Element Stress Research Articles

Genome-wide identification and functional analysis of the cellulose synthase-like gene superfamily in common oat (Avena sativa L.)

Hemicelluloses constitute approximately one-third of the plant cell wall and can be used as a dietary fiber and food additive, and as raw materials for biofuels. Although genes involved in hemicelluloses synthesis have been investigated in some model plants, no comprehensive analysis has been conducted in common oat at present. In this study, we identified and systematically analyzed the cellulose synthase-like gene (Csl) family members in common oat and investigated them using various bioinformatics tools. The results showed that there are 76 members of the oat Csl gene family distributed on 17 chromosomes, and phylogenetic analysis indicated that the 76 Csl genes belong to the CslA, CslC, CslD, CslE, CslF, CslH, and CslJ subfamilies. A total of 14 classes of cis-acting elements were identified in the promoter regions, including hormone response, light response, cell development, and defense stress elements. The collinearity analysis identified 28 pairs of segmentally duplicated genes, most of which were found on chromosomes 2D and 6A. Expression pattern analysis showed that oat Csl genes display strong tissue-specific expression; of the 76 Csl genes, 33 were significantly up-regulated in stems and 30 were up-regulated in immature seeds. The expression of most members of the AsCsl gene family is repressed by abiotic stress, while the expression of some members is up-regulated by light. Immunoelectron microscopy shows that the product of AsCsl61, a member of CslF subfamily, mediates (1,3; 1,4)-β-D-glucan synthesis in transgenic Arabidopsis. These findings provide a fundamental understanding of the structural, functional, and evolutionary features of the oat Csl genes and may contribute to our general understanding of hemicellulose biosynthesis. Moreover, this information will be helpful in designing experiments for genetic manipulation of mixed-linkage glucan (MLG) synthesis with the goal of quality improvement in oat.

The superstructure behavior assessment of the railway bridge with truss element damage

The analysis of railway bridge accidents shows that at the present stage, the number of accidents and mechanical superstructures damage is associated with vehicle impacts. Bridge design standards recommend to check bridge structures for survivability, operational control standards do not cover such issues. To superstructure behavior assessment of a single-track railway bridge with truss element damage, a numerical study of changes in the stress-strain state of bridge superstructure was carried out within the framework of the dissertation research «Assessment of the operational reliability of metal spans with damage and methods of their monitoring». The object of the research is a typical superstructure with an estimated length of 66 m in the condition of complete or partial failure of various truss elements due to mechanical damage. As a result of the research, the nature of the redistribution of the stress-strain state of the superstructure was revealed. It is determined that the spatial redistribution of the stress-strain state occurs along the path of increasing stresses in the lattice elements of the parallel truss and longitudinal links. According to the control of allowable stresses and deflections, the survivability of the superstructure is maintained while 70 % of the single truss element elimination is reached. The elements for which mechanical damage is most dangerous have been identified.

Seasonal assessment of selected trace elements in grass carp (Ctenopharyngodon idella) blood and their effects on the biochemistry and oxidative stress markers

Environmental pollution by anthropogenic activity is still a highly relevant global problem. Aquatic animals are a specifically endangered group of organisms due to their continuous direct contact with the contaminated environment. Concentrations of selected trace elements in the grass carp (Ctenopharyngodon idella) (n = 36) blood serum/clot were monitored. Possible effects of the elements on selected biochemical and oxidative markers were evaluated. The concentrations of trace elements (Al, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Sr, Tl, and Zn) were analysed in the fish blood serum and blood clot by inductively coupled plasma optical emission spectrometry (ICP OES). A general scheme of decreasing concentrations of trace elements in the blood serum samples was: Zn ˃ Fe ˃ Sr ˃ Ba ˃ Ni ˃ Al ˃ Cu ˃ Be ˃ Co; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mn, Mo, Pb, Tl; and in the case of the blood clot, the scheme was as follows: Fe ˃ Zn ˃ Sr ˃ Al ˃ Ni ˃ Ba ˃ Cu ˃ Be ˃ Co ˃ Mn; < LOQ (below limit of quantification): Bi, Cd, Cr, Ga, Mo, Pb, Tl. Significant differences among the seasons were detected. The Spearman R correlation coefficients and linear or non-linear regression were used to evaluate direct relationships between trace elements and selected blood biomarkers. The correlation analysis between biochemical parameters (Na, K, P, Mg, AST, ALT, ALP, GGT, TAG, TP, urea, glucose) and trace elements (Al, Ba, Be, Cu, Fe, Ni, Sr, and Zn) concentrations confirmed statistically significant interactions in both seasons (summer and autumn). The regression analysis between oxidative stress markers (ROS, GPx, creatinine, uric acid, and bilirubin) and elements (Al, Ba, Co, Cu, Fe, Ni, and Sr) content confirmed statistically significant interactions. The results point to numerous connections between the observed elements and the physiological parameters of freshwater fish.

