhibit stronger water binding and slower moisture redistribution than Li salts, resulting in distinct mechanical responses. These findings provide a mechanistic framework for tailoring the ductility of hygroscopic polymer systems via ion–water–polymer interactions. Full article
Show Figures

Figure 1

24 pages, 5486 KiB  
Article
Revealing the Influence of Material Properties of Shaped Charge Liner on Penetration Performance via Numerical Simulation and Machine Learning
by Yan Wang, Jinxu Liu, Xingwei Liu, Xinya Feng, Yifan Du and Jie Cao
Materials 2025, 18(12), 2742; https://doi.org/10.3390/ma18122742 - 11 Jun 2025
Viewed by 409
Abstract
The metallic shaped charge liner (SCL) is widely utilized in the defense industry, oil perforation, cutting, and other industrial fields due to the powerful penetration performance. However, quantitative law and underlying mechanisms of material properties affecting SCL penetration performance are unclear. Based on [...] Read more.
The metallic shaped charge liner (SCL) is widely utilized in the defense industry, oil perforation, cutting, and other industrial fields due to the powerful penetration performance. However, quantitative law and underlying mechanisms of material properties affecting SCL penetration performance are unclear. Based on the real and virtual material properties, by combining numerical simulation with machine learning, the influence of material properties on SCL penetration performance was systematically studied. The findings in the present work provided new insights into the penetration mechanism and corresponding influencing factors of the metal jet. It indicated that penetration depth was dominated by the melting point, specific heat, and density of the SCL materials rather than the conventionally perceived plasticity and sound velocity. Average perforation diameter was dominated by the density and plasticity of the SCL materials. Particularly, the temperature rise and thermal softening effect of the SCL controlled by the melting point and specific heat have a significant effect on the “self-consumption” of the metal jet and further on the penetration ability. Additionally, the density of the SCL influences the penetration depth deeply via dynamic pressure of the jet, but the influence of density on penetration depth decreases with the increase in density. The correlation between the key properties and penetration performance was obtained according to a quadratic polynomial regression algorithm, by which the penetration potential of SCL materials can be quantitatively evaluated. Overall, the present study provides a new SCL material evaluation and design method, which can help to expand the traditional penetration regime of the SCL in terms of the penetration depth and perforation and is expected to be used for overcoming the pierced and lateral enhancement trade-off. Full article
(This article belongs to the Section Materials Simulation and Design)
Show Figures

Figure 1

15 pages, 3488 KiB  
Article
Prediction of Large Springback in the Forming of Long Profiles Implementing Reverse Stretch and Bending
by Mohammad Reza Vaziri Sereshk and Hamed Mohamadi Bidhendi
J. Exp. Theor. Anal. 2025, 3(2), 16; https://doi.org/10.3390/jeta3020016 - 6 Jun 2025
Viewed by 313
Abstract
Springback represents the deflection of a workpiece after releasing the forming tools or dies, which influences the quality and precision of the final products. It is basically governed by the elastic strain recovery of the material after unloading. Most approaches only implement reverse [...] Read more.
Springback represents the deflection of a workpiece after releasing the forming tools or dies, which influences the quality and precision of the final products. It is basically governed by the elastic strain recovery of the material after unloading. Most approaches only implement reverse bending to determine the final shape of the formed product. However, stretch plays significant role whe the blank is held by a blank holder. In this paper, an algorithm is presented to calculate the contributions of both stretch loads and bending moments to elastic deformation during springback for each element, and to combine them mathematically and geometrically to achieve the final shape of the product. Comparing the results of this algorithm for different sheet metal forming processes with experimental measurements demonstrates that this technique successfully predicts a wide range of springback with reasonable accuracy. The advantage of this approach is its accuracy, which is not sensitive to hardening and softening mechanisms, the magnitude of plastic deformation during the forming process, or the size of the object. The application of the proposed formulation is limited to long profiles (plane-strain cases). However, it can be extended to more general applications by adding the effect of torsion and developing equations in 3D space. Due to the explicit nature of the calculations, data-processing time would be reduced significantly compared to the sophisticated algorithms used in commercial software. Full article
Show Figures

