Fatigue Analysis of Stripper Bolt Under Combined Loading for Improvement of Stamping Die Design

1986 ◽  
Vol 108 (2) ◽  
pp. 222-229
Author(s):  
Sang Hoon Lee
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Impact Load ◽  
Rectangular Pulse ◽  
Die Design ◽  
Combined Loading ◽  
Element Analysis ◽  
Mass System ◽  
Stamping Die ◽  
Stamping Dies

A common problem of fatigue failure of stamping dies was experienced during the stamping operation with socket-head screws. In order to establish a design standard for the stripper bolt, a methodology for determination of the loads and the fatigue strength of the stripper bolt was developed. Stresses due to an impulsive load and a rectangular pulse were calculated based on a simplified spring mass system and the appropriate corrections were made to elaborate the solution. This approximate solution was validated by a finite element analysis. The stripper bolt should have an infinite fatigue life to survive a half million stamping operations. The fatigue problem involves a stress concentration with combined mean and alternating stresses. The Gerber parabola and the residual stress method were employed to treat the combined loading and the stress concentration. In order to enhance the fatigue life of the stripper bolt, a cushion is introduced at the surface where an impact load is applied. The cushion is found very effective in improving the fatigue life of the stripper bolt. An interactive computer program was developed as a tool for designing stamping dies.

Development of Design Curve for Sweepolet Subjected to Acoustic Induced Vibration

2016 ◽  
Author(s):  
Yuqing Liu ◽  
Philip Diwakar ◽  
Dan Lin ◽  
Ismat Eljaouhari ◽  
Ajay Prakash
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Fatigue Failure ◽  
High Stress ◽  
Peak Stress ◽  
Acoustic Energy ◽  
Piping System ◽  
Element Analysis ◽  
Design Curve ◽  
High Stress Concentration

High acoustic energy has the potential to cause severe Acoustic Induced Vibration (AIV) that leads to fatigue failure at high stress concentration regions such as fittings in a piping system. Sweepolet fittings have been extensively used as mitigation to counteract the risk of fatigue failure caused by AIV. The advantages of a sweepolet are its integrally reinforced contoured body and low stress concentration. However, there are inconsistencies in published standards and regarding the design limits for sweepolet subjected to AIV. In this paper, Finite Element Analysis is conducted to simulate high frequency pipe shell wall vibration caused by acoustic energy inside the pipe. Peak stress and the associated minimum fatigue life are calculated for sweepolet and sockolet under the same acoustic excitation. By comparing the stress level to that of a sockolet whose design limit to AIV had been published, the design curve and fatigue life equation for sweepolet are developed.

scholarly journals High cycle fatigue life estimation of AlSi10Mg processed by laser powder bed fusion

2018 ◽  
Vol 188 ◽  
pp. 03015 ◽  
Author(s):  
Even W. Hovig ◽  
Amin S. Azar ◽  
Martin F. Sunding ◽  
Knut Sørby ◽  
Mohammed M'hamdi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Surface Properties ◽  
High Cycle Fatigue ◽  
Material Surface ◽  
Powder Bed Fusion ◽  
Cycle Fatigue ◽  
Laser Powder Bed Fusion ◽  
Element Analysis ◽  
Powder Bed

Fatigue life is known to be dependent on the surface properties of the material. Surface roughness provokes local stress concentration and cause crack initiation even at minute cyclic loads. In laser powder bed fusion, the as-built surfaces show variable roughness depending on the orientation of the specimens with respect to the build plate. In order to analyse the effect of build angle on surface properties, flat tensile specimens were produced from an AlSi10Mg alloy in a Concept Laser M2 Cusing machine. Seven specimens were arranged from flat to perpendicular with respect to the build plate at 15° intervals. The as-built surface topography of each specimen was characterised by white light interferometry. Two methods for calculating the stress concentration factor for high cycle fatigue simulation were developed. The presence of subsurface porosity was a crucial factor in expanding the stress concentration as demonstrated by finite element analysis.

Fatigue Assessment of Pipeline With Plain Dents Under Cyclic Pressure Loading Using Finite Element Method

2016 ◽  
Author(s):  
Michael Durowoju ◽  
Yongchang Pu ◽  
Simon Benson ◽  
Julia Race
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Material Strength ◽  
Pipe Material ◽  
Element Analysis ◽  
Fatigue Assessment ◽  
Pipe Geometry ◽  
Dent Depth

