Will greenhouse gas emissions increase with mining depth in coal mines? An analysis of gas occurrence under varying in-situ stress conditions.

The rapid development of the economy leads to the high demand for deep coal resources, which further poses the potential problem of deep gas (or methane) emissions. The clarification of deep gas occurrence law for coal mines provides theoretical and data support for methane emission predictions, and assists industrial and mining enterprises in planning targeted emission reduction measures. This study defined and verified the existence of a critical depth for the deep gas occurrence in coal mines based on a multiple-scale case study of how the gas occurrence is associated with depth and stress status changes in the Pingdingshan No.8 Coal Mine. In addition, 882 sets of gas content data from 7 major mining areas in China were collected and their gas content distributions among various depths were statistically analyzed to prove the universal existence of critical depth. The results show that the critical depth of Pingdingshan No.8 Coal Mine is 509 m, and the critical depth of other Chinese areas is about 400 to 1000 m. Significant differences were observed in the pore space, surface, and gas desorption characteristics for coal samples with different depths and stress states. The pore structure in the critical depth area is relatively developed, and gas is easily accumulated. The gas occurrence of both normal and abnormal gas gradually increases with the depth's increase in areas above the critical depth, whereas the gas occurrence gradually decreases for areas below the critical depth, showing that the existence of critical depth lead to significant deviations in gas emission predictions. The results provide a fundamental reference for gas emission prediction, greenhouse effect assessment, and carbon emission factor calculation and indicate that using the traditional linear method may be misleading for evaluating deep gas occurrence and emission.

A Hybrid EEG-Based Stress State Classification Model Using Multi-Domain Transfer Entropy and PCANet.

This paper proposes a new hybrid model for classifying stress states using EEG signals, combining multi-domain transfer entropy (TrEn) with a two-dimensional PCANet (2D-PCANet) approach. The aim is to create an automated system for identifying stress levels, which is crucial for early intervention and mental health management. A major challenge in this field lies in extracting meaningful emotional information from the complex patterns observed in EEG. Our model addresses this by initially applying independent component analysis (ICA) to purify the EEG signals, enhancing the clarity for further analysis. We then leverage the adaptability of the fractional Fourier transform (FrFT) to represent the EEG data in time, frequency, and time-frequency domains. This multi-domain representation allows for a more nuanced understanding of the brain's activity in response to stress. The subsequent stage involves the deployment of a two-layer 2D-PCANet network designed to autonomously distill EEG features associated with stress. These features are then classified by a support vector machine (SVM) to determine the stress state. Moreover, stress induction and data acquisition experiments are designed. We employed two distinct tasks known to trigger stress responses. Other stress-inducing elements that enhance the stress response were included in the experimental design, such as time limits and performance feedback. The EEG data collected from 15 participants were retained. The proposed algorithm achieves an average accuracy of over 92% on this self-collected dataset, enabling stress state detection under different task-induced conditions.

Study of Anisotropic Behavior in Sheet Metal Forming.

Since sheet metal exhibits significant anisotropy in processing and forming, which has a significant impact on its performance during processing, forming, and use, we explore the anisotropic behavior of materials in the forming process of sheet metal. The ability of the Yld2000-2d criterion to describe anisotropic behavior is analyzed, and its accuracy for characterization of the anisotropic behavior of metal plates is improved, based on which anisotropic behavior is predicted in three-dimensional space. Theoretical and experimental results on the anisotropy of sheet metal are compared, and two materials, 5754O aluminum alloy and DP980 steel plate, are tested and analyzed, and the anisotropic behaviors, such as three-point bending and cylindrical deep-drawing, are well predicted.

Experimental Study of the Implantation Process for Array Electrodes into Highly Transparent Agarose Gel.

Brain-computer interface (BCI) technology is currently a cutting-edge exploratory problem in the field of human-computer interaction. However, in experiments involving the implantation of electrodes into brain tissue, particularly high-speed or array implants, existing technologies find it challenging to observe the damage in real time. Considering the difficulties in obtaining biological brain tissue and the challenges associated with real-time observation of damage during the implantation process, we have prepared a transparent agarose gel that closely mimics the mechanical properties of biological brain tissue for use in electrode implantation experiments. Subsequently, we developed an experimental setup for synchronized observation of the electrode implantation process, utilizing the Digital Gradient Sensing (DGS) method. In the single electrode implantation experiments, with the increase in implantation speed, the implantation load increases progressively, and the tissue damage region around the electrode tip gradually diminishes. In the array electrode implantation experiments, compared to a single electrode, the degree of tissue indentation is more severe due to the coupling effect between adjacent electrodes. As the array spacing increases, the coupling effect gradually diminishes. The experimental results indicate that appropriately increasing the velocity and array spacing of the electrodes can enhance the likelihood of successful implantation. The research findings of this article provide valuable guidance for the damage assessment and selection of implantation parameters during the process of electrode implantation into real brain tissue.

