Vibration Fatigue Assessment of Additive Manufactured Nickel Alloy With Inherent Damping

2020 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Luke Sheridan ◽  
Brian Runyon ◽  
Tommy George
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Vibration Suppression ◽  
Internal Surface ◽  
Powder Bed ◽  
Vibration Fatigue ◽  
Strain Stress ◽  
Internal Volume ◽  
Fatigue Failures ◽  
Damping Capability

Abstract The fatigue life behavior and internal surface conditions of inherently damped Additive Manufactured (AM) specimens subjected to vibration bending are under investigation. This study supports research that demonstrated 95% vibration suppression due to damping capability of AM components with 1–3% internal volume of unfused powder. The damping demonstrations have been carried out using laser powder bed fusion (LPBF) specimens of various thicknesses, lengths, and unfused internal powder configurations. In addition, damping is shown to be achievable with both nickel-based alloys and stainless steel specimens. Despite the promise of this method, the viability of fatigue performance is unknown. The following effort aims to address this structural integrity issue; specifically, this study explores whether internal pocket roughness or erosion caused by powder particle motion induces a fatigue life debit. These concerns are addressed by comparing the fatigue behaviors of unfused powder pocket and fully-fused nickel based alloy 718 specimens. Microscopy results confirmed a long suspected powder interaction phenomena as well as appearances of erosion. Furthermore, fractography supports that fatigue failures initiate near the surface of maximum strain/stress at porous features consistent with stock (non-optimized) LPBF process parameters.

Vibration Fatigue Assessment of Additive Manufactured Nickel Alloy with Inherent Damping

2021 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Luke Sheridan ◽  
Brian Runyon ◽  
Tommy George
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Vibration Suppression ◽  
Internal Surface ◽  
Powder Bed ◽  
Vibration Fatigue ◽  
Strain Stress ◽  
Internal Volume ◽  
Fatigue Failures ◽  
Damping Capability

Abstract The fatigue life behavior and internal surface conditions of inherently damped Additive Manufactured (AM) specimens subjected to vibration bending are under investigation. This study supports research that demonstrated 95% vibration suppression due to damping capability of AM components with 1-3% internal volume of unfused powder. The damping demonstrations have been carried out using laser powder bed fusion (LPBF) specimens of various thicknesses, lengths, and unfused internal powder configurations. In addition, damping is shown to be achievable with both nickel-based alloys and stainless steel specimens. Despite the promise of this method, the viability of fatigue performance is unknown. The following effort aims to address this structural integrity issue; specifically, this study explores whether internal pocket roughness or erosion caused by powder particle motion induces a fatigue life debit. These concerns are addressed by comparing the fatigue behaviors of unfused powder pocket and fully-fused nickel based alloy 718 specimens. Microscopy results confirmed a long suspected powder interaction phenomena as well as appearances of erosion. Furthermore, fractography supports that fatigue failures initiate near the surface of maximum strain/stress at porous features consistent with stock (non-optimized) LPBF process parameters.

Investigating Damping Performance of Laser Powder Bed Fused Components With Unique Internal Structures

2018 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Brian Runyon ◽  
Casey Holycross ◽  
Bryan Langley ◽  
...  
Keyword(s):  
Loading Rate ◽  
Vibration Suppression ◽  
Forced Response ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Thermal Distribution ◽  
Internal Structures ◽  
Internal Feature ◽  
Feature Optimization ◽  
Damping Capability

An additive manufacturing (AM) process has been used to fabricate beam components with unique internal geometries capable of reducing weight and inherently suppressing vibration of the structure. Using the laser powder bed fusion (LPBF) AM process, four unique designs are investigated to quantify and understand the damping effectiveness of this manufacturing concept. Forced-response tests are conducted to validate the damping capability of each internal design configuration. The effects of external geometry, thermal distribution associated with internal friction, strain amplitude, and loading rate dependence on damping performance are studied. The results of the studied beams are compared to the damping performance of a fully-fused, or solid baseline LPBF beam. With only 1–4% internal beam volume alteration, the four unique beams are capable of providing up to ten times damping into their respective systems compared to the baseline, solid beam. From the studies of different parameter effects on damping, the main mechanism for vibration suppression is identified. Validation of the vibration suppression physics allows for internal feature optimization via LPBF that can maximize damping effectiveness.

