Fatigue Strength Assessment of Steel Rollers: On the Reliability of the Strain Energy Density Approach on Real Components

Chebat, Francesco; Peron, Mirco; Viespoli, Luigi Mario; Welo, Torgeir; Berto, Filippo

doi:10.3390/app8071015

Cited by 16 publications

(13 citation statements)

References 41 publications

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“…Yet, this is highly relevant in the field of complex geometric design as such attempts naturally introduce such discontinuities reported to strongly affect both tensile and fatigue properties of the components [16][17][18][19][20][21][22][23][24][25][26]. In fatigue, the effect of notches is unambiguous, determining a reduction in the fatigue strength for several materials [27][28][29][30][31][32][33][34]. Concerning tensile strength, instead, notched specimens have been reported to be characterized either by a notch strengthening or by a notch weakening behaviour [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Fracture behaviour of notched as-built EBM parts: Characterization and interplay between defects and notch strengthening behaviour

Peron

Torgersen

Ferro

et al. 2018

Theoretical and Applied Fracture Mechanics

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Additive manufacturing (AM) offers the potential to economically produce customized components with complex geometries. However, the introduction of complex geometry goes hand in hand with the presence of notches. Thus, the basic understanding of the tensile behaviour of AM fabricated notched components must be substantially improved so that the unique features of this rapidly developing technology can be utilized in critical load bearing applications. This work aims to assess the tensile behaviour of different notched specimens manufactured by means of the Electron Beam Melting (EBM) technology and tested in their as-built conditions in order to reveal the interplay between notch geometry and AM specific processing. Scanning Electron Microscopy (SEM) was used to investigate the fracture surface of the broken samples, revealing the presence of process-induced defects, harmfully affecting tensile strength with a reduction of 10% and elongation to failure with 40% with respect to values reported in literature for heat treated AM parts, respectively. Interestingly, the authors have discovered an increase in the tensile strength with the severity of the stress concentrators, quite contrary to what is commonly observed for wrought Ti-6Al-4V. This notch strengthening behaviour particular to AM specimens is related to the influence of defects on the failure driving force. The authors provide a qualitative explanation for this phenomenon using 3D FE analyses together with a theoretical description via the ellipse criterion.

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Section: Introductionmentioning

confidence: 99%

Fracture behaviour of notched as-built EBM parts: Characterization and interplay between defects and notch strengthening behaviour

Peron

Torgersen

Ferro

et al. 2018

Theoretical and Applied Fracture Mechanics

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“…Moreover, the strain energy range can either be obtained analytically, deriving the stress fields ahead of the geometrical discontinuity, or by means of FE analyses with a coarse mesh, being mesh-insensitive [35,36]. This tool has been widely reported to accurately predict the tensile and fatigue behavior of different notched materials [37][38][39][40][41] and for real component such as steel rollers [42], and its improvements with respect of the TCD methodologies has been reported in details in [43] for Ti-6Al-4V. In addition, it has recently been utilized to predict the fracture and fatigue behavior of plastics [44][45][46], including the biocompatible biopolymer polyetheretherketone (PEEK) [47,48].…”

Section: Introductionmentioning

confidence: 99%

Assessment of tensile and fatigue behavior of PEEK in a physiologically relevant environment

Peron¹,

Torgersen²,

Berto³

2018

Frattura Ed Integrità Strutturale

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In the last decades the necessity of implant devices is continuously increasing. The researchers have thus focused their attentions on the development of new biocompatible materials, in particular polymers. Among them, polyetheretherketone (PEEK) has gained wide interest in loadbearing applications such as spinal cages due to its yielding behavior and its superior corrosion resistance. Since such applications are characterized by notches and other stress concentrators weakening the implant resistance, a design tool for assessing their tensile and fatigue behavior, in the presence of such discontinuities, is highly claimed. To this aim, tensile and fatigue data available in literature related to neat and differently notched PEEK samples, experimentally tested in a phosphate-buffered saline (PBS) at 37 °C have been analyzed using the strain energy density (SED) approach. The method is shown to provide accurate results regardless of the different notch geometries, both in terms of tensile and fatigue behavior. Concerning the former, the tensile strength was in fact estimated with an error lower than ±10%, whereas for the latter the SED approach was able to summarize the experimental fatigue data in a single narrow scatter band, independently from the notch geometry.

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“…ALT can take the form of "Acceleration of the rate of use" or "Overload and acceleration". The ALT methods due to the acceleration of the usage rate and the test data can be analyzed with typical life data and methods of analysis, the acceleration of excessive stresses [32,[34][35][36][37][38].…”

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confidence: 99%

“…The purpose of the known components and the reliability of the systems is a fundamental issue. The reliability assessment is normally based on the collection of field data during the daily work of the assets [34][35][36][37]. If the data collection is not automated, it is a laborious activity due to a very long period required.…”

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Reliable Method to Detect Alloy Soldering Fractures under Accelerated Life Test

et al. 2019

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In this research, we investigated the development and design of the Accelerated Life Test (ALT) and its approach to the waste of material. The development of a reliability model is based on the moment at which failure appears. The faults detected in welding joints during this research prevented proper current flow within electronic components and this interruption of current is considered a critical system failure. Minitab v18 was used to process data. Through statistical analysis, it was determined that the sample size was adequate with a 95% level of significance. A Shapiro Wilk analysis was carried out to determine the normality of the data, where a p-value of 0.1349 was obtained, which indicates that the data are normal. A Weibull analysis was applied, and it was observed that the data adjusted to the regression analysis and Weibull’s reliability distribution. The results showed that failure phenomena can occur during electronic assembly due to the values of R being too high and too close to each other. Significant issues included the welding alloy, temperature, and the interaction between the welding alloy and vibration. It is observed that with high temperature, the number of faults in the solder alloy used for tin and lead and for tin, silver, and copper were lower. 17 electronic assemblies with measures of 2 cm × 2 cm were fabricated, where components such as leads and electric resistance were used. The objective of analyzing this is to obtain the characteristics of the soldering alloy. Electronic components of this type are used worldwide in all types of electronic components, including: TVs, cell phones, tablet, computers, resistors, diodes, LEDs, and capacitors. For this work, the components were built based on an LED and a diode.

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Fatigue Strength Assessment of Steel Rollers: On the Reliability of the Strain Energy Density Approach on Real Components

Cited by 16 publications

References 41 publications

Fracture behaviour of notched as-built EBM parts: Characterization and interplay between defects and notch strengthening behaviour

Fracture behaviour of notched as-built EBM parts: Characterization and interplay between defects and notch strengthening behaviour

Assessment of tensile and fatigue behavior of PEEK in a physiologically relevant environment

Reliable Method to Detect Alloy Soldering Fractures under Accelerated Life Test

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