Characterization of the layer, direction and time-dependent mechanical behaviour of the human oesophagus and the effects of formalin preservation.

The mechanical characterization of the oesophagus is essential for applications such as medical device design, surgical simulations and tissue engineering, as well as for investigating the organ's pathophysiology. However, the material response of the oesophagus has not been established ex vivo in regard to the more complex aspects of its mechanical behaviour using fresh, human tissue: as of yet, in the literature, only the hyperelastic response of the intact wall has been studied. Therefore, in this study, the layer-dependent, anisotropic, visco-hyperelastic behaviour of the human oesophagus was investigated through various mechanical tests. For this, cyclic tests, with increasing stretch levels, were conducted on the layers of the human oesophagus in the longitudinal and circumferential directions and at two different strain rates. Additionally, stress-relaxation tests on the oesophageal layers were carried out in both directions. Overall, the results show discrete properties in each layer and direction, highlighting the importance of treating the oesophagus as a multi-layered composite material with direction-dependent behaviour. Previously, the authors conducted layer-dependent cyclic experimentation on formalin-embalmed human oesophagi. A comparison between the fresh and embalmed tissue response was carried out and revealed surprising similarities in terms of anisotropy, strain-rate dependency, stress-softening and hysteresis, with the main difference between the two preservation states being the magnitude of these properties. As formalin fixation is known to notably affect the formation of cross-links between the collagen of biological materials, the differences may reveal the influence of cross-links on the mechanical behaviour of soft tissues.

Risks of Powder Flow Obstruction in Hopper and Bin Discharge in Solid Dosage Form Manufacture should be Predicted Under The Active Stress State.

Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. In this study, we showed that the major principal stress (σ1) at the bin outlet is required for an accurate prediction of powder flow obstruction risks. We noted that powder is susceptible to flow obstruction when the unconfined yield strength exceeds the stress facilitating powder failure. We presented a complete model to calculate the stress conditions and subsequently predict flow obstruction risks in hopper/bin discharge based on this criterion. The method was experimentally verified by hopper/bin discharge experiments encompassing 10 powder blends and 2 equipment systems. Importantly, we showed that the active stress state assumption should be employed for the powder flow obstruction prediction because σ1 is high and powder is more susceptible to flow obstruction. Prediction under the passive stress state can lead to significant under-estimation of flow obstruction risks. Therefore, the hopper design protocol, which assumes the passive stress state in arching prediction, should not be indiscriminately used toward pharmaceutical powder flow applications.

The Mechanism of Deformation Compatibility of TA2/Q345 Laminated Metal in Dynamic Testing with Split-Hopkinson Pressure Bar.

The laminated metal materials are widely used in military, automobile and aerospace industries, but their dynamic response mechanical behavior needs to be further clarified, especially for materials with joint interface paralleling to the loading direction. The mechanical properties of TA2/Q345 (Titanium/Steel) laminated metal of this structure were studied by using the split Hopkinson pressure bar (SHPB). To shed light on the stress-state of a laminated metal with parallel structure, the relative non-uniformity of internal stress R(t) was analyzed. The mechanism of deformation compatibility of welding interface was discussed in detail. The current experiments demonstrate that in the strain rate range of 931-2250 s-1, the discrepancies of the internal stress in specimens are less than 5%, so the stress-state equilibrium hypothesis is satisfied during the effective loading time. Therefore, it is reasonable to believe that all stress-strain responses of the material are valid and reliable. Furthermore, the four deformation stages, i.e., the elastic stage, the plastic modulus compatible deformation stage, uniform plastic deformation stage and non-uniform plastic deformation stage, of the laminated metal with parallel structure were firstly proposed under the modulating action of the welding interface. The deformation stages are helpful for better utilization of laminated materials.

Changes in China's food security driven by nutrition security and resource constraints.

