Coffin-Manson Method Research Articles

Tensile efficiency and fatigue life of similar and dissimilar carbon steel joints subjected to rotary friction welding

Rotary friction welding (RFW) is a solid-state welding method that can address the melting point limitation of other welding types; however, the welded area remains at risk of failure due to fatigue during operation. Fatigue failure is difficult to detect and predict, making it a critical failure mode in engineering. Although many fatigue life prediction methods are available, they do not consider the impact of RFW parameters (such as pressure, speed, and friction time) on fatigue strength. Owing to their good mechanical properties and commercial viability, carbon steel of grades C35 and C45 is commonly applied to manufacture main parts in the automotive industry. This study centers on employing RFW to join C35 and C45, representing the first-ever instance of using this technique to weld them together. The primary goal of RFW for C35 and C45 is to construct optimum parts that meet specific design requirements and have a long fatigue life. Findings showed C45–C45 joints (77 %) were more tensile-efficient than C35–C35 joints (73 %). Dissimilar C35–C45 joints reached 60 % of C45 base metal and 76 % of C35 base metal in terms of tensile efficiency. RFW welds had lower tensile strength than their base metals. Optimal results came at 35 MPa friction pressure and 8–12 s friction time for both similar and dissimilar RFW joints using the Coffin–Manson method, dissimilar C33–C45 joint fatigue life improved by over 85 %, aligning C35 and C45 engineering aspects. SEM microstructure analysis showed two regions: non-deformed (NDZ) and plastically deformed (PDZ), with broader PDZ indicating better tensile strength. These findings enhance RFW's efficiency, promoting automotive part longevity and safety.

Contact fatigue life estimation for asymmetric helical gear drives

The numerical model for an asymmetric helical gear is developed through analytical equations, and the contact fatigue life (CFL) is estimated based on the Basquin and Coffin-Manson method. Further, the numerically simulated CFL and bending fatigue life are validated with the experimental results based on the literature. By employing the proposed model, the significant asymmetric helical gear parameters of helix angle, gear ratio, teeth number, module, face width, pressure angle and coefficient of friction are estimated for customized power transmission by improving the CFL. Finally, it is revealed that an asymmetric helical gear exhibits enhanced CFL over symmetric helical gear.

Low Cycle Fatigue Life Evaluation According to Temperature and Orientation in Nickel-Base Superalloy

Components of gas turbines must be extremely resistant to high temperatures, high stresses, high-temperature corrosion, and erosive environments. The materials used in these environmental conditions are mainly nickel-based superalloys. In this study, the low-cycle fatigue of the nickel-based superalloy Inconel 792 was examined. The total strain range of a gas turbine between 760 °C and 870 °C was considered as the parameter representing the actual gas turbine operation. In addition, tests were performed using a trapezoidal waveform of the total strain to reflect the operation-stop conditions of a gas turbine with frequent shutdowns. The results of the fatigue test were compared with the Coffin–Manson method and energy method. The fractured surface was analyzed using a scanning electron microscope (SEM).

단결정 니켈기 초내열합금 CMSX-4의 고온 저주기 피로특성

Isothermal low cycle fatigue (LCF) behavior of a crystal nickel-based superalloy CMSX-4, a material for high-pressure turbine first stage rotor blade, was investigated at elevated temperatures. Strain-controlled LCF tests were performed under various test conditions, such as mechanical strain amplitude. Stress response and cyclic deformation were investigated, and equations of LCF life prediction were derived through the Coffin-Manson method. In addition, fatigue-induced fracture mechanism and microstructural evolution were investigated, using scanning electron microscopy (SEM). Results revealed that cyclic behavior of the CMSX-4 superalloy, was characterized by cyclic softening with increasing number of cycles at 800oC and 900oC. LCF of the CMSX-4 superalloy at 800oC and 900oC could be affected mainly by elastic damage in fatigue processing. Fatigue cracks were initiated in the surface oxide layer of the specimen. The plane of fracture surface was tilted toward 001 direction. The fatigue fracture mechanism was quasi-cleavage fracture at 800oC and 900oC. In all broken specimens, the γˊ phase morphology maintained cuboidal shape.

