Fatigue Strength Research Articles

Long-Term Investigation of Nano-Silica Gel for Water Shut-Off in Fractured Reservoirs.

Silicate gels have long been utilized as water shut-off agents in petroleum fields to address excessive water production. In recent years, nano-silica gel has emerged as a promising alternative to traditional silicate gels, offering potentially improved plugging performance. However, the long-term effectiveness of these gels remains uncertain, posing challenges to sustained profitability. Therefore, a comprehensive study spanning 6 months was conducted on fractured and induced channel samples treated with nano-silica gel of 75/25 wt% (silica/activator) at 200 °F. A comparative analysis was performed with samples treated using polyacrylamide/polyethyleneimine PAM/PEI gel (9/1 wt%) to compare the performance of both systems. Throughout the aging period in formation water at 167 °F, endurance tests were conducted at regular intervals, complemented by computed tomography (CT) scans to monitor any potential degradation. The results revealed nano-silica gel's superior long-term performance in plugging fractures and channels compared to PAM/PEI gel. Even after 6 months, the nano-silica gel maintained a remarkable 100% plugging efficiency at 1000 psi, with a maximum leak-off rate of 0.088 cc/min in the mid-fractured sample and 0.027 in the induced channel sample. In comparison, PAM/PEI gel exhibited a reduction in efficiency to 99.15% in the fractured sample (5.5 cc/min maximum leak-off rate) and 99.99% in the induced channel sample (0.036 cc/min maximum leak-off rate). These findings highlight the potential of nano-silica gel as a more durable water shut-off agent for managing water production in fractures and channels.

Investigation of Predisposing Risk Factors in Adolescent Male Water Polo Players.

Shoulder injuries are prevalent in adolescent water polo (WP) players. Study aimed to determine whether preseason shoulder characteristics (range of motion [ROM], flexibility, and strength) and core endurance can identify athletes at risk of future shoulder injuries. Shoulder characteristics, including changes in ROM (internal rotation [IR], external rotation [ER], and total), strength (IR and ER), pectoralis minor flexibility, shoulder capsule flexibility, and core endurance, would be risk factors for shoulder reinjury in athletes with previous overuse injuries compared with noninjured athletes. Prospective cohort study. Level 3. At baseline, 53 male youth WP players (mean age, 16.6 ± 3.5 years) were assigned to Group 1 (with previous shoulder injuries [G1, n = 26]) and Group 2 (without previous shoulder injuries [G2, n = 27]). ROM, flexibility, strength, and core muscle endurance were assessed preseason. After a 12-month follow-up, players were again divided into those who developed new shoulder injuries (G3, n = 27) and those who remained healthy (G4, n = 26). Total of 26 players (49%) had previous shoulder injuries at baseline. At baseline, decreased pectoralis minor flexibility, IR, total ROM, and core endurance were found in players with a previous shoulder injury compared with players without a previous shoulder injury (P < 0.05). At baseline, a significant difference was present in proposed risk factors (shoulder and core endurance parameters) between players with and without a previous shoulder injury. Shoulder IR ROM and years of experience were significant predictors of shoulder injury. Early detection of modifiable proposed risk factors may help prevent reinjury in young athletes. Screening at an early age can help identify and address pre-existing injuries, support youth athletes' return to sport after a shoulder injury, prevent new injuries, and improve performance.

Quasi-static and fatigue performance of Ti-6Al-4V triply periodic minimal surface scaffolds manufactured via laser powder bed fusion for hard-tissue engineering

Additive manufacturing of Triply Periodic Minimum Surface scaffolds offers a promising solution for bone defect restoration and an alternative to traditional implants in hard tissue engineering. This study investigates the quasi-static and tension-compression cyclic properties of laser powder bed fusion-produced Ti6Al4V lattice-based architectures, specifically gyroid and diamond scaffold geometries. The scaffolds were designed to emulate the mechanical properties of bones, with pore sizes (650–1000 μm) suitable for tissue engineering, and porosities ranging from to 30–60 %. The quasi-static tensile properties of the stiffness and yield strength were characterized experimentally and validated numerically using the finite-element method. The results showed that the stiffness and tensile strength of the scaffolds were comparable to those of cortical bone, reducing the risk of scaffold failure. The influence of post-processing by heat treatment and hot isostatic pressing resulted in an increased fatigue limit and ductility compared with non-treated materials reported in the literature. Fractography analysis revealed that fatigue fracture initiation occurred at the outer surface of the skeleton structures, where the maximum tensile stress was concentrated. These findings support the assumption that the designed scaffolds accurately replicate the mechanical and fatigue characteristics of cortical bone, offering suitable alternatives for bone replacement and orthopedic implants.