Comparative numerical study to simulate masonry with bed joint reinforced repointing

Bed joint reinforced repointing is a retrofitting technique for unreinforced masonry structures that is commonly applied in the Netherlands to repair settlement-induced damage. Using this technique, the bed joints of masonry walls are reinforced with steel rebars that are embedded in a high strength repair mortar. Due to the increase of induced seismic events in the northern part of the Netherlands, an experimental study was carried out at Delft University of Technology to investigate the performance of this retrofitting technique for combined settlement and seismic loading. This paper aims to simulate the experimental results, with a focus on the comparison of different finite element modelling approaches for studying both un-strengthened and strengthened full-scale tested walls. To that end, three different models are investigated – comprising both macro (continuum) and simplified and detailed micro (brick-to-brick) modelling approaches. The bricks and mortar joints are modelled as one homogenous continuum in the macro model, whereas in the two brick-to-brick models these structural components are modelled separately, with the detailed model including interface elements to simulate the brick–mortar bonds. Nonlinear pushover analyses are subsequently carried out using all three modelling approaches, for both monotonic and cyclic loading cases. Based on these analyses, the detailed brick-to-brick model was found unsuitable to simulate the strengthened wall because cracks in the model mainly occur in the form of opening of the brick–mortar bond interfaces, while smeared cracking in the plane stress elements of the mortar joints is very limited. Similarly, the continuum damage model was found to be inaccurate when pre-existing damage in the experiment needed to be taken into account. The continuum damage model also showed lower axial stresses in the rebars, compared with the simplified brick-to-brick model, as the former does not allow for the direct assignment of material properties for the high strength repair mortar in the strengthened joints.

The Menopausal Transition: Is the Hair Follicle "Going through Menopause"?

This article explores the link between menopause and changes in the hair follicle (HF) lifecycle, focusing on hormonal and metabolic dynamics. During menopause, hormonal fluctuations and aging can impact the HF, leading to phenomena such as thinning, loss of volume, and changes in hair texture. These changes are primarily attributed to a decrease in estrogen levels. However, not all women experience significant hair changes during menopause, and the extent of transformations can vary considerably from person to person, influenced by genetic factors, stress, diet, and other elements. Furthermore, menopause mirrors the aging process, affecting metabolism and blood flow to the HFs, influencing the availability of vital nutrients. The article also discusses the key role of energy metabolism in the HF lifecycle and the effect of hormones, particularly estrogens, on metabolic efficiency. The concept of a possible "menopause" clinically independent of menopause is introduced, related to changes in HF metabolism, emphasizing the importance of individual factors such as estrogen receptor responses, genetics, and last but not least, the microbiota in determining these dynamics.

A Poisson–Voronoi-based finite element stress analysis of resonating polysilicon micromachines

A Poisson–Voronoi-based finite element stress analysis of resonating polysilicon micromachines

Effect of spraying iron, zinc and using superabsorbent on grain yield and some biochemical properties of maize under drought stress

Nutrients such as iron and zinc play a vital role in controlling the negative effects of drought stress through the synthesis of enzymes, maintenance of cell membrane, and activation of antioxidant defense system. Due to these biochemical properties, an experiment was conducted to evaluate effect of spraying iron, zinc and using superabsorbent on grain yield and some of biochemical properties of maize under drought stress in a randomized complete block design in Shooshtar city during the years 2017–2018. The experimental treatments included three levels of drought stress (Irrigation after 30%, 40% and 50% evaporation). Sub-plots consisted of superabsorbent polymer at two levels (control and 200 kg/ha) and combination of iron and zinc (control, iron, zinc, and iron-zinc). The results showed that drought stress affected chlorophyll, proline, iron grain concentration, nitrogen percent, grain protein and grain yield. Drought stress caused a significant reduction in yield. The percentage of grain protein was significantly increased in irrigation treatment at 50% of farming capacity. The highest grain yield and chlorophyll index was observed in 30% irrigation treatment. Spraying iron and zinc significantly increased the grain yield, chlorophyll index, iron, and zinc concentrations. Furthermore, drought stress and superabsorbent interacted significantly on grain yield. The interaction among drought stress and superabsorbent elements had significant effects on zinc and iron concentration. The present study suggests that using 200 kg/ha superabsorbent polymer and spraying iron and zinc under the 40% post-discharge irrigation may improve grain yield and biochemical features of maize.

