An Extrema Approach to Probabilistic Creep Modeling in Finite Element Analysis

2021 ◽  
Author(s):  
Md Abir Hossain ◽  
Jacqueline R Cottingham ◽  
Calvin M. Stewart
Keyword(s):  
Finite Element ◽  
Goodness Of Fit ◽  
Full Scale ◽  
Spatial Uncertainty ◽  
304 Stainless Steel ◽  
Computational Time ◽  
Extremum Condition ◽  
Wide Range ◽  
Extremum Conditions ◽  
2D Model

Abstract This paper introduces a computationally efficient extremum condition-based Reduced Order Modeling (ROM) approach for the probabilistic predictions of creep in finite element (FE). Component-level probabilistic simulations are needed to assess the reliability and safety of high-temperature components. Full-scale probabilistic creep models in FE are computationally expensive, requiring many hundreds of simulations to replicate the uncertainty of component failure. In this study, an extremum condition-based ROM approach is proposed. In the extremum approach, full-scale probabilistic simulations are completed in 1D across a wide range of stresses, the data is processed and extremum conditions extracted, and those conditions alone are applied in 2D/3D FE to predict the mean and range of creep-failure. The probabilistic Sinh model, calibrated for alloy 304 stainless steel, is selected . The uncertainty sources (i.e. test condition, pre-existing damage, and model constants) are evaluated and pdfs sampling are performed via Monte carlo method. The extremum conditions are chosen from numerous 1D model simulations. These conditions include extremum cases of creep ductility, rupture, and area under creep curves. Only the extremum cases are simulated for 2D model saving significant computational time and memory. The goodness-of-fit of the predicted creep response for 1D and 2D model shows satisfactory agreement with the experimental data. The accuracy of the extremum condition-based ROM will reduce significant computational burden of simulating complex engineering systems. Introduction of multi-stage Sinh, stochasticity, and spatial uncertainty will further improve the prediction.

scholarly journals A Reduced Order Modeling Approach to Probabilistic Creep-Damage Predictions in Finite Element Analysis

2021 ◽  
Author(s):  
Md Abir Hossain ◽  
Jacqueline R. Cottingham ◽  
Calvin M. Stewart
Keyword(s):  
Finite Element ◽  
Computational Cost ◽  
Creep Damage ◽  
Reduced Order Modeling ◽  
Full Scale ◽  
Spatial Uncertainty ◽  
304 Stainless Steel ◽  
Probabilistic Prediction ◽  
Reduced Order ◽  
Finite Element Software

Abstract This paper introduces a computationally efficient Reduced Order Modeling (ROM) approach for the probabilistic prediction of creep-damage failure. Component-level probabilistic simulations are needed to assess the reliability and safety of high-temperature components. Full-scale probabilistic creep-damage modeling in finite element (FE) approach is computationally expensive requiring many hundreds of simulations to replicate the uncertainty of component failure. To that end, ROM is proposed to minimize the elevated computational cost while controlling the loss of accuracy. It is proposed that full-scale probabilistic simulations can be completed in 1D at a reduced cost, the extremum conditions extracted, and those conditions applied for lower cost 2D/3D probabilistic simulations of components that capture the mean and uncertainty of failure. The probabilistic Sine-hyperbolic (Sinh) model is selected which in previous work was calibrated to alloy 304 stainless steel. The Sinh model includes probability density functions (pdfs) for test condition (stress and temperature), initial damage (i.e., microstructure), and material properties uncertainty. The Sinh model is programmed into ANSYS finite element software using the USERCREEP.F material subroutine. First, the Sinh model and FE code are subject to verification and validation to affirm the accuracy of the simulations. Numerous Monte Carlo simulations are executed in a 1D model to generate probabilistic creep deformation, damage, and rupture data. This data is analyzed and the probabilistic parameters corresponding to extreme creep response are extracted. The ROM concept is applied where only the extreme conditions are applied in the 2D probabilistic prediction of a component. The probabilistic predictions between the 1D and 2D model is compared to assess ROM for creep. The accuracy of the probabilistic prediction employing the ROM approach will potentially reduce the time and cost of simulating complex engineering systems. Future studies will introduce multi-stage Sinh, stochasticity, and spatial uncertainty for improved prediction.