Laser Cutting of Titanium Alloy Plates: A Review of Processing, Microstructure, and Mechanical Properties

The growing use of titanium alloys has led to the gradual replacement of traditional processing methods by laser cutting technology, making it the preferred method for processing titanium alloy plates due to its high efficiency, precision, and adaptability. In this review, the characteristics of laser cutting technology and its application in titanium alloy plate processing are summarized, outlining several aspects of the cutting process, microstructure, and mechanical properties of the material after cutting, along with simulation predictions. Previous research categorized laser-cutting input parameters into beam parameters and process parameters, with the commonly used parameters being the laser power, cutting speed, and gas pressure. Various parameter combinations can achieve different cutting qualities, and seven indices can be used to evaluate the cutting process, with the surface roughness and slit width serving as the most common indices. Different auxiliary gases have shown a significant impact on the laser cutting quality, with commonly used gases consisting of nitrogen, argon, and air. Argon-assisted cutting generally results in better surface quality. Due to the rapid temperature change, the titanium alloy microstructure will undergo a non-diffusive martensitic phase transformation during laser cutting, producing a heat-affected zone. Experimental studies and simulations of the mechanical properties have shown that the occurrence of a martensitic phase transformation increases the hardness and residual tensile stress of the material, which reduces the fatigue strength and static tensile properties. In addition, studies have found that the more streaks appear on the cut surface, the lower the fatigue strength is, with fatigue cracks arising from the stripes. Hence, the established analytical solution model and three-dimensional finite element model can effectively predict the temperature distribution and residual stress during the cutting process. This can provide a better understanding of the high residual stress characteristics of the cutting edge and the stripe formation mechanism, allowing researchers to better explore the mechanism of laser cutting.

Synchrotron X-ray radiation study of retained austenite stability and the effect on fatigue behavior of bainitic railway steels

The effect of retained austenite stability on the fatigue performance was studied in bainitic rail steel subjected to different heat treatments, including normalizing at 900 °C and normalizing at 900 °C combined with tempering at 320 °C. The normalized steel had yield strength of 851 MPa, tensile strength of 1131 MPa, uniform elongation 7.0 %, and total elongation 17.5 %. Tempering the steel at 320 °C resulted in similar strength and plasticity compared to the normalized condition. However, the fatigue performance of steel was improved significantly after tempering. The ultimate fatigue stress (endurance limit) after 1 × 107 cycles was 671 MPa, which was 38 MPa greater than the normalized steel. Microstructural analysis revealed similarities between normalized and tempered matrices at crystallographic interfaces and grain boundaries. Synchrotron X-ray radiation indicated that the initial retained austenite content was ∼15.5 % in both normalized and tempered conditions. However, at tensile stress of 800 MPa, the amount of retained austenite transformed in the normalized steel was ∼4 %, which was twice that of the tempered steel. The enhancement of retained austenite stability was an important aspect in improving the fatigue performance. The analysis of interphase spacing showed that the strain in the normalized matrix synchronized with the retained austenite, and the stress was concentrated in the retained austenite, which promoted transformation of retained austenite. The matrix of tempered steel was strained first, which prevented stress concentration in the retained austenite and rendered the retained austenite stable.

Influence of shot-peening on the self-heating behavior and fatigue properties of 300M steel

Shot peening is an established cold working process used to introduce residual compressive stresses on a surface and is extensively studied using conventional fatigue tests. However, it has not been widely studied using the self-heating method. Specifically, the heterogeneity of the dissipation field has not been estimated, with only an average approach being used. Previous investigations in the case of 300M steel demonstrated that the effect of shot peening on the high cycle fatigue properties can be either beneficial or detrimental. This study proposes to apply the self-heating method on polished 300M and to investigate the effect of mean stress and shot peening on the dissipation behavior. A modified self-heating model is proposed and calibrated for 300M steel. Combined with residual stress profiles, a method to compute and determine the shot peening effect on self-heating behavior through single point surface measurements is proposed. Application on 300M steel shows excellent results, the over-dissipation being mainly due to the sub-surface compressive residual stresses. The self-heating method has proven useful to quickly estimate fatigue properties of polished 300M steel. Based on the understanding of the self-heating curve of shot peened 300M steel, a quantification of shot-peening effect on fatigue limit is discussed.