Food security and the utilization of natural resources in a sustainable manner are vital to the expansion of China's agricultural system. The relationship between environmental pressure and dietary structure has influenced the quantity and spatial distribution of China's food supply and demand, but it has not been evaluated. Our research centered on the security of China's food nutrition-resources-food (NRF) system, considering the inherent relationship between food security, nutritional health, and resource security. The following are the study's findings: (1) The Chinese population is rapidly changing from a diet focused on grains to a more diverse diet. Between 1990 and 2019, the dietary quality and nutritional status of Chinese individuals have vastly improved. In terms of nutrient levels, discrepancies between urban and rural resident persist, with urban residents consuming a diet that is closer to the ideal structure. However, the structure of rural residents' food consumption is diversifying, and the gap between urban and rural residents is gradually narrowing. (2) From 2000 to 2019, the pressure, status, and response indices of China's NRF system all show an upward trend, and the security of the NRF system has steadily grown. The magnitude of change in the response index exceeded that of the state index, which exceeded that of the pressure index. This indicates that the increase in the pressure and state indices of the NRF system was primarily attributable to the effectiveness of policy efforts.

Experimental and Numerical Investigation of the Mechanical Properties of a CFRP Tendon-Wedge Assembly Loaded under Transverse Compressive Loading.

Carbon-fiber-reinforced polymer (CFRP) tendons have become a viable alternative to steel cables in cable roof structures owing to their high tensile strength, low weight, and resistance to corrosion. However, the effective anchoring of CFRP tendons is a challenge because of their poor transverse mechanical properties. Therefore, the mechanical properties of CFRP tendons and a tendon-wedge assembly under transverse compression were investigated by simulating the force environment of the CFRP tendon inside an integrated-wedge anchorage. The deformation of and local damage to CFRP tendons under transverse compression were explored using load-strain curves and full-field strain measured using digital image correlation. The experimental and numerical results show that large-diameter CFRP tendons with a length in the range of 90-110 mm had better cross-sectional deformation resistance and more stable transverse mechanical properties. Longer CFRP tendons with larger diameters have lower contact compressive stress and local maximal shear stress under the same transverse compressive load. Based on the analysis of the experimental and numerical results, we propose design suggestions for tendon size selection and integrated-wedge design details, such as the manufacturing materials of the wedge, the radius through the gap of the wedge, and the radial difference of the groove, to improve the anchoring properties and efficiency of the integrated-wedge anchorage.

Studying the Plastic Deformation of Cu-Ti-C-B Composites in a Favorable Stress State.

Composites with a copper matrix attract the attention of researchers due to their ability to combine high ductility, heat conductivity, and electrical conductivity of the matrix with the high hardness and strength of the reinforcing phases. In this paper, we present the results of studying the effect of thermal deformation processing of a Сu-Ti-C-B composite produced by self-propagating high-temperature synthesis (SHS) on its ability to deform plastically without failure. The composite consists of a copper matrix and reinforced particles of titanium carbide TiC (sized up to 1.0 µm) and titanium diboride TiB2 (sized up to 3.0 µm). The composite hardness is 60 HRC. Under uniaxial compression, the composite starts to deform plastically at a temperature of 700 °C and a pressure of 100 MPa. Temperatures ranging between 765 and 800 °C and an initial pressure of 150 MPa prove to be the most effective condition for composite deformation. These conditions enabled a true strain of 0.36 to be obtained without composite failure. Under higher strain, surface cracks appeared on the specimen surface. The EBSD analysis shows that dynamic recrystallization prevails at a deformation temperature of at least 765 °C; therefore, the composite can plastically deform. To increase the deformability of the composite, it is proposed to perform deformation under conditions of a favorable stress state. Based on the results of numerical modeling by the finite element method, the critical diameter of the steel shell is determined, which is sufficient for deformation of the composite with the most uniform distribution of the stress coefficient k. Composite deformation in a steel shell under a pressure of 150 MPa, at 800 °C, is experimentally implemented until a true strain of 0.53 is reached.

A Methodology to Predict the Fatigue Life under Multi-Axial Loading of Carbon Fiber-Reinforced Polymer Composites Considering Anisotropic Mechanical Behavior.