A corotational isogeometric assumed natural strain shell element in updated lagrangian formulation for general geometric nonlinear analysis of thin-walled structures

A new general geometric nonlinear curved quadrilateral shell element, which can handle large displacements and large rotations, is presented in this paper. It is formulated based on the incremental virtual work equation in updated Lagrangian formulation for general large displacement analysis. The kinematics of shell element is described using non-uniform B-spline patch, which results in the element displacement field with higher order continuity and the element performance more resistive to shear locking and membrane locking. In order to perfectly avoid such membrane locking and shear locking behaviors, the assumed in-plane membrane strain field and the assumed transverse shear strain field for the incremental covariant Green-Lagrange strain are constructed as linear combinations of non-uniform B-spline basis functions with degrees lower than those adopted by the original displacement field interpolation. In addition, based on Euler parameters, the corotational procedure available for high order isogeometric shell element is developed to extract the strain-producing deformational displacements and rotations and to update the element stresses and realistic internal force vectors. The accuracy and robustness of proposed shell element are demonstrated through the solutions of various benchmark problems.

Evaluation of Structural Stresses of Mountain-Embedded Railway Systems

Mountain railways are constructed on terrains with steep gradients and operate under unique conditions as they climb slopes at low speeds using rack rails. Recently, mountain railway systems in the form of embedded rail systems (ERSs) have been developed to minimize environmental damage caused by the construction of new roads. However, the use of ERS in mountain railway tracks is still limited, and research on their safety and behavior is lacking. Therefore, this study was conducted to evaluate the safety profile and behavioral responses of mountain-ERS under a steep gradient condition of 180‰. The effects of using high-strength concrete materials for precast concrete panels were investigated in this study, and the safety profile and behavioral response of mountain-ERS based on changes in the gradient and after adjusting the thickness of the subgrade of mountain-ERS was assessed. Under load conditions, the maximum tensile stress in the concrete elements did not exceed the tensile strength of the concrete. In the structural behavioral analysis, the patterns of stress variation were analyzed by applying stress to the concrete elements. The safety assessment and behavioral analysis results obtained in this study are considered valuable foundational research data for analytical studies on mountain-ERSs.

Estimated microplastic stress and potential affiliated toxic elements on phytoplankton in a floodplain-lake system.

Hazards associated with microplastics (MPs) and the pollutants they absorb in freshwater lake ecosystems have become a hot research topic in academia. In this study, in order to investigate potential affiliated MP hazards, lake MP samples were collected from a typical subtropical freshwater lake system in China (Poyang Lake) during the dry season (here, you should show the specific months) to explore their potential toxic element (PTE) response (i.e., exposure to Cu, Pb, and Zn) respective to the ecological environment and resident phytoplankton. Results show that average MP abundance in surface water can reach up to 1800 items m-3, which higher in the Nanjishan Wetland National Nature Reserve (NWNNR) (1175 items m-3). Polyester (i.e., purified terephthalic acid [PTA]) and polyethylene (PE) were the main polymer types found in surface water, fiber was the main MP shape, and most of the MP particle sizes are greater than 100 μm. Moreover, phytoplankton biomass was significantly higher in the NWNNR compared to Poyang Lake's retention basin and water channel. It indicated that MP pollutant status of Poyang Lake is mild; however, the ecological risks that MPs pose should not be ignored. The significant positive correlation between MPs and PTEs indicated that PTE absorption and desorption by MPs may cause potential ecological stress. Although we anticipate no direct link between ecotoxicity and phytoplankton, MPs may have indirect effects on phytoplankton through their regulatory effects on PTE levels in water.