Fatigue properties of a Ti–5Al–5Mo-5 V–3Cr alloy manufactured by electron beam powder bed fusion

AbstractAdditive manufacturing (AM) is a modern way of manufacturing structures, which tends to have fewer design limitations than those manufactured by conventional processes such as casting or forging. A combination of high-strength materials and small and complex structures opens up a wide range of potential applications, especially in the fields of medicine and aerospace. Titanium and its alloys show a very beneficial combination of density and mechanical properties. One of these alloys is the metastable β titanium alloy Ti– 5Al–5Mo–5 V–3Cr (Ti-5553), which is currently used mainly for large forged structures like landing gears of airplanes. In this study, for the first time the fatigue behavior of electron beam powder bed fused (PBF-EB) Ti-5553 was investigated with a focus on the defects created by the layer wise manufacturing. To understand the defect structure and its respective influence on the fatigue behavior, all specimens were scanned prior to fatigue testing using a state-of-the-art µ-focus CT. The specimens were subjected to two heat treatment procedures commonly used in technical applications, which were aiming for high strength (solution treated and aged—STA) as well as high ductility (beta annealed, slow cooled and aged—BASCA). Results indicate that the fatigue strength of PBF-EB manufactured Ti-5553 is significantly reduced compared to conventionally manufactured Ti-5553. The main reason for this are defects, which have varying critical effects depending on the heat treatment of the specimen and the defect size, shape, location and type.

Fatigue strength reliability assessment of turbofan blades subjected to intake disturbances based on the improved kriging model

This paper aims to develop an efficient and precise reliability analysis method to enhance the numerical prediction accuracy for complex structures. Kriging, an implicit surrogate model, used to address highly nonlinear and complex problems. In this study, genetic algorithms (GA) are utilized to optimize the parameters of the Kriging model, which is then integrated with a distributed collaborative strategy to introduce the Genetic Algorithm Optimized Distributed Collaborative Kriging Model (DCGAK). Using the CFM56-fan blade as a case study, the impact of intake disturbances at the engine inlet is evaluated to assess the fatigue strength reliability of the blade. Comparison with different mathematical models demonstrates that the prediction accuracy of DCGAK closely aligns with the Monte Carlo sampling results, suggesting promising prospects for its application in numerical prediction and reliability analysis. This approach enriches the current methods for structural reliability analysis of complex mechanical systems.

A review on progress trends of machining of Carbon Fiber Reinforced Plastics

In contemporary manufacturing industries, composite materials such as carbon fiber reinforced plastics (CFRPs) have become indispensable, finding extensive applications in aerospace, automotive, shipbuilding, high-tech sports equipment, and more. The exceptional chemical, physical, and mechanical properties of CFRPs, including high corrosion resistance, superior strength-to-weight ratio, high fatigue strength, and oxidation resistance, make them highly sought after. However, these very advantages pose significant challenges during machining due to the abrasive nature of composites, anisotropic mechanical properties, and poor thermal conductivity, which collectively exacerbate tool wear. This review paper addresses the critical need for innovative solutions to improve the machinability of CFRPs, a subject of paramount importance for advancing manufacturing efficiency and product quality. It comprehensively examines the latest research progress, current practices, and emerging trends in machining techniques such as turning, drilling (including reaming and countersinking), milling and grinding. The review delves into the influence of various cutting conditions, environments, and tool geometries. It also examines tool textures, materials, and coatings. Additionally, advanced machining methods, including vibration, thermal, and hybrid-assisted machining, are discussed. These factors impact key performance metrics such as cutting forces and torques, tool wear and life, chip morphology, surface roughness, and the quality of machined surfaces, including defect analysis. By synthesizing a vast array of literature for the first time, this paper highlights the most effective strategies to enhance machinability while extending tool life and improving surface finish. Notably, it underscores the innovative use of dry and flood lubrication, minimum quantity lubrication, cryogenic lubrication, and high-pressure cooling. Additionally, it emphasizes optimizing cutting tool geometry, employing diamond tools, and coating tools with TiN and TiAlN, alongside the application of heat treatment and hybrid machining methods, particularly those incorporating vibration machining techniques. This review not only identifies the current challenges but also proposes cutting-edge solutions, making it an essential resource for researchers and practitioners aiming to push the boundaries of CFRP machining technology.

