Fatigue Threshold Research Articles

Different Smoothing Window Lengths can Estimate the Neuromuscular Fatigue Threshold at The same Intensity of the Lactate Threshold During the Leg Press Exercise

Background: This study aimed to compare different smoothing window lengths used to compute the RMS and their impact on RMS slope during leg press exercise and to compare the RMS slope behavior with lactate threshold. Methods: Twelve subjects performed an incremental test on a leg press machine where blood lactate concentration was measured at each stage. The RMS of vastus medialis (VM), vastus lateralis (VL) and rectus femuralis (RF) were computed for 200, 1500 and 3000ms windows length periods, and the RMS linear slope was used to interpret the results in the amplitude domain. The EMG fatigue threshold (EMGth) was determined for the quadriceps muscle during the three smoothing window lengths. Results: There was no significant difference (p> 0.05) in RMS slope between the three different RMS window length analyses for VM and VL muscles. The RMS slope was significantly higher (p ≤ 0.05) for the window length period of 1500 and 3000ms compared to 200ms in some intensities of exercise. The ICCs between the RMS slopes were 0.94 for RF and 0.95 for VL and VM. There was no significant difference (p> 0.05) between the EMGth at different window length periods and the lactate threshold (28.0 ± 3.7% of 1RM). Conclusion: Different smoothing window lengths to computed RMS could be used during resistance exercise without differences in RMS slope. The smoothing window lengths don´t influence EMGth intensity and are related to the lactate threshold.

The cyclic R-curve method for predicting fatigue crack growth threshold based on modified strip-yield model of plasticity-induced crack closure under fully reversed loading

A strip-yield model modified to leave plastically deformed stretch in the wake of the advancing crack tip is applied to simulate the buildup of plasticity-induced crack closure with crack extension from precracks with various lengths under fully reversed loading. Two types of precracks are examined: open precracks which remain open even under cyclic compression, and closed precracks which may close under compression. The effects of precrack type and length on fatigue thresholds were systematically examined. Because of a sharp increase of crack opening stress with crack extension, the effective stress intensity range ΔKeff drops initially and then turns to increase. Assuming a constant threshold value of ΔKeff for steels, new master curve equations are proposed for the cyclic R-curve. The effect of the precrack type on fatigue thresholds is successfully derived for different precrack lengths.

Chemically identical gels I – under-crosslinked networks

Do materials prepared from identical compositions of constituting ingredients always exhibit similar mechanical properties? The answer is negative for most structural materials, as has been demonstrated by extensive studies on various factors such as the effects of processing and microstructures. However, the same question has seldom been addressed in the case of polymeric gels. In this work, by using a simple chemically crosslinked hydrogel as a model system, the mechanical properties, including elastic stiffness, fracture toughness, and fatigue threshold, of gels with identical chemical compositions are systematically investigated. The distinct material properties are then rationalized and quantitatively correlated to synthesis conditions and manufacture processes through scaling laws derived from basic physics. Different scaling laws are identified between samples prepared from swelling and deswelling. Extreme mechanical properties, such as the remarkable fracture energy of hydrogels prepared by deswelling from highly swollen samples, are observed and attributed to the structural characteristics of the polymer network, and further correlated to the synthesis processes. This study provides insights into the synthesis-property correlations of polymeric gels, which may have profound influences on the design of new polymeric materials and their applications in various fields.

Solvent-Exchange-Assisted Wet Annealing: A New Strategy for Superstrong, Tough, Stretchable, and Anti-Fatigue Hydrogels.

Hydrogels are widely used in tissue engineering, soft robots, wearable electronics, etc. However, it remains a great challenge to develop hydrogels possessing simultaneously high strength, large stretchability, great fracture energy, and good fatigue threshold to suit different applications. Herein, a novel solvent-exchange-assisted wet-annealing strategy is proposed to prepare high performance poly(vinyl alcohol) hydrogels by extensively tuning the macromolecular chain movement and optimizing the polymer network. The reinforcing and toughening mechanisms are found to be "macromolecule crystallization and entanglement". These hydrogels have large tensile strengths up to 11.19 ± 0.27MPa and extremely high fracture strains of 1879 ± 10%. In addition, the fracture energy and fatigue threshold can reach as high as 25.39 ± 6.64kJ m-2 and ≈1233 J m-2 , respectively. These superb mechanical properties compare favorably to those of other tough hydrogels, organogels, and even natural tendons and synthetic rubbers. This work provides a new and effective method to fabricate superstrong, tough, stretchable, and anti-fatigue hydrogels with potential applications in artificial tendons and ligaments.