Carbon fiber-reinforced polymers (CFRP) have been actively employed as lightweight materials; yet, evaluating the material's reliability under multi-axis stress states is still challenging owing to their anisotropic nature. This paper investigates the fatigue failures of short carbon-fiber reinforced polyamide-6 (PA6-CF) and polypropylene (PP-CF) by analyzing the anisotropic behavior induced by the fiber orientation. The static and fatigue experiment and numerical analysis results of a one-way coupled injection molding structure have been obtained to develop the fatigue life prediction methodology. The maximum deviation between the experimental and calculated tensile results is 3.16%, indicating the accuracy of the numerical analysis model. The obtained data were utilized to develop the semi-empirical model based on the energy function, consisting of stress, strain, and triaxiality terms. Fiber breakage and matrix cracking occurred simultaneously during the fatigue fracture of PA6-CF. The PP-CF fiber was pulled out after matrix cracking due to weak interfacial bonding between the matrix and fiber. The reliability of the proposed model has been confirmed with high correlation coefficients of 98.1% and 97.9% for PA6-CF and PP-CF, respectively. In addition, the prediction percentage errors of the verification set for each material were 38.6% and 14.5%, respectively. Although the results of the verification specimen collected directly from the cross-member were included, the percentage error of PA6-CF was still relatively low at 38.6%. In conclusion, the developed model can predict the fatigue life of CFRPs, considering anisotropy and multi-axial stress states.

Failure Behavior of Laser Metal Deposited Additive Manufacturing Ti-6Al-4V: Effects of Stress State and Initial Defects.

To investigate the mechanical property and failure behavior of laser metal deposited additive manufacturing Ti-6Al-4V (LMD Ti64) in a wide range of stress states and strain rates, different types of specimens were tested at strain rates of 0.001-5000/s. Numerical simulations were conducted to collect the local fracture strain at the critical position where the failure happened for all specimens. By comparing with Ti64 alloy manufactured by different techniques, the failure behavior of LMD Ti64 alloy shows a stronger sensitivity to Lode angle parameter and strain rate. The role of initial defects in failure was discussed. It is found that high laser power and overlap ratio can improve the failure behavior by reducing the number of initial defects. The initial defects on the fracture surface at much higher strain rates were observed, indicating that the initial crack rather than initial void acts as the crack growth point leading to the final fracture at higher strain rates. The scanning electron microscope observation of the fracture surface shows that the failure mechanism of LMD Ti64 alloy varies from different stress states and strain rates. The failure mechanism is characterized by the shear fracture at the negative stress triaxiality, whereas the void growth fracture plays a dominant role in the failure mechanism of LMD Ti64 alloy at a high stress triaxiality on the quasi-static loading condition.

Elastoplastic Analysis of Circular Steel Tube of CFT Stub Columns under Axial Compression.

Composite action between the components of the concrete-filled steel tube (CFT) is complex and it is difficult to accurately obtain the experimental relationship between the steel tube and the core concrete of CFT columns. The triaxially stressed core concrete has been studied by hydrostatic test in past research, while little research has been focused on the mechanical behavior of steel tube of CFT columns. It is difficult to obtain the experimental constitutive relationship of the steel tube of CFT columns to reflect the real-time influence of biaxial stress state and local buckling of steel plate on the steel tube. To clarify the mechanical behavior of the steel tube of CFT columns, this paper proposed an elastoplastic analytical method considering biaxial stress state and local buckling of steel tube to obtain the stress-strain curve of the steel tube. This method applied the Hook's law and the plasticity theory to interpret the information conveyed by the measured vertical and hoop strain histories of the steel tube. To verify its effectiveness, 11 circular concrete-filled steel tube stub columns were fabricated and tested under axial compression. Superposition results of the axial load-strain of steel tube and core concrete were compared against the experimental curves. The widely used Sakino-Sun model of the confined concrete was adopted to calculate the axial load-strain curve of the core concrete. Satisfactory agreements between the calculated and experimental results confirmed the rationality of the proposed method in tracing the constitutive relation of the biaxially stressed steel tube even after the occurrence of the local buckling. The obtained stress-strain relationship is critical for establishment of mathematical constitutive model and finite element model of steel tube.

Abnormal Twinning Behavior Induced by Local Stress in Magnesium.

This study investigated the twinning behavior with increasing compressive strain in rolled AZ31 alloy. With that purpose, a polycrystalline structure with an average grain size of 30 µm was utilized to perform the uniaxial compression tests. Microstructure evolution was traced by in situ electron backscattered diffraction (EBSD). Multiple primary twin variants and extension double twins were observed in the same grain. A comprehensive analysis of kernel average misorientation (KAM) and Schmid factor (SF) revealed that the nucleation of twins in one special grain is not only based on the SF criterion, but that it is also strongly influenced by surrounding grains. Moreover, the existing primary twins modified the inner and outer strain distribution close to the twin boundaries. With continued compression, the strain inside the primary twins stimulated the nucleation of double twins, while the strain in the matrixes facilitated twin growth. Therefore, the primary twin growth and the new nucleation of secondary twins could take place simultaneously in the same twinning system to meet the requirements of strain accommodation. Twinning behaviors are controlled by the combined effect of the Schmid factor, strain accommodation between surrounding grains, and variation in the local stress state. The local stress exceeded the critical resolved shear stress (CRSS), implying that twin nucleation is possible. Hence, the twinning process tends to be a response of the local stress rather than the applied stress.

