scholarly journals Structural Integrity Evaluation of Jackets Submitted to Through Cracks

2002 ◽  
Author(s):  
Antoine Rouhan ◽  
Franck Schoefs
Keyword(s):  
Finite Element ◽  
Probabilistic Model ◽  
Structural Integrity ◽  
Detection Theory ◽  
False Alarms ◽  
Structural Behaviour ◽  
Maintenance Costs ◽  
The Impact

The study of the impact of through cracks on structural integrity of jacket platforms still a challenge. The detection of such cracks is of great importance and a miss, or a spurious indication can lead to maintenance costs overrun. In the context of risk-based inspection and monitoring of such structures, a global methodology is proposed. The detection of large cracks is first addressed. A probabilistic model is proposed, taking into account the in situ inspections performances and the probability of crack presence. This is achieved by the use of the detection theory. Second, a finite element that is able to represent the structural behaviour of through cracked tubular nodes is proposed and a global structural integrity measure is suggested. Finally, inspection results are introduced in order to compute the expected platform structural integrity. It is illustrated by considering FMD inspections results of a tripod structure. Effects of false alarms can then be underlined.

scholarly journals Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

2015 ◽  
Vol 12 (19) ◽  
pp. 5871-5883 ◽  
Author(s):  
L. A. Melbourne ◽  
J. Griffin ◽  
D. N. Schmidt ◽  
E. J. Rayfield
Keyword(s):  
Climate Change ◽  
Finite Element ◽  
Structural Integrity ◽  
Geometric Model ◽  
Algal Growth ◽  
Coralline Algae ◽  
Rocky Shores ◽  
Element Analysis ◽  
Scan Data ◽  
The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

The measurement of groundwater temperature in shallow piezometers and standpipes

2005 ◽  
Vol 42 (5) ◽  
pp. 1377-1390 ◽  
Author(s):  
Matthew D Alexander ◽  
Kerry TB MacQuarrie
Keyword(s):  
Finite Element ◽  
Statistical Analysis ◽  
Transport Model ◽  
Shallow Groundwater ◽  
Subsurface Temperature ◽  
Groundwater Temperature ◽  
Monitoring Well ◽  
Laboratory Results ◽  
The Impact

Accurate measurements of in situ groundwater temperature are important in many groundwater investigations. Temperature is often measured in the subsurface using an access tube in the form of a piezometer or monitoring well. The impact of standpipe materials on the conduction of heat into the subsurface has not previously been examined. This paper reports on the results of a laboratory experiment and a field experiment designed to determine if different standpipe materials or monitoring instrument configurations preferentially conduct heat into the shallow sub surface. Simulations with a numerical model were also conducted for comparison to the laboratory results. Statistical analysis of the laboratory results demonstrates that common standpipe materials, such as steel and polyvinylchloride (PVC), do not affect temperature in the subsurface. Simulations with a finite element flow and heat transport model also confirm that the presence of access tube materials does not affect shallow groundwater temperature measurements. Field results show that different instrument configurations, such as piezometers and water and air filled and sealed well points, do not affect subsurface temperature measurements.Key words: groundwater temperature, temperature measurement, conduction, piezometers, piezometer standpipes, thermal modelling.

scholarly journals Particle Finite Element Simulation of Chip Formation in Cutting Processes

2017 ◽  
Vol 869 ◽  
pp. 50-61
Author(s):  
Matthias Sabel ◽  
Christian Sator ◽  
Ralf Müller ◽  
Benjamin Kirsch
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Large Deformations ◽  
Element Formulation ◽  
Particle Finite Element Method ◽  
Element Simulation ◽  
Modeling Techniques ◽  
Cutting Processes ◽  
The Impact ◽  
Cutting Simulations

The formation of chips in cutting processes is characterised by large deformations and large configurational changes and therefore challenges established modeling techniques. To overcome these difficulties, the particle finite element method (PFEM) combines the benefits of discrete modeling techniques with methods based on continuum mechanics. In this work an outline of the PFEM, as well as an explanation of the finite element formulation are provided. The impact of the boundary detection on the structural integrity is studied. The numerical examples include a tensile test as well as cutting simulations. The paper is concluded by a comparison of cutting forces with analytical results.