Figure 1

19 pages, 10561 KiB  
Article
Environmental Effects of Moisture and Elevated Temperatures on the Mode I and Mode II Interlaminar Fracture Toughness of a Toughened Epoxy Carbon Fibre Reinforced Polymer
by Anna Williams, Ian Hamerton and Giuliano Allegri
Polymers 2025, 17(11), 1503; https://doi.org/10.3390/polym17111503 - 28 May 2025
Cited by 1 | Viewed by 623
Abstract
The use of composite materials within extreme environments is an exciting frontier in which a wealth of cutting-edge developments have taken place recently. Although there is vast knowledge of composites’ behaviour in standard room temperature and humidity, there is a great need to [...] Read more.
The use of composite materials within extreme environments is an exciting frontier in which a wealth of cutting-edge developments have taken place recently. Although there is vast knowledge of composites’ behaviour in standard room temperature and humidity, there is a great need to understand their performance in ‘hot/wet’ conditions, as these are the conditions of their envisaged applications. One of the key failure mechanisms within composites is interlaminar fracture, commonly referred to as delamination. The environmental effects of moisture and elevated temperatures on interlaminar fracture toughness are therefore essential design considerations for laminated aerospace-grade composite materials. IM7/8552, a toughened epoxy/carbon fibre reinforced polymer, was experimentally characterised in both ‘Dry’ and ‘Wet’ conditions at 23 °C and 90 °C. A moisture uptake study was conducted during the ‘Wet’ conditioning of the material in a 70 °C/85% relative humidity environment. Dynamic mechanical thermal analysis was carried out to determine the effect of moisture on the glass transition temperature of the material. Mode I initiation and propagation fracture properties were determined using double cantilevered beam specimens and Mode II initiation fracture properties were deduced using end-notched flexure specimens. The effects of precracking and the methodology of high-temperature testing are discussed in this report. Mode I interlaminar fracture toughness, GIC, was found to increase with elevated temperatures and moisture content, with GIC=0.205kJ/m2 in ‘Dry 23 °C’ conditions increasing by 26% to GIC=0.259kJ/m2 in ‘Wet 90 °C’ conditions, demonstrating that the material exhibited its toughest behaviour in ‘hot/wet’ conditions. Increased ductility due to matrix softening and fibre bridging caused by temperature and moisture were key contributors to the elevated GIC values. Mode II interlaminar fracture toughness, GIIC, was observed to decrease most significantly when moisture or elevated temperature was applied individually, with the combination of ‘hot/wet’ conditions resulting in an 8% drop in GIIC, with GIIC=0.586kJ/m2 in ‘Dry 23 °C’ conditions and GIIC=0.541kJ/m2 in ‘Wet 90 °C’ conditions. The coupled effect of fibre-matrix interface degradation and increased plasticity due to moisture resulted in a relatively small knockdown on GIIC compared to GIC in ‘hot/wet’ conditions. Fractographic studies of the tested specimens were conducted using scanning electron microscopy. Noteworthy surface topography features were observed on specimens of different fracture modes, moisture saturation levels, and test temperature conditions, including scarps, cusps, broken fibres and river markings. The qualitative features identified during microscopy are critically examined to extrapolate the differences in quantitative results in the various environmental conditions. Full article
Show Figures