Efficient Prediction of Contact Behavior in a 6-High Rolling Mill With Continuously Variable Crown Intermediate Rolls

2017 ◽  
Author(s):  
Feng Zhang ◽  
Arif S. Malik
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Mixed Finite Element ◽  
Mixed Finite Element Method ◽  
High Strength ◽  
Computational Time ◽  
Ferrous Alloys ◽  
Thickness Profile ◽  
Wide Range ◽  
Contact Force Distribution

Continuously Variable Crown (CVC) shifting mechanisms represent a control technology with wide range of capability to influence the thickness profile and flatness (shape) of metal strip and sheet in rolling-type manufacturing processes. Further, because of the efficiency and extensive control capability to operate on thin-gauge, high-strength ferrous alloys, the 6-high mill with CVC profiles machined onto the intermediate rolls (IR) represents a popular mill configuration. This is because of the large control range for the strip thickness profile and flatness, which results from lateral shifting of the CVC intermediate rolls. However, together with this efficiency and capability comes very complex contact behaviors between the rolls and strip, including highly non-linear contact force distribution, loss of contact, asymmetric roll wear, unwanted strip wedge profiles, and the need to apply corrective roll tilting. Therefore, for most effective industry use of 6-high mills with intermediate roll CVC shifting, a rapid and accurate mathematical rolling model is needed to predict and account for these complex contact behaviors. This paper introduces an efficient roll-stack computational model capable of simulating such rolling mills under steady-state conditions. The model formulation applies the simplified mixed finite element method (SM-FEM), which is adapted to simulate asymmetric 6-high CVC mill contact behaviors. Results for a specific case study compare favorably to those obtained from a large-scale commercial finite element simulation, yet require a small fraction of the associated computational time and effort.

scholarly journals Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6794
Author(s):  
Zhou Yan ◽  
Hany Hassanin ◽  
Mahmoud Ahmed El-Sayed ◽  
Hossam Mohamed Eldessouky ◽  
Joy Rizki Pangestu Djuansjah ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Processing Time ◽  
Incremental Forming ◽  
Single Point ◽  
Computational Time ◽  
Single Point Incremental Forming ◽  
Two Stage ◽  
Element Analysis ◽  
Wide Range

Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.

scholarly journals Efficient exascale discretizations: High-order finite element methods

2021 ◽  
pp. 109434202110208
Author(s):  
Tzanio Kolev ◽  
Paul Fischer ◽  
Misun Min ◽  
Jack Dongarra ◽  
Jed Brown ◽  
...  
Keyword(s):  
Finite Element ◽  
Research And Development ◽  
Finite Element Methods ◽  
Large Scale ◽  
High Efficiency ◽  
High Order ◽  
Computational Time ◽  
Data Movement ◽  
Wide Range ◽  
Matrix Free

Efficient exploitation of exascale architectures requires rethinking of the numerical algorithms used in many large-scale applications. These architectures favor algorithms that expose ultra fine-grain parallelism and maximize the ratio of floating point operations to energy intensive data movement. One of the few viable approaches to achieve high efficiency in the area of PDE discretizations on unstructured grids is to use matrix-free/partially assembled high-order finite element methods, since these methods can increase the accuracy and/or lower the computational time due to reduced data motion. In this paper we provide an overview of the research and development activities in the Center for Efficient Exascale Discretizations (CEED), a co-design center in the Exascale Computing Project that is focused on the development of next-generation discretization software and algorithms to enable a wide range of finite element applications to run efficiently on future hardware. CEED is a research partnership involving more than 30 computational scientists from two US national labs and five universities, including members of the Nek5000, MFEM, MAGMA and PETSc projects. We discuss the CEED co-design activities based on targeted benchmarks, miniapps and discretization libraries and our work on performance optimizations for large-scale GPU architectures. We also provide a broad overview of research and development activities in areas such as unstructured adaptive mesh refinement algorithms, matrix-free linear solvers, high-order data visualization, and list examples of collaborations with several ECP and external applications.

Effect of strut length and orientation on elastic mechanical response of modified body-centered cubic lattice structures

2019 ◽  
Vol 233 (11) ◽  
pp. 2219-2233 ◽  
Author(s):  
Hasanain S Abdulhadi ◽  
Ahsan Mian
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Reference Model ◽  
Computational Time ◽  
Lattice Structures ◽  
Body Centered Cubic ◽  
Angle Variation ◽  
Fused Deposition ◽  
Finite Element Software ◽  
Wide Range