Microstructural influences on fatigue threshold behavior and fracture toughness of an additively manufactured γ-titanium aluminide

The fracture and fatigue behavior of an additively manufactured γ-TiAl alloy (BMBF3) produced by selective electron beam melting and further subjected to two different heat treatment conditions was investigated. As one of the heat-treatments led to a pronounced layer structure, the experiments were also performed with different specimen orientations to account for possible anisotropy effects. In order to characterize the frequently found peculiarities of the local fracture process in this material class, such as shear ligament bridging, static and cyclic R-curves were recorded. In addition, also fatigue crack growth curves were measured. The results were critically compared with the properties of a selected heat treatment condition of an established TNM alloy manufactured by a conventional processing route. The investigations show that large α2/γ-colonies lead to high fracture toughness, but have almost no positive effect on the long-crack fatigue threshold. On the other hand, duplex microstructures with small α2/γ-colonies and thick lamellae favor high long-crack thresholds, but low fracture toughness. Microstructures with high fractions of globular γ-phase exhibited both, low fracture toughness and low long-crack fatigue threshold values. In comparison to the established TNM reference alloy, the additively manufactured counterparts can compete especially when the evolving anisotropy of the properties is taken into account for component design.

Anti-fatigue ionic gels for long-term multimodal respiratory abnormality monitoring

Wearable electronics integrated with stretchable sensors are considered a promising and non-invasive strategy to monitor respiratory status for health assessment. However, long-term and stable monitoring of respiratory abnormality is still a grand challenge. Here, we report a facile one-step thermal stretching strategy to fabricate an anti-fatigue ionic gel (AIG) sensor with high fatigue threshold (Γ0 = 1130 J m–2), high stability (> 20,000 cycles), high linear sensitivity, and recyclability. A multimodal wearable respiratory monitoring system (WRMS) developed with AIG sensors can continuously measure respiratory abnormality (single-sensor mode) and compliance (multi-sensor mode) by monitoring the movement of the ribcage and abdomen in a long-term manner. For single-sensor mode, the respiratory frequency (Fr), respiratory energy (Er), and inspire/expire time (I/E ratio) can be extracted to evaluate the respiratory status during sitting, sporting, and sleeping. Further, the multi-sensors mode is developed to evaluate patient-ventilator asynchrony through validated clinical criteria by monitoring the incongruous movement of the chest and abdomen, which shows great potential for both daily home care and clinical applications.

Effect of compression precracking on the near threshold fatigue crack propagation in an AISI 316L stainless steel

This work addresses an alternative test procedure based on fatigue precracking under compression to mitigate the potential effects of crack closure on near-threshold fatigue data and, thus, to obtain more consistent and reliable ΔKth-values. The method relies on performing a compression precracking, in which both maximum and minimum loads are compressive, thereby resulting in a tensile residual stress field at the crack tip. Fatigue crack growth (FCG) tests conducted on an AISI 316L stainless steel provide the experimental data upon which the near-threshold fatigue crack growth rate data for different test techniques can be determined. The experimental program includes FCG tests conducted on conventional C(T) specimens with crack size to specimen width ratio a/W=0.2, single edge notched SE(B) specimens under three-point bending with a/W=0.2 and two different span sizes, S, characterized by S/W=4 and 8. Overall, the present investigation shows that combining the compression precracking technique with the utilization of non-standard bend specimens having increased span improves evaluation of the near-threshold fatigue crack growth rate data for the tested AISI 316L steel, thereby providing more accurate ΔKth-values.