Graphical abstract

23 pages, 4958 KiB  
Article
Influence of Deformation Temperature and Strain Rate on Martensitic Transformation of Duplex Stainless Steel and Its Corresponding Kinetic Model
by Qiyong Zhu, Fei Gao, Zilong Gao, Weina Zhang, Shuai Tang, Xiaohui Cai and Zhenyu Liu
Metals 2025, 15(6), 581; https://doi.org/10.3390/met15060581 - 24 May 2025
Cited by 1 | Viewed by 544
Abstract
For investigating the effect of temperature and strain rate on martensitic transformation and establishing the corresponding kinetic model for newly TRIP (transformation-induced plasticity) aided duplex stainless steel (DSS), the tensile tests are conducted at temperatures of 20–150 °C and strain rates of 0.0001–150 [...] Read more.
For investigating the effect of temperature and strain rate on martensitic transformation and establishing the corresponding kinetic model for newly TRIP (transformation-induced plasticity) aided duplex stainless steel (DSS), the tensile tests are conducted at temperatures of 20–150 °C and strain rates of 0.0001–150 s−1. The stepped cross-section tensile specimen is proposed and designed for obtaining microstructure at specific strain during dynamic tensile testing. The results demonstrate that the deformation mechanism of austenite in TRIP-aided DSS is highly sensitive to temperature and strain rate. As the deformation temperature increases, strain-induced martensitic transformation is inhibited, and the deformation mechanism transforms from martensitic transformation to the co-occurrence of martensitic transformation and twinning, and finally, twinning is the main deformation mechanism. This leads to reduced strength with an initial increase followed by a decrease in elongation. As the strain rate increases, martensitic transformation is inhibited, resulting in a reduction in strength and plasticity during quasi-static tensile testing, while during dynamic tensile testing, strength increases due to enhanced resistance to dislocation motion, and plasticity displays no significant variation because of the combination of adiabatic softening and martensitic transformation suppression. Moreover, during tensile deformation, a plastic temperature rise model is established for newly developed DSSs. Based on this model, the Ludwigson–Berger model for martensitic transformation was modified to couple the effect of temperature and strain rate by considering the non-uniform distribution of temperature rise within the material and its variation with strain rate, as well as the suppression of dynamic strain rate on martensitic transformation. This new model could accurately describe the characteristics of martensitic transformation in newly developed DSSs at different deformation temperatures and strain rates. Full article
(This article belongs to the Special Issue Microalloying Mechanism of Ferritic Stainless Steel)
Show Figures

Figure 1

15 pages, 5003 KiB  
Article
Softening of Production Tubing Under Random Vibration Excitation and Prediction of Fatigue Life of the Entire Wellbore
by Lian Liu, Zhongwei Huang, Peng Su, Yinping Cao and Yihua Dou
Processes 2025, 13(5), 1495; https://doi.org/10.3390/pr13051495 - 13 May 2025
Viewed by 380
Abstract
A study was conducted on the mechanical behavi or of the completion string in a 10,000 m ultra-deep well from western China’s oilfields to identify the causes of plastic failure in the string. This article analyzes the interaction between fluid and tubing in [...] Read more.
A study was conducted on the mechanical behavi or of the completion string in a 10,000 m ultra-deep well from western China’s oilfields to identify the causes of plastic failure in the string. This article analyzes the interaction between fluid and tubing in high-pressure and high-production gas wells by establishing a fluid structure coupling four-equation model. Through fatigue tests, it was found that P110 tubing material has a stress amplitude related ratchet effect, revealing the softening characteristics of tubing material. Through case analysis, the fatigue of the entire wellbore was analyzed, and it was shown that the fatigue hotspot is concentrated near the neutralization point, and stress concentration under high-production and low-production conditions leads to the degradation of tubing material performance under fatigue load. After continuous service for 30 days under high-production and low-production conditions, the entire wellbore section exhibited a softening phenomenon, and the yield strength began to decrease below 4349 m and 4324 m well depths, respectively. The safety factor of the entire wellbore section decreased. Within 284 days of production, the fatigue damage of the entire wellbore section was less than 5%, and the remaining yield change and material softening of the tubing string were negligible. However, there was an impact load during the lifecycle, which caused severe fluctuations in the wellbore safety factor and was the main cause of tubing string fracture. Subsequent research should integrate diverse well cases exhibiting varying production parameters to establish a statistically robust predictive framework for safety factor variations. Full article
(This article belongs to the Section Materials Processes)
Show Figures