Lattice structures (LSs) have been exploited for wide range of applications including mechanical, thermal, and biomedical structures because of their unique attributes combining the light weight and high strength. The main goal of this research is to investigate the effect of strut length and orientation on the mechanical characteristics of modified body-centered cubic (BCC) LS subjected to a quasi-static axial compressive loading within linear elastic limit using finite element analysis. In this study, two sets of LS were built and analyzed in commercial finite element software, ABAQUS/CAE/EXPLICIT 6.16, using a “smart procedure,” which was developed for this research to reduce the computational time and increase the accuracy of results by creating hexahedral mesh elements. The first set comprises 13 models having fixed strut length with strut angle variation from 40° to 100° with a step of 5°. The second set also includes 13 models; however, having variant strut length, kept constant for a single unit cell and through the entire model but varied from one model to another, with the same strut angle variation as the first set. In addition, the BCC LS with a strut angle of 70.53° was replicated in both sets because it was considered as a reference model to compare the results with it. Furthermore, specimens of the reference model were fabricated by a fused deposition modeling- (FDM) based 3D printer using acrylonitrile butadiene styrene (ABS) material and tested experimentally under compression. Experimental results are observed to be in good agreement with those of the finite element simulation, hence the same loading and boundary conditions were adopted for all other models. It was observed that the fixed strut length BCC LS with a strut angle of 100° offers the highest modulus. However, the highest specific strain energy absorption and specific stiffness as well as the least value of weight were dictated by a variant strut length BCC LS with a strut angle of 40°.

An Experimental and Finite Element Study of the Ductile Tearing Characteristics of High-Toughness Gas Pipeline Steel

2006 ◽  
Vol 3-4 ◽  
pp. 259-266 ◽  
Author(s):  
S.S. Ayvar ◽  
S.H. Hashemi ◽  
I.C. Howard ◽  
J.R. Yates
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Pipeline Steel ◽  
Shape Change ◽  
Gas Pipeline ◽  
Computational Time ◽  
Damage Development ◽  
Element Analysis ◽  
Crack Growth Behaviour ◽  
2D Model

This paper reports recent results from a set of experimental and computational studies of ductile flat fracture in modern gas pipeline steel. Experimental data from plain and notched cylindrical tensile bars and standard C(T) specimens together with damage mechanics theories have been used to capture the flat fracture characteristics of a gas pipeline steel of grade X100. The modelling was via finite element analysis using the Gurson-Tvergaard modified model (GTN) of ductile damage development. The assumption of effective material damage isotropy was sufficiently accurate to allow the transfer of data from the notched bars to predict, in a 2D model, the crack growth behaviour of the C(T) specimen. This was in spite of the considerable ovalisation of the bars at the end of their deformation. However, it was not possible to obtain similar accuracy with a 3D model of the C(T)test, even after a large number of attempts to adjust the values of the GTN parameters. This, and the anisotropic shape change in the tensile bars, suggests very strongly that the damage behaviour is so anisotropic that conventional models are not good enough for a full engineering description of the flat fracture behaviour. Suitable averaging (of shape) in the modelling of the notched bar data, and the companion averaging associated with the 2D model of the C(T) data provide a relatively fast way of transferring engineering data in the tests. There is a discussion of potential ways in which to incorporate 3D effects into the modelling for those purposes where the considerable increase in computational time (due to the microstructurally-sized finite elements needed to capture the damage behaviour) is acceptable in order to include through-thickness effects.

scholarly journals Finite element simulation and regression modeling of machining attributes on turning AISI 304 stainless steel

2021 ◽  
Vol 8 ◽  
pp. 24
Author(s):  
A. Mathivanan ◽  
M.P. Sudeshkumar ◽  
R. Ramadoss ◽  
Chakaravarthy Ezilarasan ◽  
Ganesamoorthy Raju ◽  
...  
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cutting Force ◽  
Cutting Speed ◽  
304 Stainless Steel ◽  
Computational Time ◽  
Depth Of Cut ◽  
Aisi 304 Stainless Steel ◽  
Machining Processes ◽  
Aisi 304

To-date, the usage of finite element analysis (FEA) in the area of machining operations has demonstrated to be efficient to investigate the machining processes. The simulated results have been used by tool makers and researchers to optimize the process parameters. As a 3D simulation normally would require more computational time, 2D simulations have been popular choices. In the present article, a Finite Element Model (FEM) using DEFORM 3D is presented, which was used to predict the cutting force, temperature at the insert edge, effective stress during turning of AISI 304 stainless steel. The simulated results were compared with the experimental results. The shear friction factor of 0.6 was found to be best, with strong agreement between the simulated and experimental values. As the cutting speed increased from 125 m/min to 200 m/min, a maximum value of 750 MPa stress as well as a temperature generation of 650 °C at the insert edge have been observed at rather higher feed rate and perhaps a mid level of depth of cut. Furthermore, the Response Surface Methodology (RSM) model is developed to predict the cutting force and temperature at the insert edge.

