Experimental Program for Investigating the Influence of Cladding Defects on Burst Pressure

2006 ◽  
Author(s):  
Shengjun (Sean) Yin ◽  
B. Richard Bass ◽  
Wallace J. McAfee ◽  
Paul T. Williams
Keyword(s):  
Finite Element ◽  
National Laboratory ◽  
Maximum Load ◽  
Plastic Instability ◽  
Experimental Program ◽  
Finite Element Models ◽  
Ductile Tearing ◽  
Oak Ridge ◽  
Clad Layer ◽  
Good Agreement

An experimental program was conducted by the Heavy-Section Steel Technology Program at the Oak Ridge National Laboratory (ORNL) to evaluate the structural significance of defects found in the unbacked cladding of the Davis-Besse vessel head. ORNL conducted total 13 clad burst tests with unflawed/flawed specimens. Failure pressure data from those tests indicated a high degree of repeatability for the tests performed in the clad burst program. Unflawed clad burst specimens failed around the full perimeter of the disk from plastic instability; an analytical model for plastic collapse was shown to adequately predict those results. The flawed specimens tested in the program failed by ductile tearing of the notch defect through the clad layer. Analytical interpretations that utilized 3-D finite element models of the clad burst specimens were performed for all tests. Fractographic studies were performed on failed defects in the flawed burst specimens to verify the ductile mode of failure. Comparisons of computed results from 3-D finite element models with measured gage displacement data (i.e., center-point deflection and CMOD) indicated reasonably good agreement up to the region of instability. For tests instrumented with the CMOD gage, good agreement between calculated and measured CMOD data up to the onset of instability implies that ductile tearing initiated near the maximum load and (with a small increase in load) rapidly progressed through the clad layer to produce failure of the specimen.

scholarly journals Mechanics of Tubes Composed of Interlocking Building Blocks

2022 ◽  
Author(s):  
Kyle Mahoney ◽  
Thomas Siegmund
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Transfer ◽  
Building Blocks ◽  
Maximum Load ◽  
Finite Element Models ◽  
Element Analysis ◽  
Internal Load ◽  
Deformation Response ◽  
Good Agreement

Topologically interlocking material (TIM) systems are composed of convex polyhedral units placed such that building blocks restrict each other's movement. Here, TIM tubes are considered as rolled monolayers of such assemblies. The deformation response of these assembled tubes under diametrical loading is considered. This investigation employs experiments on additivelymanufactured physical realizations and finite element analysis with contact interactions. The internal load transfer in topologically interlocking tubes is rationalized through inspection of the distribution of minimum principalstress. A thrust-line (TL) model for the deformation of topologically interlocking tubes is established. The model approximates the deformation response of the assembled tubes as the response of a collection of Misestrusses aligned with paths of maximum load transfer in the system. The predictions obtained with the TL-model are in good agreement with results of finite element models. Accounting for sliding between building blocks in theTL-model yields a predicted response more similar to experimental results with additively manufactured tubes.

ORNL Evaluation of Safety Cases for Two Belgian Reactor Pressure Vessels Containing Quasi-Laminar Defects

2017 ◽  
Author(s):  
Hilda B. Klasky ◽  
B. Richard Bass ◽  
Terry L. Dickson ◽  
Sarma B. Gorti ◽  
Randy K. Nanstad ◽  
...  
Keyword(s):  
New York ◽  
Finite Element ◽  
Structural Integrity ◽  
National Laboratory ◽  
Relevant Literature ◽  
Pressure Vessels ◽  
Oak Ridge ◽  
Safety Margins ◽  
Safety Cases ◽  
Reactor Pressure