Figure 1

26 pages, 46466 KiB  
Article
Experimental Investigation of Mechanical Properties and Pore Characteristics of Hipparion Laterite Under Freeze–Thaw Cycles
by Tengfei Pan, Zhou Zhao, Jianquan Ma and Fei Liu
Appl. Sci. 2025, 15(9), 5202; https://doi.org/10.3390/app15095202 - 7 May 2025
Viewed by 499
Abstract
The Loess Plateau region of China has an anomalous climate and frequent geological disasters. Hipparion laterite in seasonally frozen regions exhibits heightened susceptibility to freeze–thaw (F-T) cycling, which induces progressive structural weakening and significantly elevates the risk of slope instability through mechanisms including [...] Read more.
The Loess Plateau region of China has an anomalous climate and frequent geological disasters. Hipparion laterite in seasonally frozen regions exhibits heightened susceptibility to freeze–thaw (F-T) cycling, which induces progressive structural weakening and significantly elevates the risk of slope instability through mechanisms including pore water phase transitions, aggregate disintegration, and shear strength degradation. This study focuses on the slip zone Hipparion laterite from the Nao panliang landslide in Fugu County, Shaanxi Province. We innovatively integrated F-T cycling tests with ring-shear experiments to establish a hydro-thermal–mechanical coupled multi-scale evaluation framework for assessing F-T damage in the slip zone material. The microstructural evolution of soil architecture and pore characteristics was systematically analyzed through scanning electron microscopy (SEM) tests. Quantitative characterization of mechanical degradation mechanisms was achieved using advanced microstructural parameters including orientation frequency, probabilistic entropy, and fractal dimensions, revealing the intrinsic relationship between pore network anisotropy and macroscopic strength deterioration. The experimental results demonstrate that Hipparion laterite specimens undergo progressive deterioration with increasing F-T cycles and initial moisture content, predominantly exhibiting brittle deformation patterns. The soil exhibited substantial strength degradation, with total reduction rates of 51.54% and 43.67% for peak and residual strengths, respectively. The shear stress–displacement curves transitioned from strain-softening to strain-hardening behavior, indicating plastic deformation-dominated shear damage. Moisture content critically regulates pore microstructure evolution, reducing micropore proportion to 23.57–28.62% while promoting transformation to mesopores and macropores. At 24% moisture content, the areal porosity, probabilistic entropy, and fractal dimension increased by 0.2263, 0.0401, and 0.0589, respectively. Temperature-induced pore water phase transitions significantly amplified mechanical strength variability through cyclic damage accumulation. These findings advance the theoretical understanding of Hipparion laterite’s engineering geological behavior while providing critical insights for slope stability assessment and landslide risk mitigation strategies in loess plateau regions. Full article
Show Figures

Figure 1

25 pages, 12927 KiB  
Article
Experimental and Numerical Analysis of Freeze–Thaw-Induced Mechanical Degradation in the Coarse-Grained Soil of the Southeastern Qinghai–Xizang Plateau
by Huan Niu, Peiqing Wang, Liang Chen, Ding Sang, Chao Li, Congyou Shi and Wengang Zhang
Appl. Sci. 2025, 15(9), 4900; https://doi.org/10.3390/app15094900 - 28 Apr 2025
Viewed by 354
Abstract
To investigate the effects of freeze–thaw (FT) cycles on the mechanical properties of coarse-grained soil in southeastern Xizang under different moisture contents, this study focuses on coarse-grained soil from a large landslide deposit in Linzhi City, Xizang. FT cycle tests, triaxial shear tests, [...] Read more.
To investigate the effects of freeze–thaw (FT) cycles on the mechanical properties of coarse-grained soil in southeastern Xizang under different moisture contents, this study focuses on coarse-grained soil from a large landslide deposit in Linzhi City, Xizang. FT cycle tests, triaxial shear tests, and numerical simulations were employed to systematically examine the comprehensive impact of varying FT cycles, moisture content, and confining pressure on the soil’s mechanical characteristics. The results show that FT cycles significantly affect the stress–strain behavior of coarse-grained soil in southeastern Xizang. The degree of strain softening increased from approximately 11.6% initially to 31.2% after 15 FT cycles, with shear strength decreasing by an average of 31.8%. Specifically, cohesion decreased by 38% to 55% after 0 to 15 FT cycles, and the internal friction angle decreased by approximately 29% to 32%. Additionally, higher moisture content led to more pronounced strain softening and strength degradation, while increased confining pressure effectively mitigated these deteriorative effects. Numerical simulation results indicated that as moisture content increased from 7.6% to 11.6%, the number of FT cycles required to reach the critical instability state decreased from approximately 150 to 106, and finally to only 15, with the maximum equivalent plastic strain increasing from 0.20 to 2.47. The findings of this study provide key mechanical parameters for understanding the formation and evolution of FT landslide disasters in southeastern Xizang and lay a scientific foundation for the assessment and long-term prevention of cold-region geological hazards. Full article
Show Figures

Figure 1

Back to TopTop