Experimental and Modeling Study of the Effect of Corrosion Pitting on Fatigue Failure Locations in Aircraft Components

2014 ◽  
Vol 891-892 ◽  
pp. 236-241 ◽  
Author(s):  
Bruce R. Crawford ◽  
Chris Loader ◽  
Qian Chu Liu ◽  
Timothy J. Harrison ◽  
P. Khan Sharp ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
Pitting Corrosion ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Gauge Section ◽  
Stress Concentration Factors ◽  
Corrosion Pits ◽  
The Cost ◽  
Fatigue Failures

It is well established that corrosion pits reduce the fatigue life and structural integrity of aluminum alloy aircraft components. A great deal of research has been conducted in this area in the last 20 years. This problem is not unique to aluminum alloys or aircraft however. Similar problems have been observed in the steel components of other engineered structures such as steel pipelines and steam turbine blades. However the effect of pitting corrosion on the probable location of fatigue failures has been overlooked. This is problematic as corrosion pits have caused fatigue failures in locations and components where they were unexpected, such as the trailing edge flap lug of the F/A 18 fighter aircraft. DSTO have called this problem ‘Corrosion Criticality’. This paper reports the development of Monte-Carlo models of how pitting corrosion affects the location of fatigue failures in two fatigue specimen geometries that have different stress concentration factors (kt). These specimens are a low-kt fatigue life specimen and a high-kt fatigue life specimen with three holes arranged along its centerline. The modeling results for the low-kt specimen are then compared with experimental results for that specimen. The low-kt model produces good estimates of fatigue life and of the probability of fatigue failure at any given location in the specimen’s gauge section. The process that will be followed to develop the high-kt model is outlined. The paper includes a discussion of using the Corrosion Criticality models to reduce the cost of corrosion maintenance by (i) identifying areas in which corrosion inspections are critical and (ii) identify aircraft components for which pitting corrosion will not be a threat to airworthiness during the life of an aircraft.

Quantification of vertical, lateral, and longitudinal fastener demand in broken spike track: Inputs to mechanistic-empirical design

2021 ◽  
pp. 095440972110307
Author(s):  
Marcus S Dersch ◽  
Matheus Trizotto ◽  
J Riley Edwards ◽  
Arthur de Oliveira
Keyword(s):  
Fatigue Life ◽  
Design Principles ◽  
Lateral Load ◽  
System Component ◽  
Applied Loading ◽  
Component Design ◽  
Stress Reversals ◽  
Fatigue Failures ◽  
Empirical Design

To address a recent challenge related to broken spikes in premium elastic fastening systems that have led to at least ten derailments and require manual walking inspections as well as build upon mechanistic-empirical (M-E) design principles for future fastening system component design, this paper quantifies the vertical, lateral, and longitudinal fastening system loads under revenue service traffic in a curve that has regularly experienced spike fastener fatigue failures. Previous data has indicated that the high rail of Track 3 experienced the most failures at this location. The data from this investigation sheds light into why failures are more predominant at this location than others and how the vertical, lateral, and longitudinal loads cannot be considered independently. Specifically, while the magnitude of the applied loading was the lowest on the high rail of Track 3, the threshold for failure was also the lowest given the operations at this location led to unloading of the high rail, thus indirectly highlighting the importance of friction within a fastening system. The data also show the high rail of Track 3 was subjected to the highest L/V load ratios and was an outlier in the typical lateral load reversals applied likely leading to spike stress reversals and thus a shorter fatigue life. Finally, based upon the data, it is recommended that to mitigate spike failures, as well as similar fastener challenges in other track types (e.g. rail seat deterioration, etc.) railroads should ensure trains operate close to the balance speed and use fastening system that transfer loads through friction. This study also provides novel data for M-E design of fastening systems.

scholarly journals Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Jiang ◽  
Gun Jin Yun ◽  
Li Zhao ◽  
Junyong Tao
Keyword(s):  
Fatigue Life ◽  
Stress Responses ◽  
Life Prediction ◽  
Random Vibration ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Power Spectral ◽  
Vibration Fatigue ◽  
Non Gaussian

Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.

scholarly journals FATIGUE LIFE ANALYSIS OF RAMP DOOR FERRY RO-RO GT 1500 USING FINITE ELEMENT METHOD

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Alamsyah Alam ◽  
A. B. Mapangandro ◽  
Amalia Ika W ◽  
M U Pawara
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Structural Integrity ◽  
Load Cycle ◽  
Point Load ◽  
Fatigue Life Analysis ◽  
The Given ◽  
Element Method

