Numerical fatigue assessment of welded and HFMI-treated joints by notch stress/strain and fracture mechanical approaches

Leitner, Martin; Šimůnek, David; Shah, Syed Faheem; Stoschka, Michael

doi:10.1016/j.advengsoft.2016.01.022

Cited by 30 publications

(36 citation statements)

References 33 publications

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“…Engineering knowledge dictates that the above two factors would be crucial for the final residual stress (RS) state of the component, and based on the present state of the art Sum of squared estimate of errors (-) RMSE Root-mean-square error (-) both of them can be considered in a FE analysis. This was validated in two recent studies (Ref 18,19), which have shown that the consideration of WRS and viscous material behavior can significantly increase the accuracy of HFMI simulation. Besides, simulation of the WRS has evolved rapidly in the last decades and most of the practical and special aspects of the method regarding metal arc welding have been covered in previous studies of the authors (Ref [20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 57%

Calibration of High-Frequency Mechanical Impact Simulation Based on Drop Tests

Gkatzogiannis

Knoedel

Ummenhofer

2020

J. of Materi Eng and Perform

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A series of drop tests was implemented in the present study in order to allow the reproduction of a single impact identical to the high frequency mechanical impact (HFMI) under monitored conditions in the laboratory. Therewith, characterization of the investigated materialÕs mechanical behavior by explicitly considering possible irregularities concerning the present deformation modes would be enabled. Main goal was the determination of the investigated materialÕs dynamic yield stress for various strain rates inside the spectrum of interest, so that the Cowper-Symonds viscous material model would be calibrated for the subsequent HFMI simulation. The values of the dynamic yield stress extracted by the present drop tests show good agreement with other experimental methods regarding the investigated material S355. The introduction of the calibrated material behavior on the present drop tests in the finite element (FE) analysis of HFMI led to reduced preciseness though, in comparison with the FE analysis, which considered high strain rate tensile tests found in literature. A series of conclusions was drawn from both the experimental and numerical investigations, confirming most of the initial expectations. Further work is proposed, in order to clarify an incompatibility met during the numerical investigations. Keywords FE analysis, high frequency mechanical impact, residual stresses, simulation, strain rate dependency This article is an invited submission to JMEP selected from presentations at the Symposium ''Joining and Related Technologies,'' belonging to the topic ''Processing'' at the European Congress and Exhibition on Advanced Materials and Processes (EUROMAT 2019), held September 1-5, 2019, in Stockholm, Sweden, and has been expanded from the original presentation.

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Section: Introductionmentioning

confidence: 57%

Calibration of High-Frequency Mechanical Impact Simulation Based on Drop Tests

Gkatzogiannis

Knoedel

Ummenhofer

2020

J. of Materi Eng and Perform

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“…Thereby, the weld simulation is modeled in accordance to the real weld procedure including three single-sided weld passes; see left subfigure in Figure 3. Details to the applied material data, boundary conditions, as well as weld process parameters are provided in [30,47]. After structural weld simulation, the final specimen geometry is numerically cut-out of the weld array by eliminating the remaining elements in the model and the local residual stress state in the mid area of the sample, where the gas pores are located, is analyzed.…”

Section: Hardness and Residual Stress Conditionmentioning

confidence: 99%

“…This comparably minor residual stress state can be explained by the single-sided three-pass weld procedure, which is significantly different to the double-sided two-pass welding in case of the test series √area < 1000 µm, leading to a local tempering of the central weld seam region due to the last weld pass at the top. In order to consider the local effective stress ratio R eff , the local residual stress value σ res in axial direction within the volume of the imperfections is evaluated by means of X-ray diffraction [46] for test series √ area < 1000 µm, and structural weld simulation [47] for test series √ area > 1000 µm. Within the X-ray measurements, the residual stresses are evaluated based on CrKα radiation using the d(sin2Ψ) cross-correlation method, a collimator size of 1 mm, a duration of exposure of 20 s, and a Young's modulus of 2.1 GPa.…”