Fatigue Resistance of the Sheets of Heat-Resistant Titanium Alloys

The results of a study of the resistance to fatigue fracture of sheets made of heat-resistant titanium alloys VT18U (Ti–6.5Al–4.3Zr–2.4Sn–0.8Nb–0.7Mo–0.1Si, wt.%), VT8 (Ti–6.4Al–3.4Mo–0.3Si, wt.%), and VT25U (Ti–6.51Al–3.76Zr–1.71Sn–3.94Mo–0.5W–0.13Si, wt.%) has been presented. Fatigue curves have been obtained in the initial state and in the oxidized one after isothermal annealing at a temperature of 560 °C for 1000 h in air. It has been established that after annealing, the fatigue resistance of all oxidized alloys in the low-cycle region decreases by an order of magnitude. The fatigue limit of the oxidized alloys VT18U and VT25U does not change and is about 320 MPa. The high-cycle fatigue limit of the VT8 alloy decreases from 300 MPa in the initial state to 230 MPa in the oxidized state. It has been established that after annealing, the phase composition of an oxide of 250 nm in thickness on the surface of the alloys is different and contains the phases of anatase and rutile for the VT18U and VT25U alloys and contains predominantly rutile for the VT8 alloys, which is why the fatigue limit of the oxidized alloys differs.

Facile fabrication of degradable, serrated polyethylene diacrylate microneedles using stereolithography

Microneedles have the potential for minimally invasive drug delivery. However, they are constrained by absence of rapid, scalable fabrication methods to produce intricate arrays and serrations for enhanced adhesion. 3D printing techniques like stereolithography (SLA) are fast, scalable modalities but SLAs require non-degradable and stiff resins. This work attempts to overcome this limitation by utilizing a poly (ethylene glycol diacrylate) (PEGDA, F3) resin and demonstrating its compatibility with a commercial SLA printer. FESEM images showed high printing efficiency of customized bioinks (F3) similar to commercial resins using SLA 3D printer. Mechanical endurance tests of whole MNA showed that MNs array printed from F3 resin (485 ± 5.73 N) required considerably less force than commercial F1 resin (880 ± 32.4 N). Penetration performance of F1 and F3 was found to be 10.8 ± 2.06 N and 0.705 ± 0.03 N. In-vitro degradation study in PBS showed that MNs fabricated from F3 resin exhibited degradation after 7 days, which was not observed with the commercial F1 resin provided by the manufacturer. The histology of porcine skin exhibited formation of triangular pores with pore length of 548 μm and efficient penetration into the deeper dermal layer. In conclusion, PEGDA can be used as for fabricating degradable, serrated solid MNs over commercial resin.

Comprehensive Analysis of Needle Bearing Failures in Fuel Transfer Pumps: Insights from Testing and Finite Element Analysis

&lt;div&gt;This study investigates the failure mechanisms of needle bearings within fuel transfer pump assemblies through a comprehensive approach combining endurance testing, detailed inspection, the Dykem blue method, proximity sensors, and finite element analysis (FEA). The findings reveal critical insights into the causes of failure, highlighting significant axial displacement, with a maximum of 0.37 mm measured by proximity sensors. The Dykem technique identified distinct wear patterns across various components, pinpointing areas of high stress and potential failure. Detailed bearing inspections uncovered trunnion damage and abrasive wear, corroborated by FEA, which quantified displacements of 0.144 mm in the x-direction, 0.030 mm in the y-direction, and 0.015 mm in the z-direction. The primary operational factors contributing to bearing failure were contamination and inadequate axial control. These insights are pivotal, as they align with and expand upon established literature on bearing failures, providing a deeper understanding of the interplay between mechanical wear and operational conditions. Despite the robustness of the methodology, challenges included ensuring the accuracy of axial displacement measurements and replicating real-world operational stresses in a controlled environment. The study proposes several recommendations to enhance axial support and optimize system design to mitigate the identified issues. The societal impact of this research is significant, offering potential improvements in machinery reliability, which can lead to enhanced industrial efficiency and safety standards. This work advances the current knowledge in the field and provides practical solutions for extending the lifespan and performance of critical mechanical components in fuel transfer systems.&lt;/div&gt;

Natural Seawater Impact on Crack Propagation and Fatigue Behavior of Welded Nickel Aluminum Bronze

ABSTRACTNickel aluminum bronze (NAB) is a complex alloy used extensively in the marine environment. Fatigue strength of NAB is reduced by welding and prior seawater corrosion. This study investigated the combined effect of corrosion and plasma welding on the fatigue behavior of NAB. Natural seawater corroded samples were used in tension‐tension cyclic loading tests to observe fatigue crack initiation, propagation, and failure. Fatigue cracks initiated from corrosion pits at the weld toe. Stress corrosion and fatigue cracks propagated along the path of β′ and κIII phases. A short crack growth model (SCGM) predicted fatigue strength using experimentally obtained material properties and corrosion pit dimensions. Model predictions were used to develop S‐N curves and were within 30% of experimental results. The SCGM produced accurate and reliable fatigue life results that could be applied by industry to aid in revalidation decision making and inspection scheduling.