The Oak Ridge National Laboratory (ORNL) performed a detailed technical review of the 2015 Electrabel (EBL) Safety Cases prepared for the Belgium reactor pressure vessels (RPVs) at Doel 3 and Tihange 2 (D3/T2). The Federal Agency for Nuclear Control (FANC) in Belgium commissioned ORNL to provide a thorough assessment of the existing safety margins against cracking of the RPVs due to the presence of almost laminar flaws found in each RPV. Initial efforts focused on surveying relevant literature that provided necessary background knowledge on the issues related to the quasi-laminar flaws observed in D3/T2 reactors. Next, ORNL proceeded to develop an independent quantitative assessment of the entire flaw population in the two Belgian reactors according to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section XI, Appendix G, “Fracture Toughness Criteria for Protection Against Failure,” New York (both 1992 and 2004 versions). That screening assessment of the EBL-characterized flaws in D3/T2 used ORNL tools, methodologies, and the ASME Code Case N-848, “Alternative Characterization Rules for Quasi-Laminar Flaws”. Results and conclusions derived from comparisons of the ORNL flaw acceptance assessments of D3/T2 with those from the 2015 EBL Safety Cases are presented in the paper. The ORNL screening analyses identified fewer flaws than EBL that were not compliant with the ASME Section XI (1992) criterion; the EBL criterion imposed additional conservatisms not included in ASME Section XI. Furthermore, ORNL’s application of the updated ASME Section XI (2004) criterion produced only four non-compliant flaws, all due to design-basis loss-of-coolant loading transients. Among the latter, only one flaw remained non-compliant when analyzed using the warm-prestress (WPS) cleavage fracture model typically applied in USA flaw assessments. ORNL’s independent refined analysis of that flaw (#1660, which was also non-compliant in the EBL screening assessments) rendered it compliant when modeled as a more realistic individual quasi-laminar flaw using a 3-dimensional XFEM (eXtended Finite Element Method) approach available in the ABAQUS© finite element code. Taken as a whole, the ORNL-specific results and conclusions confirmed the structural integrity of Doel 3 and Tihange 2 under all design transients with ample margin in the presence of the 16,196 detected flaws.

Contribution of Gear Body to Tooth Deflections—A New Bidimensional Analytical Formula

2004 ◽  
Vol 126 (4) ◽  
pp. 748-752 ◽  
Author(s):  
P. Sainsot and ◽  
P. Velex ◽  
O. Duverger
Keyword(s):  
Finite Element ◽  
Analytical Formula ◽  
Constant Stress ◽  
Finite Element Models ◽  
Gear Dynamics ◽  
Computer Codes ◽  
Stress Variations ◽  
Tooth Pair ◽  
Good Agreement

The magnitude and variation of tooth pair compliance affects tooth loading and gear dynamics significantly. This paper presents an improved fillet/foundation compliance analysis based on the theory of Muskhelishvili applied to circular elastic rings. Assuming linear and constant stress variations at root circle, the above theory makes it possible to derive an analytical formula for gear body-induced tooth deflections which can be directly integrated into gear computer codes. The corresponding results are in very good agreement with those from finite element models and the formula is proved to be superior to Weber’s widely used equation, especially for large gears.

Finite Element Modeling of Ductile Tearing of Pipeline-Steel in Cracked Plates

2004 ◽  
Author(s):  
Yu Chen ◽  
Steve Lambert
Keyword(s):  
Finite Element ◽  
Void Nucleation ◽  
Pipeline Steel ◽  
Damage Model ◽  
Tensile Load ◽  
Maximum Load ◽  
Void Coalescence ◽  
Ductile Tearing ◽  
Numerical Predictions ◽  
Measured Load

The purpose of this work was to develop a three-dimensional finite element model to simulate ductile tearing in pipeline-steels. The measured load versus displacement histories for single edge notch tension (SENT) and surfaced-cracked wide plate specimens, both made of X-70 pipeline-steel plates and subject to tensile load, were numerically predicted using the proposed damage model. In the numerical model, progressive damage was restricted to a predetermined ductile tearing zone. The material damage behaviour in this tearing zone was described in terms of a Gurson-Tvergaard (G-T) isotropic constitutive model, which accounts for micro-void nucleation and growth. The criterion for the onset of void coalescence was determined via the Thomason criterion. Experimentally measured load-displacement histories for all specimens were accurately reproduced by the proposed model, irrespective of different plate width, thickness and crack configurations. The numerical predictions were in good agreement with experimental test data in terms of both the maximum load and the corresponding displacement at maximum load. The proposed damage model was also used to numerically estimate the effect of crack growth on maximum load for these cracked specimens. The results in this paper demonstrate the potential of the proposed damage model as an engineering tool for analyzing ductile tearing in application to defect assessment of surface cracked pipes.