Tough and fatigue-resistant polymer networks by crack tip softening

Soft materials fail by crack propagation under external loads. While fracture toughness of a soft material can be enhanced by orders of magnitude, its fatigue threshold remains insusceptible. In this work, we demonstrate a crack tip softening (CTS) concept to simultaneously improve the toughness and threshold of a single polymeric network. Polyacrylamide hydrogels have been selected as a model material. The polymer network is cured by two kinds of crosslinkers: a normal crosslinker and a light-degradable crosslinker. We characterize the pristine sample and light-treated sample by shear modulus, fracture toughness, fatigue threshold, and fractocohesive length. Notably, we apply light at the crack tip of a sample so that the light-sensitive crosslinkers degrade, resulting in a CTS sample with a softer and elastic crack tip. The pristine sample has a fracture toughness of 748.3 ± 15.19J/m2 and a fatigue threshold of 9.3J/m2. By comparison, the CTS sample has a fracture toughness of 2,774.6 ± 127.14J/m2 and a fatigue threshold of 33.8J/m2. Both fracture toughness and fatigue threshold have been enhanced by about four times. We attribute this simultaneous enhancement to stress de-concentration and elastic shielding at the crack tip. Different from the "fiber/matrix composite" concept and the "crystallization at the crack tip" concept, the CTS concept in the present work provides another option to simultaneously enhance the toughness and threshold, which improves the reliability of soft devices during applications.

Double Hydrogen‐bonding Reinforced High‐Performance Supramolecular Hydrogel Thermocell for Self‐powered Sensing Remote‐Controlled by Light

AbstractNon‐contact human‐machine interaction is the future trend for wearable technologies. This demand is recently highlighted by the pandemic of coronavirus disease (COVID‐19). Herein, an anti‐fatigue and highly conductive hydrogel thermocell with photo‐thermal conversion ability for non‐contact self‐powering applications is designed. Double hydrogen‐bonding enhanced supramolecular hydrogel is obtained with N‐acryloyl glycinamide (NAGA) and diacrylate capped Pluronic F68 (F68‐DA) via one‐step photo‐initiated polymerization. The supramolecular hydrogel can accommodate saturated electrolytes to fulfill the triple function of ionic crosslinking, heat‐to‐electricity conversion, and light response of thermocell. Eminently, the thermocell stands out by virtue of its high seebeck coefficient (‐2.17 mV K−1) and extraordinary toughness (Fatigue threshold ≈ 3120 J m−2). The self‐powering ability under the control of light heating is explored, and a model of a non‐contact “light‐remoted” sensor with self‐powered and sensing integrated performance remote‐controlled by light is constructed. It is believed that this study will pave the way for the non‐contact energy supply of wearable devices.

Low-intensity mixing process of high molecular weight polymer chains leads to elastomers of long network strands and high fatigue threshold.

Many polymer networks are prepared by crosslinking polymer chains. The polymer chains and crosslinkers are commonly mixed in internal mixers or roll mills. These intense processes break the polymer chains, lower viscosity, and ease mixing. The resulting polymer networks have short chains and a fatigue threshold of ∼100 J m-2. Here, we show that a low-intensity process, a combination of kneading and annealing, preserves long chains, leading to a network of polybutadiene to achieve a fatigue threshold of 440 J m-2. In a network, each chain has multiple crosslinks, which divides the chain into multiple strands. At the ends of the chain are two dangling strands that do not bear the load. The larger the number of crosslinks per chain, the lower the fraction of dangling strands. High fatigue threshold requires long strands, as well as a low fraction of dangling strands. Once intense mixing cuts chains short, each short chain can only have a few crosslinks; the strands are short and the fraction of dangling strands is high-both lower the fatigue threshold. By contrast, a low-intensity mixing process preserves long chains, which can have many crosslinks; the strands are long and the fraction of dangling strands is low-both increase the fatigue threshold. It is hoped that this work will aid the development of fatigue-resistant elastomers.

Effect of R load ratio on fatigue crack growth resistance of steels used in automotive applications: experimental results and use of performance prediction models

This research consisted in comparing the fatigue crack growth (FCG) performance of four HSLA/ AHSS steels used in automotive applications and with different microstructures, and the application of some prediction models for the da/dN versus ΔK traditional sigmoidal curve as a function of the R load ratio. FCG tests were carried out on C(T) test specimens with R-ratios varying between 0.03 and 0.7. Using the original and empirical methodology proposed by Paris and Erdogan to describe the da/dN-ΔK relationship, the results showed significant differences in function of microstructure, and a deleterious effect of R-ratio increase on the crack growth rate. In order to check existing methodologies based on physical considerations for predicting the fatigue behavior of materials and the effect of the R-ratio mainly in the fatigue threshold ΔKth region, the well-known crack closure model proposed by Elber, an approach using two parameters as a driving force for the crack growth proposed by Vasudevan and co-authors and a combination of these two models recently proposed by Zhu and co-authors were compared. The manifestation of crack closure and its qualitatively expected dependence on the R-ratio were verified for the studied steels, but the Elber model was not able to provide a master curve that accurately summarized the effect of the R-ratio on the sigmoidal fatigue curve of steels. The combined use of two critical thresholds, ΔKth* and Kmax*, for predicting fatigue crack growth according to the Vasudevan model also did not provide accurate results in evaluating the effect of the R-ratio. Regardless of the verified dispersions, there is a connection between the two-parameter methodology and crack closure, hence the model by Zhu and co-authors could be a promising alternative. However, this model also showed significant dispersions and was unable to create a master curve to adequately predict the effect of R-ratio on crack growth. Thus, it can be concluded that this research topic is still open, requiring a more in-depth phenomenological knowledge to predict the effect of the R-ratio on FCG.

