scholarly journals A finite element and experimental analysis of durability tested springs

2018 ◽  
Vol 165 ◽  
pp. 03017 ◽  
Author(s):  
Ying Wang ◽  
Constantinos Soutis ◽  
Lorenzo Gagliardi
Keyword(s):  
Finite Element ◽  
Experimental Analysis ◽  
Structural Integrity ◽  
Mechanical Tests ◽  
Test Machine ◽  
Fe Model ◽  
Original Design ◽  
Fe Simulations ◽  
Corrosion Pits

Ageing of vehicles has become a major concern as the vehicles reach the end of their original design life. Corrosion is part of long-term ageing and forms one of the critical degradation processes affecting the mechanical properties, such as stiffness, affecting the structural integrity and life of key components. In this study, a finite element and experimental analysis was carried out to investigate the response of corroded springs in relation to the morphology of a corroded surface. An FE model was created using ABAQUS that correlates the stiffness changes with ageing. The analysis of corrosion-induced stress is then performed to determine the stress fields within the corrosion region. The durability tested springs were analysed with a microscope to identify the morphology of corrosion pits; the measured pattern was adopted in the subsequent FE simulations. A spring test machine was employed to perform the mechanical tests. The load-deflection behaviour of durability tested springs was recorded and then was used to validate the FE simulations.

Lessons Learned From Operational Integrity of HP/HT Deepwater Pipelines

2019 ◽  
Author(s):  
Carlos O. Cardoso ◽  
Rafael F. Solano ◽  
Bruno R. Antunes
Keyword(s):  
Finite Element ◽  
High Pressures ◽  
Compressive Load ◽  
Lessons Learned ◽  
Fe Model ◽  
Special Device ◽  
Original Design ◽  
Element Analysis ◽  
Lateral Displacements

Abstract This paper addresses the results from a monitoring inspection as part of Petrobras regular plane of inspection of rigid pipelines (PIDR) and numerical Finite Element analysis (FEA) of two parallel HP/HT subsea pipelines operating in Brazilian deepwater subjected to lateral buckling and walking behaviors. The results obtained from inspection and numerical reanalysis furnishes important feedback for the integrity management of the two pipelines, reducing potential risks and lessons learned for future projects. Deepwater pipelines submitted to high pressures and temperatures (HP/HT) are susceptible to global buckling due to axial compressive load. To guarantee pipeline and equipment’s integrity frequently is necessary to relieve high stresses and strains at buckle apex as well as to mitigate end expansion. Thus, the two parallel HP/HT pipelines were designed with single and double sleepers to trigger buckles at pre-determined locations and an anchoring system to prevent pipeline walking. Another important design aspect was to avoid undesirable buckles at the several crossings along the pipeline route applying a special device with stoppers to lock lateral displacements. During a programmed inspection as part of regular Petrobras pipeline integrity program of rigid pipelines (PIDR), it has been verified that some double sleepers didn’t work as foreseen in design. Otherwise, some unplanned buckles on soil have been formed along the two pipelines changing the buckle apex stress levels and end expansions foreseen in detailed design. In order to understand buckle formation behavior and guarantee long-term integrity of the HP/HT pipelines a Multi-Beam Echosounder Survey (MBES) was conducted in 2016 to build a representative Finite Element (FE) model. The temperature and pressure gradients from steady state and transient conditions were obtained from flow assurance simulations based on monitored platform operational historic data. The FE model was calibrated with buckle shapes and end displacements to assess pipeline behavior and its long-term integrity for load scenarios different from original design.

Integrity Assessment of a Free-Fall Lifeboat Launched From a FPSO

2015 ◽  
Author(s):  
Guomin Ji ◽  
Nabila Berchiche ◽  
Sébastien Fouques ◽  
Thomas Sauder ◽  
Svein-Arne Reinholdtsen
Keyword(s):  
Finite Element ◽  
Pressure Distribution ◽  
Structural Integrity ◽  
Dynamic Effect ◽  
Sensitivity Study ◽  
Computational Time ◽  
Load Factor ◽  
Time Varying ◽  
Integrity Assessment

The paper addresses the structural integrity assessment of lifeboat launched from floating production, storage and offloading (FPSO) vessels. The study is based on long-term drop lifeboat simulations accounting for more than 50 years of hindcast data of metocean conditions and corresponding FPSO motions. Selection of the load cases and strength analyses with high computational time is a challenge. The load cases analyzed are those corresponding to the 99th percentile of long term distribution of indicators for large slamming loads (CARXZ) or large submergence (Imaxsub). For six selected cases, the time-varying pressure distribution on the lifeboat hull during and after water impact is calculated by CFD simulations using StarCCM+. The finite element model (FEM) of the composite structure of the lifeboat is modelled by ABAQUS. Quasi-static finite element (FE) analyses are performed for the selected load cases. The structural integrity is assessed by the maximum stress and Tsai-Wu failure measure. In the present study, the load and resistance factors are combined and applied to the response. A sensitivity study is performed to investigate the non-linear load/response effects when the load factor is applied to the load. In addition, dynamic analysis is performed with the time-varying pressure distribution for selected case and the dynamic effect is investigated.