One of the major challenges faced in fatigue assessment today is determining the stress concentration factor ‘SCF’ associated with the dents, which are used with appropriate SN curves to determine the fatigue life. This historically has been determined empirically or by using finite element analysis. This paper presents finite element analysis on a parametric range of industry pipes (both offshore and onshore) to extract SCF data used for fatigue assessment. The parametric dataset focuses on the effects of pipe geometry, dent geometry, material properties and pressure cycling on the prediction of the fatigue life. This parametric dataset will eventually be used to develop an algorithm for fatigue prediction using an artificial neural network. Two types of indenters (Dome and Bar) are used to simulate circumferential and longitudinal dents. Four different dent depths ranging from 2% d/D to 10% d/D are also simulated to investigate the effect of dent geometry. Four different pipe grades (X42, X65, X80 and X100) are analyzed to investigate the effect of pipe materials on dent fatigue. Similarly, eight pipes with different diameter to thickness ratio D/t ranging from 18–96 are analyzed to investigate the effect of pipe geometry. Stresses are computed at both 50% SMYS and 72% SMYS to investigate the effect of pressure variation. The results from this study indicate that longitudinal dents have higher stress concentrations compared to circumferential dents of similar dent depth. Results also indicate that the re-round dent depth (i.e. dent depth after pressurization) increases with increasing D/t and increasing dent depth. Similarly, the pipe material has a major effect on the fatigue life. Pipes with higher material strength have higher stress concentration compared to pipes with lower strength of similar dent depth. The stress concentration factors SCF associated with the dents are then computed.

Fatigue Life Prediction of Notched Specimen Based on Stress Gradient

2020 ◽  
Author(s):  
Masahiro Takanashi
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Life Prediction ◽  
Notch Root ◽  
Stress Gradient ◽  
Peak Stress ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Notched Specimen ◽  
Gradient Approach

Abstract Many failure accidents have indicated fatigue as the primary cause for the failure of a machine or structure. In general, the origin of failure is a structural discontinuous part such as a welded joint or a notched member that causes stress concentration. While designing such a component, a finite element analysis (FEA) has to be conducted, and the peak stress has to be compared with a design fatigue curve obtained from small-sized specimens to evaluate whether the component satisfies the design life. However, it is known that a fatigue life prediction at a stress concentration part based on a peak stress always provides an excessively conservative estimation. This is due to the stress gradient of the component. This paper discusses the stress-gradient approach to eliminate the conservatism and rationalize a fatigue design. Using literature test data, the relationship between the stress gradient calculated using FEA, and the fatigue strength reduction ratio was determined. Later, a fatigue test was conducted on a notched specimen of low-alloy steel to verify the stress-gradient approach, and the fatigue life of the notched specimen was predicted considering the stress gradient at the notch root. The predicted fatigue life agreed well with the experimental results.

Fitness for Service of Dents Associated With Metal Loss due to Corrosion

2014 ◽  
Author(s):  
Hans Olav Heggen ◽  
Joe Bratton ◽  
David Kemp ◽  
Jun Liu ◽  
Jason Austin
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Maximum Stress ◽  
Dynamic Pressure ◽  
Equivalent Stress ◽  
Metal Loss ◽  
General Effect ◽  
Element Analysis ◽  
Pressure Cycling ◽  
Pressure Cycle

Current federal regulations in the U.S. require excavation of all dents associated with metal loss due to corrosion identified through in line inspection surveys. Once a dent has been found to be associated with metal loss through excavation, there is little guidance to determine the serviceability of the anomaly. Past research has provided methodologies to assess the fatigue life of plain dents, considering the shape of the dent, but there are no widely accepted assessment methodologies to predict the effect of associated metal loss due to corrosion on the fatigue life of dents. This paper focuses on the fitness for service of dents associated with metal loss, particularly corrosion in dents. Currently, fitness for service assessments of plain dents provide an estimated remaining life of a dent based on the geometry of the dent and current pressure cycling of the pipeline. Dynamic pressure cycling at each dent location is estimated using the upstream and downstream pressure cycle data, elevation, and distance along the pipe. The dynamic pressure cycle data at each dent is then converted into equivalent stress cycles based on the results of rainflow cycle counting. Finite element analysis (FEA) of a dent without metal loss and with metal loss is performed to compare the maximum stress concentration areas. The FEA program Abaqus is used with solid elements to model the dents. The differences between maximum stress concentration areas is compared for a matrix of extent of metal loss, and orientation of metal loss to analyze the general effect of metal loss and the interaction of metal loss in a dent. The stress concentration areas of dents without metal loss and with metal loss are then applied to current fatigue assessment methodologies provided in API 579 to analyze the effect of metal loss on the fatigue life of dents.