An experimental and statistical study on the characteristics of non-metallic inclusions that serve as hydrogen-induced crack nucleation sites in pipeline steel

This study consists of a statistical study to identify spatial distribution parameters of non-metallic inclusions (NMIs) at hydrogen-induced cracking (HIC) nucleation sites in both low-strength and high-strength steel pipes. The electrochemical cathodic charging method was used to induce HIC in pipeline steel plates, and the nucleation of the HIC was monitored using straight beam ultrasonic testing. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to evaluate the shape, size, area fraction, and separation distance of NMIs. The hydrogen microprint technique (HMT), electron backscattered diffraction (EBSD) analysis, and finite element (FE) stress analysis were performed to characterize HIC nucleation sites. The findings showed that cubical and spinal NMIs, characterized by strong hydrogen trapping capacity due to high misfit strain and von Mises stress, are favored sites for HIC nucleation. The main finding of this study is that the shape and sharpness of NMIs are the factors that determine when NMIs will be a HIC nucleation site, rather than size, as generally accepted.

Managing Stress &amp; Mental Well-being in the NHS Staff

This article focuses on the workplace stress and mental well-being element and considers views on who is responsible for managing stress at work and promoting mental well-being.

Finite element stress analysis of dental cement application on endocrown and onlay restoration.

The aim of the study was to evaluate the influence of resin cement material types on tooth with endocrown and onlay restorations. The first molar was scanned using Micro-CT and underwent a modelling process to obtain the 3D model for computational simulation. Eight models were simulated in the current study with two loading conditions (720N vertical load and 200N oblique load), two types of restoration (onlay and endocrown restorations), and two resin cement variants (dual-cure resin cement and light-cure resin cement). The tooth with onlay restoration showed a significant stress reduction (up to 70%) when using light-cure resin cement compared to dual-cure resin cement. In contrast, types of cement did not affect stress distribution in the tooth with endocrown restoration. The current study found that dual-cure resin cement was preferable in Endocrown and Onlay restorations, due to dual-cure resin cement provided better bond strength compared to light-cure resin cement.

Three-dimensional finite element stress analysis of surface-mounted inlays in repairing pulp-penetrating non-carious cervical lesion of maxillary first premolar.

This study aimed to explore the stress distribution of surface-mounted inlays with two ceramic materials and different strategies for fiber post-restoration on pulp-penetrating non-carious cervical lesion in a maxillary first premolar to provide minimally invasive and reasonable restorative methods. The cone beam computed tomography data of the standard right upper first premolar were selected. Healthy control (HC) and defective control (DC) finite element models were established. Then, eight experimental models were established according to two different ceramic materials (IPS e.max CAD [LD] and Lava Ultimate [LU]) and different locations of fiber post (without fiber post [NP], fiber post in buccal root canal [B], fiber post in palatal root canal [P], fiber post in both root canals [BP]), namely, LDNP, LDB, LDP, LDBP, LUNP, LUB, LUP, and LUBP. Axial load F1 and lateral load F2 were applied. Maximum principal stress and displacement of the buccal tip were investigated using finite element analysis software. Then, the percentage change of the following indicators in each experimental group was analyzed: stress of defective tip with group DC, stress of enamel and dentine, and displacement of buccal tips with group HC. It was considered similar when the percentage change was less than 5%. LD and LU groups could effectively reduce the stress of the defective tip, but the decreasing amplitude in the former was greater than that of the latter. For the stress of surface-mounted inlays and resin adhesive layer, LD groups were higher than LU groups, and no significant difference in stress peak was found among different experimental groups in the same material. In addition, fiber posts in double root canals could significantly reduce buccal tip displacement. For pulp-penetrating non-carious cervical lesions, the restorative strategy of surface-mounted inlays could be applied. Compared with Lava Ultimate, IPS e.max CAD could better protect the defective tip tooth. Furthermore, fiber posts in double root canals could decrease overall deformation and increase the retention of surface-mounted inlays.

Effect Of Hardening On Germination And Seedling Characters Of Maize (Zea Mays L)

The ideal temperature is necessary for the maize crop to provide the highest harvest yield. Environmental stress elements such as abiotic and biotic stress factors are expected to intensify and become more widespread as a result of climate change. Drought, temperature, and salinity are the key factors affecting maize output globally. Various management practices may help in contributing tolerance to the plants against adverse environmental impact, and seed hardening is one among them. The experiment was conducted in the laboratory of Seed science and Technology, Department of Agriculture, Kalasalingam School of Agriculture and Horticulture, Krishnankoil, Tamil Nadu to study the effect of various hardening treatments in maize seeds. Maize seeds were hardened with the following chemicals at varying concentrations for 12 hours viz., T0 – Control, T1 – Distilled water, T2 – Boric acid (0.5%), T3 – Boric acid (1.0%), T4 – Boric acid (1.5%), T5 – KNO3 (0.5%), T6 – KNO3 (1.0%), T7 – KNO3 (1.5%), T8 – KH2PO4 (0.5%), T9 – KH2PO4 (1.0%) and T10 – KH2PO4 (1.5%). Significant differences were found between control and hardening treatments. Maximum germination percentage, shoot, and root length, seedling length, fresh and dry weight of the seedling vigor index were observed for the seeds treated with 1.5% KNO3. This experiment also showed the positive influence of KH2PO4 (1.5%) in various seedling characters followed by 1.5% KNO3. This study might help to improve the seedling character with the help of seed-hardening treatments to withstand adverse abiotic stress situations