Extremely strengthening fatigue resistance, elastic restorability and thermodynamic stability of a soft transparent self-healing network based on a dynamic molecular confinement-induced bioinspired nanostructure.

Soft self-healing materials are crucial for the development of next-generation wearable electronics that could function in dynamic environments and resist mechanical damage. However, several challenges remain, including fatigue fracture, poor elasticity, and thermodynamic lability, which significantly limit their practical applications. Here, with a model system of soft self-healing polyurea, we propose a molecular engineering strategy of transforming inherently fragile materials with an island-like structure into resilient ones with a bicontinuous nanophase separation structure using 2-ureido-4-pyrimidinone (UPy) supramolecular motifs as structural regulators. The dynamic and continuous hard domains modified by UPy formed a repairable bicontinuous network similar to those of the reticular layer in animal dermis. This design allows for a simultaneous and tremendous improvement in the fatigue threshold (34.8-fold increase), elastic restorability (the maximum elongation for full dimensional recovery increasing from 6 times to 13 times), and thermodynamic stability (4 orders of magnitude improvement in the characteristic flow transition relaxation time), without significantly compromising the compliance, autonomous self-healing, and optical transparency. These mechanical and thermodynamic improvements address current limitations in unfilled soft self-healing materials as reliable substrates for transparent strain-electronics.

Low Hysteresis and Fatigue-Resistant Polyvinyl Alcohol/Activated Charcoal Hydrogel Strain Sensor for Long-Term Stable Plant Growth Monitoring.

Flexible strain sensor as a measurement tool plays a significant role in agricultural development by long-term stable monitoring of the dynamic progress of plant growth. However, existing strain sensors still suffer from severe drawbacks, such as large hysteresis, insufficient fatigue resistance, and inferior stability, limiting their broad applications in the long-term monitoring of plant growth. Herein, we fabricate a novel conductive hydrogel strain sensor which is achieved through uniformly dispersing the conductive activated charcoal (AC) in high-viscosity polyvinyl alcohol (PVA) solution forming a continuous conductive network and simple preparation by freezing-thawing. The as-prepared strain sensor demonstrates low hysteresis (<1.5%), fatigue resistance (fatigue threshold of 40.87 J m−2), and long-term sensing stability upon mechanical cycling. We further exhibit the integration and application of PVA-AC strain sensor to monitor the growth of plants for 14 days. This work may offer an effective strategy for monitoring plant growth with conductive hydrogel strain sensor, facilitating the advancement of agriculture.

Lactate Threshold and Psychomotor Fatigue Threshold in Hot Conditions: Suggestions for Soccer Players Participating in the Qatar World Cup 2022.

The study aimed at finding relationships between lactate threshold and psychomotor fatigue threshold during incremental exercise in thermo-neutral climate conditions and conditions for the 2022 FIFA World Cup in Qatar simulated in an environmental test chamber. The study included 24 soccer players aged 21.02 ± 3.22 years old. The following procedures were performed: The incremental exercise test to mark lactate concentration-LA (mmol·l-1); Psychomotor test to determine choice reaction time; Designation of the lactate threshold (TLA) and psychomotor fatigue threshold (TPF). Climate conditions: The procedure was performed twice in the climatic chamber: (1) in thermo-neutral conditions-TNC (ambient temperature 20.5 °C and relative air humidity 58.7%), (2) after 7 days-in Qatar conditions-QC (28.5 ± 1.92 °C) and (58.7 ± 8.64%). It was confirmed that the TPF, which reflects the highest efficiency of CNS functioning, occurs at a higher running speed than the TLA. The temperature of 28.5 °C with 58.7% humidity, which is the lower limit of heat stress, causes the psychomotor fatigue threshold to appear at a lower running speed than in thermoneutral conditions. The data recorded in this work may help to understand the specificity of physiological and psychomotor reactions to various climatic conditions.