Finite Element Dynamic Analysis of a Railway Seat Under Longitudinal Impact Condition

2011 ◽  
Author(s):  
Francesco Caputo ◽  
Giuseppe Lamanna ◽  
Alessandro Soprano
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Seat Belt ◽  
Element Model ◽  
Railway Vehicle ◽  
Longitudinal Impact ◽  
Structural Behaviour ◽  
Structural Dynamic ◽  
Sled Test ◽  
Seat Frame

For a railway vehicle, the structural integrity of the seat frame and of its connection to that of the coach is a very important aspect of the design phase addressed to the improvement of the passive safety performances, at most because the analysis of the accidents occurred in recent years shows that secondary impacts against vehicle interiors remain one of the main causes of injury. All regulations which apply to this task start from the assumption that whatever happens to the vehicle the seat must remain connected to the vehicle frame, as well as the different parts to each other. Numerical evaluations are obviously necessary to match with this design requirement; it would be desirable to apply multi-body (MB) codes to this task, as they are really fast, but unfortunately they can’t provide detailed results for what concerns the structural behaviour of the involved seat and vehicle components. For this reason, in the present work a full finite element model of a sled-test, including a FE dummy, has been developed, analysed and validated by comparison with the available experimental results; it has been also showed how this kind of numerical simulation is suited and necessary to evaluate the structural behaviour of the structural components of the seat frame. In the context of the presented study the MADYMO® code has been adopted to perform the preliminary MB analyses necessary to calibrate and evaluate the relevant parameters of dummy-seat contact surfaces and of seat-belt stiffness, while LS DYNA® code has been used for the structural dynamic FE analyses.

Concrete LNG GBS Terminal Ship Collision Study

2008 ◽  
Author(s):  
Fuqiang Wu ◽  
Frank Puskar ◽  
Pascinthe Saad
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Integrity ◽  
Impact Resistance ◽  
Liquefied Natural Gas ◽  
Element Analysis ◽  
Benchmark Tests ◽  
Ship Collision ◽  
Numerical Tool ◽  
The Impact

Concrete Gravity Based Structure (GBS) provides an opportunity for the storage of Liquefied Natural Gas (LNG) and represents one of the key elements of an LNG receiving and regasification terminal. The impact resistance of an offshore LNG GBS against accidental ship collision needs to be evaluated. Nonlinear elasto-plastic Finite Element Analysis (FEA) provides a useful numerical tool to assess the damage and evaluate the overall structural integrity of the GBS following a ship collision. In the work presented, a large capacity tanker was modeled using FEA and simulated to collide into a prototype concrete LNG GBS. An efficient, two-step approach was applied to estimate the damage levels caused by the striking tanker considering different approach speeds. Various benchmark tests were conducted to validate the steel and concrete FEA models to ensure the reliability of the analysis. The simulation shows that certain collisions can cause damage to both the tanker bow and the LNG GBS, depending upon the collision speed and the configuration of the colliding bodies. However, these collisions do not always result in a breach of the LNG containment. The results of this type of assessment can be used to assist in designing the LNG GBS to improve its impact resistance. The results can also be used in risk studies typical of these types of facilities.

EFFECT OF DOUBLE BOTTOM HEIGHT ON THE STRUCTURAL BEHAVIOUR OF BULK CARRIERS

2021 ◽  
Vol 153 (A4) ◽  
Author(s):  
P D Contraros ◽  
S P Phokas
Keyword(s):  
Finite Element ◽  
Structural Reliability ◽  
Structural Integrity ◽  
Minimum Level ◽  
Bulk Carrier ◽  
Structural Behaviour ◽  
Height Reduction ◽  
Bulk Carriers ◽  
Direct Calculations ◽  
Initial Focus

This is the first of a series of companion papers that the authors propose to present on the effect that the new CSR Rules will have on the design of bulk carriers. Our initial focus will be on the new design framework established for the inner bottom height of such vessels, a parameter critical to their structural integrity. It examines the effect that double bottom height reduction has on the reliability of the bulk carrier structure, by applying a finite element 3D - 3 hold analysis of varying double bottom heights to a typical current Panamax bulk carrier design. The results are compared to pre and post IACS CSR[2] requirements. The conclusion reached is that the establishing of the double bottom height should not be left to direct calculations. A minimum acceptable height should be established in order to maintain a minimum level of structural reliability and safety.