Section: Hardness and Residual Stress Conditionmentioning

confidence: 99%

Fatigue Strength Assessment of Welded Mild Steel Joints Containing Bulk Imperfections

Leitner

Murakami

Farajian

et al. 2018

Metals

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This work investigates the effect of gas pores, as bulk imperfections, on the fatigue strength of welded mild steel joints. Two test series containing different butt joint geometries and weld process parameters are included in order to achieve two variable types of pore sizes. Based on the √ area-parameter by Murakami, the test series can be grouped into imperfections exhibiting √ area < 1000 µm and √ area > 1000 µm. Fatigue tests at a load stress ratio of R = 0.1 are performed, which act as comparison for the subsequent fatigue estimation. To assess the fatigue resistance, the approaches by Murakami, De Kazinczy, and Mitchell are utilized, which highlight certain differences in the applicability depending on the imperfection size. It is found that, on one hand, Murakami's approach is well suitable for both small and large gas pores depending on the applied model parameters. On the other hand, the fatigue concepts by De Kazinczy and Mitchell are preferably practicable for large defects with √ area > 1000 µm. In addition, the method by Mitchell incorporates the stress concentration factor of the imperfection, which can be numerically computed considering the size, shape, and location of the gas pore, as presented in this paper.

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“…Its vital function is to convert the tensile residual stress to compressive residual stress to extend the fatigue life of the fused component [16]. The efficiency of HFMI technology to increase the fatigue life of bonded steel were broadly discussed by many researchers [15], [17] - [22]. Life Enhancement of Transverse Fillet Weld on Welds of HSLA S460G2+M using HFMI/PIT HFMI/PIT is the latest HFMI technology that invented with consistence mechanical impact on the treated region and eventually exceptional effect for fatigue life enhancement, especially for high strength steel [19]- [21].…”

Section: Introductionmentioning

confidence: 99%

Life Enhancement of Transverse Fillet Weld on Welds of HSLA S460G2+M using HFMI/PIT

Andud¹,

Kamal²,

Manurung³

et al. 2019

IJEAT

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 Abstract: This study deals with the fatigue life enhancement of the transverse fillet weld on welds of 10mm thickness of the high strength low alloy steel (HSLA) S460G2+M which is treated using high frequency mechanical impact tool called pneumatic impact treatment (HFMI/PIT). Initially, the plate S460g2+M is prepared with groove angles of butt joint and joined using gas metal arc welding (GMAW) with multi-pass welds followed by to weld the transverse attachment over the existing welds to produce a fillet weld on welds. Secondly, the HFMI/PIT treatment is applied on the fillet weld toe using 90Hz frequency, 6 bars of pneumatic pressure and 2 mm pin radius. Thirdly, the fatigue tests with constant amplitude loading are conducted on the untreated and treated specimens by applying 0.1 stress ratio and 55% to 75% stress loading from the yield strength of the base material. All fatigue data were evaluated based on international welding institute (IIW) commission XIII. It is found that the fatigue life of treated specimen is higher as compared with the untreated specimen. However, it is observed that an excessive heat input due to multi-pass welds has insignificant effect to the fatigue life of the untreated specimen. Index Terms: Transverse Fillet weld on welds, HFMI/PIT, FAT class, S460G2 + M.

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Numerical fatigue assessment of welded and HFMI-treated joints by notch stress/strain and fracture mechanical approaches

Cited by 30 publications

References 33 publications

Calibration of High-Frequency Mechanical Impact Simulation Based on Drop Tests

Calibration of High-Frequency Mechanical Impact Simulation Based on Drop Tests

Fatigue Strength Assessment of Welded Mild Steel Joints Containing Bulk Imperfections

Life Enhancement of Transverse Fillet Weld on Welds of HSLA S460G2+M using HFMI/PIT

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