Effect of Plastic Hardening Models on Fatigue Life Simulation of Pipeline Elbows Under Operating Pressure and Cyclic Bending

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Fatigue Life ◽  
Numerical Study ◽  
Kinematic Hardening ◽  
Combined Loading ◽  
Operating Pressure ◽  
Element Analysis ◽  
Hardening Model ◽  
Hardening Models ◽  
Plastic Hardening ◽  
Plane Bending

Abstract This paper presents a numerical study of plastic hardening models used in the stress, strain, and fatigue life simulations of a pipeline elbow under operating pressure and cyclic in-plane bending. To determine more accurate stresses, strains, and fatigue life of the elbow in cyclic loading, the material plastic hardening response and the Bauschinger effect need to be considered properly in the numerical simulation. The isotropic, kinematic, and combined isotropic/kinematic hardening models are, thus, evaluated in the elastic-plastic finite element analysis (FEA) of a benchmark beam. On this basis, those plastic hardening models are applied to simulate the elbow under combined loading of constant internal pressure and cyclic in-plane bending. With the FEA results and selected fatigue models that are commonly used in the pipeline industry, fatigue life of the elbow is predicted for each hardening model. As such, the appropriate plastic hardening model and fatigue life model to predict fatigue life of the elbow are determined.

An Analysis of Drawing Process in Stamping Die Design for the Wheel Hub

2010 ◽  
Vol 142 ◽  
pp. 107-111
Author(s):  
Bai Liu
Keyword(s):  
Numerical Simulation ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Flow ◽  
Process Parameters ◽  
Die Design ◽  
Drawing Process ◽  
Element Analysis ◽  
Stamping Die ◽  
Stamping Process

Based on Finite Element Analysis (FEA) module of Dynaform software, the paper made numerical simulation of a wheel hub’s stamping process in the method of elastic-plastic flow, pointed out the behavior of deformation of stamping process, predicted and prevented stamping defect such as crack in the process, and calculated the degree of resilience. Consequently three forming numerical simulation schemes have been designed respectively, more feasible process parameters has been achieved in comparison with the features of each scheme.

Finite Element Analysis of Dual-Frequency Vibrating Screen

2012 ◽  
Vol 479-481 ◽  
pp. 2124-2128 ◽  
Author(s):  
Yong Jun Hou ◽  
Pan Fang ◽  
Lian Zeng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
High Frequency ◽  
Element Model ◽  
Dual Frequency ◽  
Element Analysis ◽  
Vibrating Screen ◽  
Sufficient Strength

In order to study the stress distribution of dual-frequency vibrating screen and ensure the screen box has sufficient strength and longevity, a finite element model of dual-frequency vibrating screen was built, and the stress, modes and fatigue life of the screen box were analyzed. The results indicate that, the stress concentration appears at the contacting parts between the crossbeam and the stiffener of motor seat, the crossbeam, L-type stiffening plate, baffle of material added and screen box. The middle of crossbeam and the L-type stiffening plate are weaker parts of fatigue, they are easily fatigue failure under high frequency vibration.

Fatigue Life Estimation of Modified Railroad Bearing Adapters for Onboard Monitoring Applications

2015 ◽  
Author(s):  
Alexis Trevino ◽  
Arturo A. Fuentes ◽  
Constantine M. Tarawneh ◽  
Joseph Montalvo
Keyword(s):  
Finite Element ◽  
Cast Iron ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Impact Load ◽  
Element Analysis ◽  
Operational Conditions ◽  
Operational Life ◽  
Monitoring Applications ◽  
Railroad Bearing

This paper presents a study of the fatigue life (i.e. number of stress cycles before failure) of Class K cast iron conventional and modified railroad bearing adapters for onboard monitoring applications under different operational conditions based on experimentally validated Finite Element Analysis (FEA) stress results. Currently, freight railcars rely heavily on wayside hot-box detectors (HBDs) at strategic intervals to record bearing cup temperatures as the train passes at specified velocities. Hence, most temperature measurements are limited to certain physical railroad locations. This limitation gave way for an optimized sensor that could potentially deliver significant insight on continuous bearing temperature conditions. Bearing adapter modifications (i.e. cut-outs) were required to house the developed temperature sensor which will be used for onboard monitoring applications. Therefore, it is necessary to determine the reliability of the modified railroad bearing adapter. Previous work done at the University Transportation Center for Railway Safety (UTCRS) led to the development of finite element model with experimentally validated boundary conditions which was utilized to obtain stress distribution maps of conventional and modified railroad bearing adapters under different service conditions. These maps were useful for identifying areas of interest for an eventual inspection of railroad bearing adapters in the field. Upon further examination of the previously acquired results, it was determined that one possible mode of adapter failure would be by fatigue due to the cyclic loading and the range of stresses in the railroad bearing adapters. In this study, the authors experimentally validate the FEA stress results and investigate the fatigue life of the adapters under different extreme case scenarios for the bearing adapters including the effect of a railroad flat wheel. In this case, the flat wheel translates into a periodic impact load on the bearing adapter. The Stress-Life approach is used to calculate the life of the railroad bearing adapters made out of cast iron and subjected to cyclic loading. From the known material properties of the adapter (cast iron), the operational life is estimated with a mathematical relationship. The Goodman correction factor is used in these life prediction calculations in order to take into account the mean stresses experienced by these adapters. The work shows that the adapters have infinite life in all studied cases.

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

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