Ballistic penetration damages and energy absorptions of stacked cross-plied composite fabrics and laminated panels

2020 ◽  
Vol 29 (9) ◽  
pp. 1465-1484
Author(s):  
Qingsong Wei ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Impact Damage ◽  
Ballistic Impact ◽  
Body Armor ◽  
Element Analysis ◽  
Laminated Panels ◽  
Composite Fabrics ◽  
The Impact ◽  
Ballistic Penetration

Flexible fabrics have been widely used in body armor designs. Here we report ballistic impact damage of stacked cross-plied composite fabric and cross-plied laminated panels. The ballistic impact behaviors of stacked cross-plied composite fabric and cross-plied laminated panel have been tested with fragment-simulating projectiles under the strike velocity 550–600 m/s to explore the influence of the layers combination of fabric target on ballistic impact. Two types of macroscopic anisotropy continua finite element models based on fabric targets structures are established to analyze the ballistic mechanism of stacked cross-plied composite fabric and cross-plied laminated panels. The impact damage morphologies and energy absorptions have also been compared between the tests and finite element analysis results. We have found the stacked fabric construction absorbed more energy than their counterpart cross-plied laminated panel, while the laminated panel shows better structural integrity and stability during ballistic penetration.

Use of nondestructive testing to establish mechanistic-based seasonal load-carrying capacity of thin-paved highways in Saskatchewan

2008 ◽  
Vol 35 (7) ◽  
pp. 708-715 ◽  
Author(s):  
Curtis Berthelot ◽  
Erin Stuber ◽  
Diana Podborochynski ◽  
Jena Fair ◽  
Brent Marjerison
Keyword(s):  
Carrying Capacity ◽  
Structural Integrity ◽  
Rate Of Change ◽  
Load Carrying Capacity ◽  
Road Transportation ◽  
Load Carrying ◽  
Frost Depth ◽  
Thaw Depth ◽  
The Impact

It has long been known that increased load-carrying capacity during the winter months is very beneficial to rural road transportation in Saskatchewan. However, it has been observed that rapid weakening of thin-paved roads during spring thaw is highly detrimental to the load-carrying capacity of these roads. Direct measures of the structural integrity of Saskatchewan roads as a function of seasonal changes have not been quantified in the past. The objective of this study was to directly quantify the impact frost action has on the load-carrying capacity of thin-surfaced roads. This study examined the magnitude and rate of change of in situ structural deflection responses of a typical Saskatchewan thin-surfaced road during fall freeze-up and spring thaw in 2006–2007. This study showed that structural deflection responses significantly improved with frost depth greater than 50 cm and that deflection response significantly worsened with minimal thaw depth, as expected. The data obtained also indicated a significant increase in nonlinear strain weakening behavior during fall freeze-up at frost depths less than 50 cm. Therefore, based on the findings of this study, the frost thickness and the rate of change in frost thickness need to be directly considered in the fall and in the spring when calculating seasonal load limits of thin-paved roads.

scholarly journals Structural Integrity of Conventional and Modified Railroad Bearing Adapters for Onboard Monitoring

2014 ◽  
Author(s):  
Joseph Montalvo ◽  
Alexis Trevino ◽  
Arturo A. Fuentes ◽  
Constantine M. Tarawneh
Keyword(s):  
Finite Element ◽  
Structural Integrity ◽  
Element Model ◽  
Operating Conditions ◽  
Finite Element Analyses ◽  
Distribution Maps ◽  
Bearing Condition Monitoring ◽  
Monitoring Applications ◽  
Railroad Bearing ◽  
The Impact