Automated and Continuous Fatigue Monitoring in Construction Workers Using Forearm EMG and IMU Wearable Sensors and Recurrent Neural Network.

About 40% of the US construction workforce experiences high-level fatigue, which leads to poor judgment, increased risk of injuries, a decrease in productivity, and a lower quality of work. Therefore, it is essential to monitor fatigue to reduce its adverse effects and prevent long-term health problems. However, since fatigue demonstrates itself in several complex processes, there is no single standard measurement method for fatigue detection. This study aims to develop a system for continuous workers' fatigue monitoring by predicting the aerobic fatigue threshold (AFT) using forearm muscle activity and motion data. The proposed system consists of five modules: Data acquisition, activity recognition, oxygen uptake prediction, maximum aerobic capacity (MAC) estimation, and continuous AFT monitoring. The proposed system was evaluated on the participants performing fourteen scaffold-building activities. The results show that the AFT features have achieved a higher accuracy of 92.31% in assessing the workers' fatigue level compared to heart rate (51.28%) and percentage heart rate reserve (50.43%) features. Moreover, the overall performance of the proposed system on unseen data using average two-min AFT features was 76.74%. The study validates the feasibility of using forearm muscle activity and motion data to workers' fatigue levels continuously.

Crack growth in conventionally manufactured pure nickel, titanium and aluminum and the cold spray additively manufactured equivalents

• Illustrates that crack growth in conventionally manufactured as well as CSAM Ni, Ti and Al parts can be characterized by a single governing equation. • Extends the application of the Hartman-Schijve equation to these pure metals. • Illustrates that crack growth in conventionally manufactured and CSAM parts can be represented by an identical curve by allowing for differences in the fracture toughness and fatigue threshold. It has recently been shown that when the d a /d N versus Δ K curves associated with crack growth in conventionally manufactured, additively manufactured (AM), and cold spray additively manufactured (CSAM) 316L stainless steel are replotted with d a/ d N expressed as a function of the Schwalbe crack driving force (Δ κ ), then the various different curves collapsed onto a single master curve. This study reveals that this phenomenon also arises for crack growth in titanium, nickel, and aluminum. In each case, the d a/ d N versus Δ κ relationship is shown to be independent of whether the specimen was conventionally manufactured or produced by CSAM.

Critical power as a fatigue threshold in sports: A scoping review

Critical power derived from the P-D curve in high intensity exercise (heavy and severe intensity) depicts the work capacity, exercise tolerance or resistance to fatigue. Critical power demarcates heavy intensity domain (where VO 2 can stabilize) from severe intensity domain (where VO 2 does not stabilize). The level of fatigue is based on the limit and extends of the metabolic state of the body. Critical power depicts the maximal metabolic steady state as critical power distinguishes the non-fatiguing work rates from fatiguing work rates. Although critical power proves to be the ultimate fatigue threshold, it is often ignored pragmatically despite high correspondence to recovery, fatigue and performance. Literature was searched on Google Scholar, Pubmed, Scopus and Medline. The keywords used were “critical power”, “fatigue”, “fatigue threshold”, “high intensity exercise” and “atheletes” or “players” or “sportsperson” since inception.. The articles with full text available in English were used to prepare this review. This review is structured based on the pertinent literature for the basic concept and simplified explanation of critical power to cater to the trainers, coaches and athletes. This review provides the overview of the different methods and models of critical power estimation based on the bioenergetics of the body. There are several different metabolic thresholds in exercise physiology, this review enumerates how critical power relates and differs from different metabolic thresholds and accounts for the fatigue process caused by high-intensity exercise. This review also entails all the recent discoveries around critical power and future prospects for research on this topic. This review concludes that critical power is not just a parameter for assessing the exercise tolerance in athletes but also an aspect to look out for in the trainings and competitions. La puissance critique dérivée de la courbe P-D dans un exercice de haute intensité (intensité forte et sévère) représente la capacité de travail, la tolérance à l’exercice ou la résistance à la fatigue. La puissance critique délimite le domaine d’intensité élevée (où le VO 2 peut se stabiliser) du domaine d’intensité sévère (où le VO 2 ne se stabilise pas). Le niveau de fatigue est lié à la limite des possibilités métaboliques de l’organisme. La puissance critique représente l’état d’équilibre métabolique maximal, car la puissance critique distingue les cadences de travail non fatigantes des cadences de travail fatigantes. Bien que la puissance critique se révèle être le seuil ultime de fatigue, elle est souvent ignorée de manière pragmatique malgré une correspondance élevée avec la récupération, la fatigue et les performances. Les articles ont été recherchés sur Google Scholar , Pubmed , Scopus et Medline . Les mots-clés utilisés étaient « puissance critique et athlètes ou joueurs ou sports ou exercice de haute intensité », « puissance critique et fatigue ». Les articles avec texte intégral disponible en anglais ont été utilisés pour préparer cette revue. Cette revue est structurée sur la base de la littérature pertinente pour le concept envisagé et l’explication de la notion de pouvoir critique pour répondre aux besoins des entraîneurs, des entraîneurs et des athlètes. Cette revue donne un aperçu des différentes méthodes et modèles d’estimation de la puissance critique basée sur la bioénergétique du corps. Il existe plusieurs seuils métaboliques différents dans la physiologie de l’exercice, cette revue énumère comment la puissance critique est liée et diffère des différents seuils métaboliques et rend compte du processus de fatigue causé par un exercice de haute intensité. Cette revue comprend également toutes les découvertes récentes autour de la puissance critique et des perspectives d’avenir pour la recherche sur ce sujet. Cette revue conclut que la puissance critique n’est pas seulement un paramètre pour évaluer la tolérance à l’exercice chez les athlètes, mais aussi un élément à surveiller dans les entraînements et les compétitions.