Development and Testing of Structurally Independent Foundations for High-Speed Containment Concrete Barrier

2021 ◽  
pp. 036119812098032
Author(s):  
James Kovar ◽  
Nauman Sheikh ◽  
Roger Bligh ◽  
Sofokli Cakalli ◽  
Taya Retterer ◽  
...  
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Full Scale ◽  
Drilled Shaft ◽  
Site Conditions ◽  
Critical Systems ◽  
Crash Testing ◽  
Wide Range ◽  
Slab Foundation ◽  
Test Level

This paper presents the development and testing of single slope barriers with independent foundations that can be installed at a wide range of site conditions. The researchers developed designs of barriers with foundation systems by conducting a series of finite element simulations and performing full-scale vehicle impact tests under the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware ( MASH) Test Level 5 (TL-5) and Test Level 4 (TL-4) conditions. In this process, foundation designs were developed for site conditions that may require shallow foundations, or foundations that have a smaller footprint. Depending on the site conditions and the presence of underground structures, designers could select the most fitting option from these designs. Impact performance of the developed barrier and foundation systems was evaluated using full-scale finite element impact simulations under MASH TL-5 and TL-4 impact conditions. Two critical systems were selected for full-scale crash testing: a 54 in. tall single slope barrier with drilled shaft foundations, and a 36 in. tall single slope barrier with moment slab foundation. The barrier with the drilled shaft foundation system was tested to MASH Test 5-12 conditions, and the barrier with the moment slab foundation system was tested to MASH Test 4-12 conditions. Both systems performed acceptably with respect to the MASH criteria. This paper presents the various barrier and foundation designs that were developed, key results from the simulation analyses, and details of the crash testing performed on the two selected systems.

Design of Pipeline Composite Repairs: From Lab Scale Tests to FEA and Full Scale Testing

2014 ◽  
Author(s):  
Remy Her ◽  
Jacques Renard ◽  
Vincent Gaffard ◽  
Yves Favry ◽  
Paul Wiet
Keyword(s):  
Finite Element ◽  
Full Scale ◽  
Combined Loading ◽  
Material Strength ◽  
Repair System ◽  
Loading Conditions ◽  
Original Design ◽  
Composite Repair ◽  
Repair Systems ◽  
Composite Properties

Composite repair systems are used for many years to restore locally the pipe strength where it has been affected by damage such as wall thickness reduction due to corrosion, dent, lamination or cracks. Composite repair systems are commonly qualified, designed and installed according to ASME PCC2 code or ISO 24817 standard requirements. In both of these codes, the Maximum Allowable Working Pressure (MAWP) of the damaged section must be determined to design the composite repair. To do so, codes such as ASME B31G for example for corrosion, are used. The composite repair systems is designed to “bridge the gap” between the MAWP of the damaged pipe and the original design pressure. The main weakness of available approaches is their applicability to combined loading conditions and various types of defects. The objective of this work is to set-up a “universal” methodology to design the composite repair by finite element calculations with directly taking into consideration the loading conditions and the influence of the defect on pipe strength (whatever its geometry and type). First a program of mechanical tests is defined to allow determining all the composite properties necessary to run the finite elements calculations. It consists in compression and tensile tests in various directions to account for the composite anisotropy and of Arcan tests to determine steel to composite interface behaviors in tension and shear. In parallel, a full scale burst test is performed on a repaired pipe section where a local wall thinning is previously machined. For this test, the composite repair was designed according to ISO 24817. Then, a finite element model integrating damaged pipe and composite repair system is built. It allowed simulating the test, comparing the results with experiments and validating damage models implemented to capture the various possible types of failures. In addition, sensitivity analysis considering composite properties variations evidenced by experiments are run. The composite behavior considered in this study is not time dependent. No degradation of the composite material strength due to ageing is taking into account. The roadmap for the next steps of this work is to clearly identify the ageing mechanisms, to perform tests in relevant conditions and to introduce ageing effects in the design process (and in particular in the composite constitutive laws).

The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

2021 ◽  
pp. 107754632199759
Author(s):  
Jianchun Yao ◽  
Mohammad Fard ◽  
John L Davy ◽  
Kazuhito Kato
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Dynamic Performance ◽  
Complex Structure ◽  
Vehicle Body ◽  
Computational Time ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Transfer Matrices ◽  
Body Vibration

Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predict the dynamic performance of the complex structure. The numerical transfer matrices can also be the subject of machine learning for various applications such as for the prediction of the vibration discomfort of the occupant with different seat and foam designs and with different physical characteristics of the occupant body.

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