Monitoring the technical state of load-bearing structures of the Luzhniki Stadium during reconstruction

Introduction. The paper presents the methods of reinforcing brick-and-stone structures, as well as monitoring of their strain capacity during the reconstruction of the Grand Sports Arena of Luzhniki Olympic Complex. The authors paid special attention to the methods for ensuring the preservation of front wall made of ceramic hollow stones.Aim. To ensure the reliability and stability of the wall of the Grand Sports Arena during the stadium reconstruction, in particular during the dismantling of the framework and stands.Materials and methods. The authors calculated the strain capacity (vertical deviation) of the framework of the stands at its dismantling stage and the wall stability, taking into account the framework fastening with rolled steel braces. The wall section taken for calculation at the first stage of dismantling stands consisted of several spans of 6 meters each. An extreme wind action was considered as the main stress factor that has the most severe impact on the front wall strain.Results. The calculations showed that the wind load on the system “front wall + 1 span of the stand framework” increases tensile and compressive stresses in the load-bearing elements by no more than 5–7% compared to the system “front wall + 2 spans of the stand framework”. Based on the calculations performed, only one span of the stand framework adjacent to the front wall was decided to retain. Monitoring of the structures strain confirmed the reliability and efficiency of the adopted solutions to strengthen the retained structures.Conclusion. Due to R&amp;D support for the design and reconstruction of the Luzhniki Grand Sports Arena, complex issues arising in the process of reconstruction were efficiently solved. The principles of the Arena reconstruction can be applied to other similar facilities.

Explicit Method in the Seismic Assessment of Unreinforced Masonry Buildings through Plane Stress Elements

The complex nonlinear behaviour of unreinforced masonry (URM), along with the interaction between structural elements, still represents a challenge for the seismic assessment of existing URM buildings. A large variety of mathematical tools have been developed in the last decades to address the issue. The numerical work herein presented attempts to provide some insights into the use of FEM models to obtain reliable results from nonlinear dynamic analyses conducted with explicit methods. Through plane stress elements, two in-plane mechanisms were studied to identify optimal parameters for unreinforced masonry elements subjected to dynamic actions. The results were then compared with outcomes generated by an implicit solver. Subsequently, these parameters were used in nonlinear dynamic analyses on a building section for the seismic assessment in both unreinforced and reinforced conditions. The element type, hourglass control, damping, and bulk viscosity influence the dynamic response, mainly when the nonlinearities become larger. The hourglass control techniques employ a scaling factor to suppress the occurrence of spurious modes. Values ranging from 0.01 to 0.03 have shown effective results. When the stiffness-damping parameter for Rayleigh damping is of a similar order of magnitude or lower than the time increment without damping, the time increment remained in feasible ranges for performing analysis. Additionally, the bulk viscosity can stabilise the response without causing substantial alterations to the time increment if the values are under 1.00.

Prosedur Pemeriksaan MRI Lumbal pada Kasus Efusi Pleura Suspek Tuberkulosis

Background: Clinical vertebral tuberculosis (TB) occurs outside the lungs affecting the spine. It generally infects the spine in the lower thoracic and upper lumbar spine. MRI examination is performed on clinical vertebral TB patients to determine the degree of stress and changes in bone elements in the early stages of the disease. This study aims to analyze the lumbar MRI examination procedure in cases of suspected TB pleural effusion. Methods: This research was qualitative with a case study approach. Data collection was carried out at the Radiology Unit of Premier Bintaro Hospital with the methods of observation, interviews, and documentation. Data processing and analysis were carried out descriptively. Results: Lumbar MRI examination with suspected TB pleural effusion at the Radiology Unit of Premier Bintaro Hospital was not specially prepared, the patient was examined first through the patient checklist to avoid metal materials entering the examination room. Examination using the Non-Contrast Lumbar MRI protocol included of sagittal and coronal T2, sagittal T1, sagittal Short Tau Inverse Recovery (STIR), Myelography, Axial T2, and Axial T1. The results of the examination provided sufficient diagnostic information to indicate a vertebral TB lesion. Conclusions: The procedure for examining lumbar MRI in TB cases with suspected pleural effusion at the Radiology Unit of Premier Bintaro Hospital did not require special preparation, the examination protocol used was to provide TB clinical diagnostic information, the addition of Gadolinium contrast media could be an alternative choice.