Hold Time-Low Cycle Fatigue Behavior of Nickel Based Hastelloy X at Elevated Temperatures

Hastelloy X, a material used in gas turbines, is subject to complex damage because of creep and fatigue in a high temperature environment during the operation of gas turbines. Although the low cycle behavior of Hastelloy X has been widely investigated, the number of studies focusing on the actual operating conditions of the gas turbine is limited. In this study, the total strain range of the gas turbine at 760 °C and 870 °C was considered as a parameter of the actual gas turbine operation. In addition, tests were performed with a trapezoidal waveform of the total strain to reflect the operation—stop status of the gas turbine with frequent shutdown times. The results of the fatigue test were studied with the Coffin-Manson method and the lifetime prediction equation was derived based on the data. Fractography was performed using scanning electron microscopy (SEM) observation.

Simulation study on thermo-fatigue failure behavior of solder joints in package-on-package structure

In this work, the simulating analysis of PoP structure under the temperature range from 0°C to 125°C is carried out using direct thermal-cycle analysis and Coffin-Manson method. The results show that the maximum accumulating inelastic hysteresis energy appears on the solder ball in the bottom fine-pitch ball grid array (FBGA) structure. The thermal-fatigue crack initiates in the two symmetrical corners of solder ball in FBGA structure. The thermal-fatigue damage evolves fast in the outer row corner's balls then slowly propagates into the inner row balls in FBGA structure. By analyzing the failure data of solder balls, a thermal-fatigue failure criterion is defined where the critical failure probability value is about 80%.

A study of high temperature low cycle fatigue life prediction for two superalloys

The high temperature low cycle fatigue tests of DZ22 superalloy and K403 superalloyare carried out under strain controlled. The low cycle fatigue test data of DZ22superalloy at 850℃ and K403 superalloy at 750℃ are processed by Coffin-Mansonmethod. When experimental data is processed, negative or small plastic strain valuesoften appear and the results of life prediction fail to meet the needs of the designer. Inorder to solve the problem, a new method based on stress fatigue and Coffin-Mansonmethod is developed, the results of life prediction are given by using new method atthe same time. The results showed that new method is more accurate than the Coffin-Manson method. The life prediction capability of two methods for DZ22 superalloyproves more effective than K403 superalloy.

코발트기 초내열합금 ECY768의 고온 저주기피로 거동

The Co-base super heat resisting alloy ECY768 is employed in gas turbine because of its high temperature strength and oxidation resistance. The prediction of fatigue life for superalloy is important for improving the efficiency. In this paper, low cycle fatigue tests are performed as variables of total strain range and temperature. The relations between strain energy density and number of cycle to failure are examined in order to predict the low cycle fatigue life of ECY768 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

Characterization of Cut-Edges for Improved Automotive Chassis and Suspension Fatigue CAE Life Predictions

The durability of safety-critical automotive vehicle steel structures has been observed to be influenced significantly by the condition of the component’s cut-edge properties. The importance of the mechanical cut-edge properties on structural durability has been observed due to surface imperfections generated during the cutting process. These then become the preferred initiation sites for fatigue cracks due to the increased intensity of stress applied to a structure. The current work outlines the development of an improved finite element (FE)-based life prediction method, based on strain-life fatigue data of S355MC steel cut-edges. The resulting best method of predicting fatigue lives of cut-edges using the Coffin–Manson method has been determined as providing the best means for predicting the durability of high strength steel components. This process has been validated using a bespoke laboratory test component representative of those in automotive chassis and suspension assemblies. The outcome of this work is that it allows increased reliance on FE life predictions rather than extensive physical laboratory testing.

LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

초내열합금 GTD-111의 고온 저주기피로 수명예측

The Ni-base super-heat-resistant alloy, GTD-111, is employed in gas turbines because of its high temperature strength and oxidation resistance. It is important to predict the fatigue life of this superalloy in order to improve the efficiency of gas turbines. In this study, low-cycle fatigue tests are performed as variables of total strain range and temperature. The relationship between the strain energy density and number of cycles to failure is examined in order to predict the low-cycle fatigue life of the GTD-111 superalloy. The fatigue life predicted by using the strain-energy methods is found to coincide with that obtained from the experimental data and from the Coffin-Manson method.