Kinetic model for prediction of subcritical crack growth, crack tip relaxation, and static fatigue threshold in silicate glass

Prediction of brittle fracture of amorphous oxide glasses continues to be a challenge due to the existence of multiple fracture mechanisms that vary with loading conditions. To address this challenge, we present a model for all three regimes of crack growth in glasses. Regimes I and III are controlled by Arrhenius processes while regime II is transport controlled along with a simple Arrhenius model for viscoelastic stress relaxation. Through dimensional arguments and physical reasoning, we propose a single mechanism which underlies both regime III subcritical crack growth and near-crack-tip viscoelastic relaxation. By combining the subcritical crack growth and viscoelastic models we obtain a prediction for a threshold stress intensity, Kth, below which stresses around the crack relax faster than it propagates. For stress intensity KI<Kth, no subcritical crack growth is predicted to occur, allowing for the design of stable glass systems. The prediction is compared to measured subcritical fracture threshold data for soda-lime silica glasses.

Fatigue crack tip corrosion processes and oxide induced closure

This paper reviews the corrosion and hydrolysis reactions that occur inside a fatigue crack at ambient temperatures and pressures in humid air and aqueous solutions. This study examines the individual reaction steps, intermediate phases formed, and the time required for the metal ions to transition into hard oxide phases. This study also finds that when a fatigue crack closes at ambient temperatures, the corrosion products inside the crack should consist of thin (≈2 nm) hard oxide films on the fracture surfaces and viscous layers of water with metal ions in various states of the transition from aqueous ions to stable end-product phases, but with insufficient strengths to resist load transfer at the crack tip. This analysis assumes that metal ion complexes form at the crack tip and transition toward the end-product phases in the wake of the crack in a manner analogous to that reported for plane surfaces exposed to humid air and aqueous solutions. It is concluded that the contribution of the viscous layers to an oxide induced crack closure (OICC) mechanism should be negligible. The impact of this finding on the interpretation of R-ratio effects on fatigue crack threshold and oxide thickness measurements is discussed. The OICC mechanism should be possible at high temperatures and in the near threshold fatigue crack growth region where hard oxides can grow to sizes relevant to the cyclic crack opening displacement (COD).

Fatigue Threshold Analysis of Adhesives: Displacement Control vs. Load Control Strategy

The aim of this paper is to study the response of a two-part polyurethane-resin adhesive under quasi-static and fatigue loading conditions, to compare load control and displacement control approaches for the mode I fatigue threshold analysis of the tested material. To achieve this, double cantilever beam (DCB) joints were manufactured and tested. For the post-processing of the raw data, a compliance-based beam method was used. Out of this analysis, R curves and Paris law curves were obtained. Both approaches showed a similar Paris law slope meaning a low sensibility of the crack growth rate between them. As the displacement control load decreases gradually during the test, it can give more precise threshold energy than the load control technique.