scholarly journals Modeling of the ORNL PCA Benchmark Using SCALE6.0 Hybrid Deterministic-Stochastic Methodology

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mario Matijević ◽  
Dubravko Pevec ◽  
Krešimir Trontl
Keyword(s):  
Cross Sections ◽  
Neutron Transport ◽  
National Laboratory ◽  
General Purpose ◽  
Monte Carlo Code ◽  
Oak Ridge ◽  
Benchmark Data ◽  
Selection Of ◽  
Good Agreement ◽  
Reactor Dosimetry

Revised guidelines with the support of computational benchmarks are needed for the regulation of the allowed neutron irradiation to reactor structures during power plant lifetime. Currently, US NRC Regulatory Guide 1.190 is the effective guideline for reactor dosimetry calculations. A well known international shielding database SINBAD contains large selection of models for benchmarking neutron transport methods. In this paper a PCA benchmark has been chosen from SINBAD for qualification of our methodology for pressure vessel neutron fluence calculations, as required by the Regulatory Guide 1.190. The SCALE6.0 code package, developed at Oak Ridge National Laboratory, was used for modeling of the PCA benchmark. The CSAS6 criticality sequence of the SCALE6.0 code package, which includes KENO-VI Monte Carlo code, as well as MAVRIC/Monaco hybrid shielding sequence, was utilized for calculation of equivalent fission fluxes. The shielding analysis was performed using multigroup shielding library v7_200n47g derived from general purpose ENDF/B-VII.0 library. As a source of response functions for reaction rate calculations with MAVRIC we used international reactor dosimetry libraries (IRDF-2002 and IRDF-90.v2) and appropriate cross-sections from transport library v7_200n47g. The comparison of calculational results and benchmark data showed a good agreement of the calculated and measured equivalent fission fluxes.

Probabilistic Structural Mechanics Analysis of the Degraded Davis-Besse RPV Head

2006 ◽  
Author(s):  
Paul T. Williams ◽  
Shengjun (Sean) Yin ◽  
B. Richard Bass
Keyword(s):  
National Laboratory ◽  
Damage Model ◽  
The United States ◽  
Structural Mechanics ◽  
Companion Paper ◽  
Experimental Program ◽  
Oak Ridge ◽  
Steel Technology ◽  
Sensitivity Studies ◽  
Technical Basis

The Heavy-Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) performed a probabilistic structural mechanics (PSM) analysis of the damaged Davis Besse reactor pressure vessel head in support of the United States Nuclear Regulatory Commission’s ongoing forensic investigations. This paper presents a summary of the results of that PSM analysis, including a description of the Davis-Besse wastage-area damage model, the technical basis for the model, and the results of sensitivity studies based on a cladding capacity analysis (CCA) and an Accident Sequence Precursor (ASP) investigation of the wastage cavity. A companion paper describes the HSST experimental program carried out at ORNL in parallel with the PSM analysis.

Finite Element Analysis and Experimental Study on the Behavior of Widened Beam Flange Connections of Steel Frame under Cyclic Loading

2011 ◽  
Vol 243-249 ◽  
pp. 948-952
Author(s):  
Hui Mao ◽  
Yan Wang ◽  
Cheng Hua Li
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Finite Element Models ◽  
Ansys Software ◽  
Element Analysis ◽  
Side Plate ◽  
Skeleton Curve ◽  
Failure Patterns ◽  
Plate Connections ◽  
Good Agreement

Based on the experiments of four connections with widened beam flange section which included two arc widened beam flange connections and two welded side-plate connections specimens and one ordinary connection under cyclic loading, 3-D nonlinear finite element models were created by using ANSYS software to analyze the mechanical properties of these two types of widened beam flange connections, such as skeleton curve, ultimate load, ductility and failure mode etc. The analytical results show good agreement with those of the experiments and prove the finite models correct and applicable. According to the experimental and element analytical failure results, the PI(PEEQ Index) was introduced to investigate the plasticity development and fracture tendency at the end of the widened flange part . Furthermore, the failure patterns of widened beam flange connection were revealed.