This paper presents a detailed study of the structural integrity of conventional and modified railroad bearing adapters for onboard monitoring applications. Freight railcars rely heavily on weigh bridges and stations to determine cargo load. As a consequence, most load measurements are limited to certain physical railroad locations. This limitation provided an opportunity for an optimized sensor that could potentially deliver significant insight on bearing condition monitoring as well as load information. Bearing adapter modifications (e.g. cut-outs) were necessary to house the sensor and, thus, it is imperative to determine the reliability of the modified railroad bearing adapter, which will be used for onboard health monitoring applications. To this end, this study quantifies the impact of the proposed modifications on the adapter structural integrity through a series of experiments and finite element analyses. The commercial software Algor 20.3TM is used to conduct the stress finite element analyses. Different loading scenarios are simulated with the purpose of obtaining the conventional and modified bearing adapter stresses during normal and abnormal operating conditions. This information is then used to estimate the lifetime of these bearing adapters. Furthermore, this paper presents an experimentally validated finite element model which can be used to attain stress distribution maps of these bearing adapters in different service conditions. The maps are also useful for identifying areas of interest for an eventual inspection of conventional or modified railroad bearing adapters in the field.

scholarly journals Modeling the Effect of Fluid-Structure Interaction on the Impact Dynamics of Pressurized Tank Cars

2009 ◽  
Author(s):  
Hailing Yu ◽  
Yim H. Tang ◽  
Jeffrey E. Gordon ◽  
David Y. Jeong
Keyword(s):  
Finite Element ◽  
Equation Of State ◽  
Structural Integrity ◽  
Fluid Structure Interaction ◽  
Fracture Initiation ◽  
Impact Dynamics ◽  
Impact Zone ◽  
Plastic Deformations ◽  
Structure Interaction ◽  
The Impact

This paper presents a computational framework that analyzes the effect of fluid-structure interaction (FSI) on the impact dynamics of pressurized commodity tank cars using the nonlinear dynamic finite element code ABAQUS/Explicit. There exist three distinct phases for a tank car loaded with a liquefied substance: pressurized gas, pressurized liquid and the solid structure. When a tank car comes under dynamic impact with an external object, contact is often concentrated in a small zone with sizes comparable to that of the impacting object. While the majority of the tank car structure undergoes elastic-plastic deformations, materials in the impact zone can experience large plastic deformations and be stretched to a state of failure, resulting in the loss of structural integrity. Moreover, the structural deformation changes the volume that the fluids (gas and liquid) occupy and consequently the fluid pressure, which in turn affects the structural response including the potential initiation and evolution of fracture in the tank car structure. For an event in which the impact severity is low and the tank car maintains its structural integrity, shell elements following elastic-plastic constitutive relations can be employed for the entire tank car domain. For events in which the impact severity is higher and the tank car is expected to be punctured, an equivalent plastic strain based fracture initiation criterion expressed as a function of stress triaxiality is adopted for the material in the tank car’s impact zone. The fracture initiation is implemented for ductile, shear and mixed fracture modes and followed by further material deterioration governed by a strain softening law. Multi-layered solid elements are employed in the impact zone to capture this progressive fracture behavior. The liquid phase is modeled with a linear Us–Up Hugoniot form of the Mie-Gru¨neisen equation of state, and the gas phase is modeled with the ideal gas equation of state. Small to moderate amounts of fluid sloshing are assumed for an impacted tank car in this study. As such, the FSI problem can be solved with the Lagrangian formulation of ABAQUS, and appropriate contact algorithms are employed to model the multi-phase interactions. The force, displacement and impact energy results from the finite element analysis show good correlations with the available shell (side) impact test data. The puncture energy of a tank car in a shell impact scenario is further analyzed. It is demonstrated that the FSI effect needs to be adequately addressed in an analysis to avoid overestimating the puncture resistance of a tank car in an impact event.

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