Ozone Pollution, Oxidative Stress, Regulatory T Cells and Antioxidants.

Ozone pollution, is a serious health problem worldwide. Repeated exposure to low ozone doses causes a loss of regulation of the oxidation-reduction systems, and also induces a chronic state of oxidative stress. This fact is of special importance for the regulation of different systems including the immune system and the inflammatory response. In addition, the oxidation-reduction balance modulates the homeostasis of these and other complex systems such as metabolism, survival capacity, cell renewal, and brain repair, etc. Likewise, it has been widely demonstrated that in chronic degenerative diseases, an alteration in the oxide-reduction balance is present, and this alteration causes a chronic loss in the regulation of the immune response and the inflammatory process. This is because reactive oxygen species disrupt different signaling pathways. Such pathways are related to the role of regulatory T cells (Treg) in inflammation. This causes an increase in chronic deterioration in the degenerative disease over time. The objective of this review was to study the relationship between environmental ozone pollution, the chronic state of oxidative stress and its effect on Treg cells, which causes the loss of regulation in the inflammatory response as well as the role played by antioxidant systems in various pathologies.

Stress Component Decoupling Analysis Based on Large Numerical Aperture Objective Lens, an Impractical Approach.

Micro Raman spectroscopy is an effective method to quantitatively analyse the internal stress of semiconductor materials and structures. However, the decoupling analysis of the stress components for {100} monocrystalline silicon (c-Si) remains difficult. In the work outlined, physical and simulation experiments were combined to study the influence of the objective lens numerical aperture (NA) on the Raman stress characterization. The physical experiments and simulation experiments show that the spectral results obtained by using lenses with different NAs can accurately obtain the principal stress sum but cannot decouple the components of the in-plane stress. Even if the spectral resolution of the simulated experiment is ideal (The random errors of the polarization directions of less than ±1° and the systematic random errors of less than ±0.02 cm-1). The analysis based on the theoretical model demonstrates that the proportion of the principal stress sum in the Raman shift obtained in an actual experiment exceeded 98.7%, while the proportion of the principal stress difference part was almost negligible. This result made it difficult to identify the variable effects of different stress states from the experimental results. Further simulation experiments in this work verify that when the principal stress sum was identical, the differences in the Raman shifts caused by different stress states were much smaller than the resolution of the existing Raman microscope system, which was hardly possible to identify in the experimental results. It was proven that decoupling analysis of stress components using the large-NA objective lens lacked actual practicability.

Experimental Analysis of the Stress State of a Prestressed Cylindrical Shell with Various Structural Parameters.

The paper presents the results of experimental studies of the features of the operation of prestressed shells, taking into account the various structural parameters of the prestress. It is established that when the winding angle changes from perpendicular to the shell axis to 75° and 65°, the circumferential stresses decrease 1.4 times and 1.2 times, respectively, and the axial stresses increase five and three times, which are two and four times lower than the circumferential, from which it can be concluded that the reduction in the winding angle to the longitudinal the axis of the shell has a positive effect on the stress state of the structure. The study also found that with an increase in the diameter of the winding wire from 1 to 2 mm and a change in the winding angle, the same nature of the stress distribution is observed, but the values of the stress state parameter change, so the efficiency increases up to 25% due to an increase in the winding thickness, depending on the pitch, angle and thickness of the winding, which favorably affects the strength and the bearing capacity of the structure as a whole by increasing the value of the stress state parameter. Thus, the results of the analysis will allow us to use in more detail the possibility of controlling the stress-strain state of the prestressed shell by changing the design parameters, and the results obtained can be used in design or construction, as well as when increasing the strength characteristics of the structure, which allows us to create a high-tech design optimal for these operating conditions, which can positively complement the studies conducted earlier in this direction.

Effect Observation of Electro-Acupuncture Anesthesia Combined with General Anesthesia in Elderly Patients Undergoing Gastrointestinal Tumor Resection.