Development of specimen-specific finite element models of human vertebrae for the analysis of vertebroplasty

2008 ◽  
Vol 222 (2) ◽  
pp. 221-228 ◽  
Author(s):  
V N Wijayathunga ◽  
A C Jones ◽  
R J Oakland ◽  
N R Furtado ◽  
R M Hall ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Bulk Material ◽  
Image Data ◽  
Finite Element Models ◽  
Micro Computed Tomography ◽  
Bone Material ◽  
Automated Methods ◽  
Pmma Cement ◽  
Good Agreement

The aim of this study was to determine the accuracy of specimen-specific finite element models of untreated and cement-augmented vertebrae by direct comparison with experimental results. Eleven single cadaveric vertebrae were imaged using micro computed tomography (mCT) and tested to failure in axial compression in the laboratory. Four of the specimens were first augmented with PMMA cement to simulate a prophylactic vertebroplasty. Specimen-specific finite element models were then generated using semi-automated methods. An initial set of three untreated models was used to determine the optimum conversion factors from the image data to the bone material properties. Using these factors, the predicted stiffness and strength were determined for the remaining specimens (four untreated, four augmented). The model predictions were compared with the corresponding experimental data. Good agreement was found with the non-augmented specimens in terms of stiffness (root-mean-square (r.m.s.) error 12.9 per cent) and strength (r.m.s. error 14.4 per cent). With the augmented specimens, the models consistently overestimated both stiffness and strength (r.m.s. errors 65 and 68 per cent). The results indicate that this method has the potential to provide accurate predictions of vertebral behaviour prior to augmentation. However, modelling the augmented bone with bulk material properties is inadequate, and more detailed modelling of the cement region is required to capture the bone—cement interactions if the models are to be used to predict the behaviour following vertebroplasty.

The Analysis and Tests of Composite Leaf Spring for Trailer Truck

2013 ◽  
Vol 744 ◽  
pp. 383-387
Author(s):  
Jia Shi Wang ◽  
Zai Ke Li ◽  
Qi Bin Jiang ◽  
Wen Li Lv
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Weight Reduction ◽  
Load Capacity ◽  
Experimental Tests ◽  
Maximum Load ◽  
Leaf Spring ◽  
Environment Protection ◽  
Molding Process ◽  
Good Agreement

The composite leaf spring for trailer truck is developed with weight reduction 60% relative to steel spring, which can be benefit to environment protection and energy saving. In this work, the composite leaf spring is designed and analyzed by finite element method. Then the experimental tests are conducted on the composite leaf spring fabricated by the hot molding process. The spring rate and the maximum load capacity are measured, which have a good agreement with the design results.

Study on Numerical Simulation of Projectile Penetrating UHMWPE Fiber Layers and Effects of Projectile Parameters

2012 ◽  
Vol 630 ◽  
pp. 121-126
Author(s):  
Gong Wu Huang ◽  
Ai Jun Chen ◽  
Shao Min Luo ◽  
Cheng Xu
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
High Speed ◽  
Research Approach ◽  
Finite Element Models ◽  
Uhmwpe Fiber ◽  
Penetration Ability ◽  
The Relationship ◽  
Better Than ◽  
Good Agreement

Finite element models of bullet penetrating UHMWPE fiber layers are established to study the relationship between parameters of projectile and penetration ability using LS-DYNA software. The numerical simulation results of penetration calculated in Lagrange algorithm are in good agreement with the real experimental results, which verify the validity of the finite element models and algorithm. The numerical results show that high speed and small angle of attack can improve the penetration ability, the penetration ability of oval projectile is better than flat head projectile. A valid and reliable research approach for evaluating the design of protective equipment and efficiency of projectiles are proposed.

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