Astudy on life prediction of low cycle fatigue in superalloy for gas turbine blades

A more accurate life prediction for gas turbine blade takes into account the material behaviour under the Low Cycle Fatigue cycles normally encountered in turbine operation. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of superalloy at different temperatures. The fatigue lives that are predicted by Coffin-Manson method and strain energy methods are compared with the measured fatigue lives at different temperatures.

니켈기 초내열합금 IN738LC의 고온 저주기피로 거동

니켈기 초내열합금은 고온 강도를 지속적으로 증가시키며 현재 비행기 엔진, 선박 엔진 및 발전용 가스터빈 고온 부품 등을 만드는 가장 중요한 소재로 오래전부터 사용되어져 왔다. 이러한 부품의 수명을 연장하기 위해서는 사용 환경과 유사한 조건에서의 피로수명 예측이 매우 중요하다. 따라서 본 연구에서는 가스터빈 블레이드 소재인 니켈기 초내열합금 IN738LC에 대하여 실제운전환경과 유사한 조건을 설정하여 다양한 변형률 범위와 온도에서 시험을 수행하였다. 저주기 피로수명을 예측하기 위하여 변형률 에너지 밀도와 파단 사이클과의 관계를 사용하였다. 수명의 예측은 시험결과를 토대로 변형률 에너지법과 Coffin-Manson법에 의하여 예측을 하였다.

An Experimental Study on Low Cycle Fatigue of Inconel 617 Super Alloy

Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.

Multiaxial fatigue and failure analysis of helical compression springs

Multiaxial fatigue criteria are applied to the analysis of helical compression springs. The critical plane approaches, Fatemi–Socie and Wang–Brown, and the Coffin–Manson method based on shear deformation, were used to predict fatigue lives of the springs under constant amplitude loading. Experimental fatigue lives are compared with the multiaxial fatigue criteria predictions. The stress analysis was carried out in the finite element code ANSYS, and the multiaxial fatigue study was performed using the fatigue software nCode. A failure analysis was conducted in order to determine the fatigue crack initiation point and a comparison of that location with the most damaged zone predicted by the numerical analysis is made. The Fatemi–Socie critical plane approach gives a good prediction of fatigue life. While the Wang–Brown criterion overestimates spring fatigue life, the Coffin–Mason model gives conservative results.

A study of creep-fatigue life prediction using an artificial neural network

In this study, using AISI 316 stainless steel, creep-fatigue tests were carried out under various test conditions (different total strain ranges and hold times) to verify the applicability of the artificial neural network method to creep-fatigue life prediction. Life prediction was also made by the modified Coffin-Manson method and the modified Ostegren method using 21 data points out of a total 27 experimental data points. The six verification data points were carefully chosen for the purpose of evaluating the predictability of each method. The predicted lives were compared with the experimental results and the following conclusions were obtained within the scope of this study. While the creep-fatigue life prediction by the modified Coffin-Manson method and the modified Ostegren method had average errors of 35.8% and 47.7% respectively, the artificial neural network method had only 15.6%. As a result, the artificial neural network method with the adaptive learning rate was found to be far more accurate and effective than any of the others. The validity of the artificial neural network method for life prediction checked with the six verification data points also proved to be very satisfactory.

Low Cycle Fatigue Life Prediction of Structural Steels(Fatigue 1)

Low cycle fatigue tests are performed on high strength structural steels that be developed for submarine material. The relation between absorbed plastic strain energy and numbers of cycle to failure is examined in order to predict the low cycle fatigue life of structural steels by using plastic strain energy method. The cyclic properties are determined by a least square fit techniques. The life predicted by the plastic strain energy method is found to coincide with experiment data and results obtained from the Coffin-Manson method. Also the cyclic behavior of structural steels is characterized by cyclic softening with increasing number of cycle at room temperature. Especially, low cycle fatigue characteristics and microstructural changes of structural steels are investigated according to changing tempering temperatures. In the case of PFS steels, the ε-Cu is formed in 550℃ of tempering temperature and enhances the low cycle fatigue properties.