Objective: To investigate the anesthetic effect of electro-acupuncture (EA) anesthesia combined with general anesthesia in elderly patients undergoing gastrointestinal tumor resection, and to analyze the effects of EA anesthesia on inflammatory factors, stress state and T lymphocyte subsets in elderly patients. Methods: Total of 118 elderly patients who underwent gastrointestinal tumor resection in our hospital from June 2018 to March 2021 were selected and divided into the control group (59 cases) and the observation group (59 cases) according to the random number method. General anesthesia was adopted in the control group and EA anesthesia combined with general anesthesia was adopted in the observation group. The anesthesia effect, stress state, levels of inflammatory factors, T-lymphocyte subsets and adverse reactions were compared. Results: The VAS score, agitation score and respiratory normalization time in the observation group were lower than those in the control group (p < 0.05). After surgery, the levels of serum Cor, ET, NE and DA in the observation group were lower than those in the control group (p < 0.05). At 24 h after surgery, the levels of serum TNF-α, IL-6 and IL-1ß in the observation group were lower than those in the control group (p < 0.05). At 24 h after surgery, the levels of C D 3 + , C D 4 + , and C D 4 + / / C D 8 + in the two groups were lower than those before surgery, and the levels of C D 3 + , C D 4 + , and C D 4 + / / C D 8 + in the observation group were higher than those in the control group (p < 0.05). During the hospitalization, the total incidence rate of adverse reactions after anesthesia in the observation group was lower than that in the control group (p < 0.05). Conclusion: EA anesthesia combined with general anesthesia has good anesthesia effect when used for gastrointestinal tumor resection in the elderly. It can stabilize the internal environment of patients, alleviate postoperative stress response and inflammatory response, and regulate the body immune function. Moreover, it has high safety and can significantly reduce the occurrence of postoperative adverse reactions.

Influence of Psychological Nursing Procedure on Negative Emotion, Stress State, Quality of Life and Nursing Satisfaction in Patients with Lung Cancer Radical Operation.

Objective: To discuss the influence of psychological nursing procedure on negative emotion, stress state, quality of life and nursing satisfaction in patients with lung cancer radical operation. Methods: 106 patients with lung cancer who underwent radical resection in our hospital from September 2019 to September 2021 were selected. According to the intervention time, patients were divided into Group A and Group B, with 53 cases in each group. Group A received routine nursing, Group B used psychological nursing procedure on the basis of Group A. The negative emotions, stress state, quality of life and nursing satisfaction of patient were observed. Results: Self-rating anxiety scale and self-rating depression scale scores of Group B were lower than Group A (P < 0.05). The levels of norepinephrine, epinephrine and cortisol in Group B were lower than Group A (P < 0.05). Generic quality of life inventory-74 scores of Group B were higher than Group A (P < 0.05). The nursing satisfaction of Group B (88.68%) was higher than Group A (73.58%) (P < 0.05). Conclusion: Psychological nursing procedure is conducive to reducing the negative emotion, relieving stress reaction, improving the quality of life, increasing nursing satisfaction of patients with lung cancer radical operation.

Analytical Modeling of the Interaction of a Four Implant-Supported Overdenture with Bone Tissue.

Today, an interdisciplinary approach to solving the problems of implantology is key to the effective use of intraosseous dental implantations. The functional properties of restoration structures for the dentition depend significantly on the mechanical stresses that occur in the structural elements and bone tissues in response to mastication loads. An orthopedic design with a bar fixation system connected to implants may be considered to restore an edentulous mandible using an overdenture. In this study, the problem of the mechanics of a complete overdenture based on a bar and four implants was formulated. A mathematical model of the interaction between the orthopedic structure and jawbone was developed, and a methodology was established for the analytical study of the stress state of the implants and adjacent bone tissue under the action of a chewing load. The novelty of the proposed model is that it operates with the minimum possible set of input data and provides adequate estimates of the most significant output parameters that are necessary for practical application. The obtained analytical results are illustrated by two examples of calculating the equivalent stresses in implants and the peri-implant tissue for real overdenture designs. To carry out the final assessment of the strength of the implants and bone, the prosthesis was loaded with mastication loads of different localization. In particular, the possibilities of loading the prosthesis in the area of the sixth and seventh teeth were investigated. Recommendations on the configuration of the distal cantilever of the overdenture and the acceptable level and distribution of the mastication load are presented. It was determined that, from a mechanical point of view, the considered orthopedic systems are capable of providing long-term success if they are used in accordance with established restrictions and recommendations.