Mineral elements and adiposity-related consequences in adolescents with intellectual disabilities

BackgroundPatients with intellectual disabilities are shown to have a limited capacity for cooperation, communication,and other biological consequences, which significantly require a specialized interest in healthcare professionals worldwide.AimIn this respect, the present study was designed to evaluate the levels mineral elements, and their correlation with oxidative stress markers and adiposity markers; leptin (L), adiponectin (A), and L/A ratio in adolescents with intellectual disabilities.MethodsA total of 350 schoolchildren aged (12–18 years) were randomly invited to participate in this prospective, observational study. Only 300 participants agreed to participate in this study. According to Intelligence quotients scores (IQ) measured by WISC-III, the participants were classified into two groups; the healthy control group (no = 180; IQ = 90–114); and the moderate intellectual disability (MID) group (no = 120; IQ = 35–49). Adiposity markers; body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), physical activity scores, adipokines biomarkers; leptin, adiponectin, L/A ratio, oxidative stress, and plasma mineral elements were evaluated by prevalidated questionnaires, inductively coupled plasma-mass spectrometry (ICP-MS), colorimetric, and immunoassay techniques.ResultsIntellectual disability of moderate type was reported in 40% of the studied populations most of them are men aged 12–18 years (66.6% for men vs. 33.3 for females). Obesity was shown to be associated with the degree of intellectual disability of the students. There was a significant (P = 0.001) increase in the BMI, WHR, and WHtR scores as obesity markers with poor physical activity (P = 0.01) in students with poor disability compared to healthy controls (HC). The levels of leptin (P = 0.001), adiponectin (P = 0.01), and L/A ratio (P = 0.01) as adiposity biomarkers were significantly increased in students with MID compared to healthy controls. Also, oxidative stress measured by malondialdehyde (MDA) (P = 0.01) and total antioxidant capacity (TAC) (P = 0.01) were significantly increased in students with MID compared to healthy control subjects. In addition, mineral elements were shown to be linked with intellectual disability. The data showed that the levels of Fe, Mn, Zn, Hg, Pb, Ca, Cr, Mg, and Ni significantly (P = 0.001) increased, and the levels of Al, Na, K, Cu, and Zn/Cu ratio significantly (P = 0.001) decreased in subjects with MID compared to healthy controls. Correlation analysis concluded that changes in mineral elements significantly correlated with adiposity markers, oxidative stress, and the scores of intellectual disability (WISC III-IQ score).ConclusionThe intellectual disability of moderate type (MID) was associated with abnormal changes in the levels of essential mineral elements and adipokines and increased levels of cellular oxidative stress. Thus, evaluating plasma mineral elements and adipokines levels could be a potential diagnostic parameter for diagnosing MID.

Failure characteristics and service life prediction of polycrystalline diamond compact (PDC) cutter under cyclic impact loading

This paper aims to investigate the cyclic impact damage characteristics and service life of PDC cutters under varying impact loadings, angles, and depths. Additionally, a life prediction model is established to predict the fatigue life of flat cutters, axe cutters, and triangular cutters. A customized impact test device was utilized to conduct the cyclic impact test, and a finite element model was calibrated based on the experiment result of flat PDC cutter. Then, the model was used to analyze the stress distribution in the axe and triangular cutters, respectively. By combining the experimental and numerical results, the S–N (Stress-Number of times) curve representing the fatigue failure of the PDC cutter substrate was established. Moreover, the fatigue life of different PDC cutters under impact loading was predicted by integrating the S–N curve with the results of finite element stress analysis. The findings indicate that triangular cutters exhibited the longest fatigue life, with a 30.36% increase compared to flat cutters, under an impact angle of 15°, an impact depth of 4 mm, and an impact loading of 7616N. Similarly, the fatigue life of axe cutters was 7.59% higher than that of flat cutters. These findings suggest that non-flat cutters have greater impact resistance and are more suitable for heterogeneous strata characterized by significant impact stress variations.