Study on fatigue performance and topology optimization of cast steel bifurcation joint under alternating load

Abstract The numerical simulation analysis of a typical cast steel bifurcation joint under the alternating load was performed to comprehend its mechanical properties. The MSC Fatigue is used to explore and analyze the fatigue behavior of joints, and the control variable approach is used to examine the impact of various geometric parameters on fatigue life. Then, the load spectrum and fatigue life were invertedly calculated and transformed into maximum stress constraints by converting fatigue limitations into stress constraints. Finally, the optimal shape of cast steel bifurcation joint under fatigue limitations was studied using topology optimization methods, intending to solve the lightweight problem while still fulfilling fatigue design requirements. The research results show that the intersection of the main and branch pipes is the fatigue weakest part of the whole joint, and the geometric parameters significantly affect the joint's fatigue performance. The topology optimization shapes of cast steel bifurcated joints are different under vertical and horizontal loads, indicating that different load conditions significantly impact topology optimization shapes. The topology optimization method can reduce the self-weight while maintaining fatigue performance.&amp;#xD;

EFFECTS OF TEMPERATURE AND STRAIN AMPLITUDE ON LOW-CYCLE FATIGUE PROPERTIES OF NICKEL-BASED SINGLE-CRYSTAL SUPERALLOY DD419

High-temperature and low-cycle fatigue tests were conducted on a nickel-based single-crystal superalloy DD419 under total strain-controlled conditions at 760 °C and 980 °C. The fatigue properties of the alloy are discussed by analysing the fatigue test data. Fracture morphology and dislocation structure were observed using scanning electron microscopy and transmission electron microscopy. At the same strain amplitude, the results indicate that the plastic deformation of the alloy is larger at 980 °C compared to 760 °C. This leads to a lower fatigue strength and shorter fatigue life, along with more severe damage. The value of the strain amplitude affects the cyclic stress response behaviour of the alloy. Under low strain amplitudes, the cyclic stress response behaviour differs between 760 °C and 980 °C. The hysteresis loop exhibits similar shapes at 760 °C and 980 °C, with an increase in the area as the strain amplitude rises. The fatigue fracture analysis indicates that micropores on the surface are the primary fatigue sources at 760 °C, while oxides on the surface are the main fatigue source at 980 °C, leading to cracking due to multiple sources. Moreover, transmission electron microscopy reveals that the deformation mechanism involving dislocations at 760 °C primarily occurs through plane slip and wave slip, whereas at 980 °C, dislocations mainly move through cross slip and climb.

Sustainable Diamond Burnishing of Chromium–Nickel Austenitic Stainless Steels: Effects on Surface Integrity and Fatigue Limit

This study aims to evaluate the influence of lubrication and cooling conditions in the diamond burnishing (DB) process on the surface integrity and fatigue limit of chromium–nickel austenitic stainless steels (CNASSs) and, on this basis, identify a cost-effective and sustainable DB process. Evidence was presented that DB of CNASS performed without lubricating cooling liquid satisfies the requirements for a sustainable process: the three key sustainability dimensions (environmental, economic, and social) are satisfied, and the cost/quality ratio is favorable. DB was implemented with the same values of the main governing factors; however, four different lubrication and cooling conditions were applied: (1) flood lubrication (process F); (2) dry without cooling (process D); (3) dry with air cooling at a temperature of −19 °C (process A); and (4) dry with nitrogen cooling at a temperature of −31 °C (process N). Conditions A and N were realized via a device based on the principle of vortex tubes. All four DB processes provide mirror-finished surfaces with Ra roughness parameter values from 0.041 to 0.049 μm, zones with residual compressive stresses deeper than 0.5 mm, and increases in the specimens’ fatigue limit (as determined by the accelerated Locati’s method) compared to turning and polishing. Processes F and D produce the highest microhardness on the surface and at depth. The process D introduces maximum compressive residual axial and hoop stresses in the surface layer. The dry DB processes (D, A, and N) form a submicrocrystalline structure with high atomic density, which is most strongly developed under process D. When high fatigue strength is required, DB with air cooling should be chosen, as it provides a more favorable cost/quality ratio, whereas dry DB without cooling is the most suitable choice for applications that require increased wear resistance.