Ro - Ro Ferry is equipped with a connecting door between the port and the ship. The ramp door experiences load during loading and discharging of the rolling cargo. This repetitive load may cause fatigue failure. The structure of the ramp door should withstand this load. Therefore, The ramp door should be properly designed to ensure the structural integrity of the ramp door. The purpose of this research is to analyze the maximum stress and the Fatigue life of the bow ramp door. The method used is the finite element method. The given loads are several types of vehicles that are commonly transported by the ship. The given load case is the point load working at the girder plate and between the girder plate. Based on the simulation results with the given point load, the maximum stress is identified located between the girder for the large truck case with 397.02 MPa, while the minimum stress located at the girder for sedan car with 43.93 MPa. As for the fatigue life of the bow ramp door construction. it is 1.17 ~ 398.64 years, and the load cycle is 5.35 x 104 ~ 9.05 x 106 cycle. Keywords : Bow Ramp Door; Stress; Fatigue Life; Finite Element; Ferry

Experimental Study on the Effect of Surface Integrity on Fatigue Performance of Aero-Engine Blades

2021 ◽  
Author(s):  
Yun Huang ◽  
Shaochuan Li ◽  
Guijian Xiao ◽  
Benqiang Chen ◽  
Yi He ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Test ◽  
Surface Texture ◽  
Surface Characteristics ◽  
Service Performance ◽  
Aero Engine ◽  
Vibration Fatigue

Abstract As the core component of aero-engine, the service performance of aero-engine blade has an important influence on the engine’s reliability and safety performance. Existing studies have shown that machined surface characteristics affect the fatigue strength of components. However, current studies are all based on regular fatigue samples. The structure of blades different from fatigue samples, and the influence mechanism of structural differences on the service performance of blades is still unclear. In addition, the conventional fatigue test conditions are not representative for the blades’ actual service conditions, so it is difficult to realize the processing process for the service performance optimization. In this study, the aero-engine blades processed by abrasive belt grinding and the vibration fatigue test bench were used to explore the influence of surface roughness, surface texture, and surface residual stress on the fatigue performance of aero-engine blades under actual working conditions. The aero-engine blades were ground with different process parameters to obtain different single-factor surface characteristics. By comparing the vibration fatigue life of blades with different surface features, the influence degree of each surface feature on the fatigue life was explored. Results showed that surface roughness has the greatest influence on fatigue strength, followed by residual stress, and surface texture has the least influence on fatigue strength.

Effects of Cryogenic Laser Peening on Damping Characteristics and Vibration Fatigue Life of TC6 Titanium Alloy

2020 ◽  
Vol 47 (4) ◽  
pp. 0402011
Author(s):  
黄宇 Huang Yu ◽  
周建忠 Zhou Jianzhong ◽  
李京 Li Jing ◽  
田绪亮 Tian Xuliang ◽  
孟宪凯 Meng Xiankai ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Laser Peening ◽  
Damping Characteristics ◽  
Vibration Fatigue

Structural integrity assessment for a component of the bucket-wheel excavator

2014 ◽  
Vol 5 (2) ◽  
pp. 129-140 ◽  
Author(s):  
Anghel Cernescu ◽  
Liviu Marsavina ◽  
Ion Dumitru
Keyword(s):  
Risk Factor ◽  
Fatigue Life ◽  
Crack Length ◽  
Structural Integrity ◽  
Evaluation Procedure ◽  
Content Type ◽  
Integrity Assessment ◽  
Material Component ◽  
High Level ◽  
Remaining Fatigue Life

Purpose – The purpose of this paper is to present a methodology for assessing the structural integrity of a tie member from a bucket-wheel excavator, ESRC 470 model, which was in operation for about 20 years. The tie member is made of S355J2N structural steel. Following the period of operation, the occurrence of microcracks which can propagate by fatigue is almost inevitable. It is therefore necessary to analyze the structural integrity and the remaining life of the component analyzed. Design/methodology/approach – In principle, the assessment methodology is based on three steps: first, the evaluation of mechanical properties of the material component; second, a BEM analysis using FRANC 3D software package to estimate the evolution of the stress intensity factor based on crack length and applied stress; third, risk factor estimation and remaining fatigue life predictions based on failure assessment diagram and fatigue damage tolerance concept. Findings – Following the evaluation procedure were made predictions of failure risk factor and remaining fatigue life function of crack length and variable stress range, for a high level of confidence. Originality/value – As results of this analysis was implemented a program for verification and inspection of the tie member for the loading state and development of small cracks during operation.

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