Advanced Analysis of Marine Structures—Edition II

One of the key issues in the design of modern ship and offshore structures is the accurate prediction of strength under various load conditions, especially impact, ultimate and fatigue strength [...]

Longitudinal comparison of the relationship of energy intake with body composition and physical performance in elite female basketball and volleyball players

Abstract Purpose To maximise sporting success, disciplines such as basketball and volleyball need to improve their methods of analysing the sporting performance and fitness of their athletes. Although energy intake quantities have been established at a theoretical level for women to perform at a sporting level, it has been found that these energy intake levels are not met or followed and that, despite this, the performance of female players is not diminished. Thus, the purpose of this research study was to describe and compare the anthropometric characteristics of these two disciplines and to identify the differences in actual and theoretical energy intake, as well as to observe physical performance in both disciplines. Methods Anthropometric data, continuous quantitative data, training time and characteristics, and energy intake data were collected. Performance tests included upper and lower body strength, speed, agility, and endurance tests. Dietary monitoring showed lower intakes of total energy, carbohydrate and protein than theoretically recommended. However, the athletes experienced overall improvements in performance and body composition. Results The mean total energy intake was 20.2 ± 4.3 kcal·kg−1·day−1. The minimum individual mean intake was 9.8 kcal·kg−1·day−1 and the maximum was 25.95 kcal·kg−1·day−1. Carbohydrates accounted for 54.3% ± 8.8% of the energy intake; 20.3% ± 6.5% from fats; 25.4% ± 5.7% from proteins. Conclusions Current data suggest that, although a cause-effect relationship between dietary intake and BC performance cannot be determined, elite athletes in these sports disciplines may experience beneficial outcomes despite having lower total energy, CHO, protein, and fat intakes than previously recommended in the literature.

Fatigue Life Assessment of Corroded AlSi10MgMn Specimens

This study investigates the influence of pre-corrosion damage on the fatigue behavior of AlSi10MgMn high-pressure die-cast specimens, using the statistical distribution of corrosion depths. The analysis is conducted on two different surface conditions: an unmachined rough surface (Ra=5.05μm) and a machined, polished surface (Ra=0.25μm). For the unmachined specimens, the corrosive damage manifests as homogeneously spread localized corrosion, whereas the polished specimens exhibit less uniform but deeper corrosion. The average corrosion depth of the polished specimens is found to be slightly higher (313 μm compared to 267 μm) with a broader depth distribution. Specimens are tested under a constant bending load amplitude in laboratory conditions at a stress ratio of R=0 until fracture. A fracture mechanics-based methodology is developed to assess the remaining fatigue life of corroded specimens, utilizing short and long crack fracture mechanical parameters derived from SENB specimens. This model incorporates a thickness reduction of the critical specimen cross-section based on the corrosion depth distribution and combines it with a small initial crack of the intrinsic defect size (aeff=14μm). Regardless of the surface condition, using the most frequent corrosion depth for thickness reduction provides a good estimate of the long-life fatigue strength, while using the 90th percentile depth allows for a conservative assessment.

Relationship between Body Mass Index, Dynamic Balance, and Core Muscle Endurance in Firefighter Candidates: A Cross-Sectional Study

This study aimed to examine the effects of Body Mass Index (BMI) on dynamic balance and core muscle endurance in firefighter candidates. In physically demanding professions, such as firefighting, understanding the impact of BMI on physical performance metrics is crucial for both occupational safety and effectiveness. The study was conducted with 89 firefighter candidates, with a gender distribution of 23.6% female (n=21, age 19.86±1.86 years, height 1.64±0.05 m, weight 59.47±7.26 kg) and 76.4% male (n=68, age 19.82±1.25 years, height 1.78±0.04 m, weight 74.36±12.09 kg). Within the scope of the research, the results of the BMI, balance, and core muscle endurance tests were evaluated. BMI was calculated based on measurements of participant height and weight. Dynamic balance performance was assessed using the Y-Balance Test, while core muscle endurance was measured using the plank test. The performances of the participants in both tests were recorded and subjected to statistical analysis. Pearson correlation analysis and multiple regression models were used to examine the relationships among BMI, dynamic balance, and core muscle endurance. The findings indicated that an increase in BMI has adverse effects on balance and core muscle endurance performance. Specifically, firefighter candidates with higher BMI values exhibited shorter plank durations (females: r=-0.63; p=0.002, males: r=-0.566; p