Evaluation of Residual Stresses in Butt Welded Joint of Dissimilar Material by FEM

2017 ◽  
Vol 754 ◽  
pp. 268-271 ◽  
Author(s):  
Raffaele Sepe ◽  
M. Laiso ◽  
A. de Luca ◽  
Francesco Caputo
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Arc Welding ◽  
Structural Integrity ◽  
Welded Joint ◽  
Dissimilar Material ◽  
Fe Model ◽  
Butt Joints ◽  
Integrity Assessment ◽  
Steel Joints

The study proposed within this paper deals with an application of finite element techniques to the thermo-structural analysis of a dissimilar butt-welded joint. Residual stresses induced by the fusion arc-welding of steel joints in power generation plants are a concern to the industry. Nowadays, the application of finite element method appears to be a very efficient method for the prediction and the investigation of the weld-induced residual stresses, nevertheless the detailed modelling of all phenomena involved in such process is still challenging. The structural integrity assessment of welded structures strongly requires a deep investigation of weld-induced residual stresses in order to be compliant with safety requirement of power plant. The longitudinal and transversal residual stresses in dissimilar material butt joints of 8 mm thick for V-groove shape were studied. The developed thermo-mechanical FE model as well as the simulation procedures are detailed and results are discussed. As a result of such work, it has been found out that residual stresses in the two dissimilar plates are characterized by very different magnitudes and distribution.

Development of a Stochastic Approach for Vehicle FE Models

2003 ◽  
Author(s):  
David Riha ◽  
Joseph Hassan ◽  
Marlon Forrest ◽  
Ke Ding
Keyword(s):  
Finite Element ◽  
Reliability Analysis ◽  
System Reliability ◽  
Model Parameters ◽  
Fe Model ◽  
Original Design ◽  
Acceptance Criteria ◽  
Model Input ◽  
Input Parameters ◽  
Occupant Injury

This paper describes the development of a mathematical model capable of providing realistic simulations of vehicle crashes by accounting for uncertainty in the model input parameters. The approach taken was to couple advanced and efficient probabilistic and reliability analysis methods with well-established, high fidelity finite element and occupant modeling software. Southwest Research Institute has developed probabilistic analysis software called NESSUS. This code was used as the framework for a stochastic crashworthiness FE model. The LS-DYNA finite element model of vehicle frontal offset impact and the MADYMO model of a 50th percentile male Hybrid III dummy were integrated with NESSUS to comprise the crashworthiness characteristics. The system reliability of the vehicle is computed by defining ten acceptance criteria performance functions; four occupant injury criteria and six compartment intrusion criteria. The reliability for each acceptance criteria was computed using NESSUS to identify the dominant acceptance criteria of the original design. The femur axial load acceptance criteria event has the lowest reliability (46%) followed by the HIC event (58%) and the door aperture closure event (73%). One approach to improve the reliability is to change vehicle parameters to improve the reliability for the dominant criteria. However, a parameter change such as vehicle strength/stiffness may have a beneficial effect on certain acceptance criteria but be detrimental to others. A system reliability analysis was used to include the contribution of all acceptance criteria to correctly quantify the vehicle reliability and identify important parameters. A redesign analysis was performed using the computed probabilistic sensitivity factors. These sensitivities were used to identify the most effective changes in model parameters to improve the reliability. A redesign using 11 design modifications was performed that increased the original reliability from 23% to 86%. Several of the design changes include increasing the rail material yield strength and reducing its variation, reducing the variation of the bumper and rail installation tolerances, and increasing the rail weld stiffness and reducing its variation. The results show that major reliability improvements for occupant injury and compartment intrusion can be realized by certain specific modifications to the model input parameters. A traditional (deterministic) method of analysis would not have suggested these modifications.

A Finite Element Model for Ultrasonic Cutting of Toffee

2006 ◽  
Vol 5-6 ◽  
pp. 519-526 ◽  
Author(s):  
E. McCulloch ◽  
Alan MacBeath ◽  
Margaret Lucas
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Uniaxial Tensile ◽  
Test Machine ◽  
Fe Model ◽  
Temperature Dependent ◽  
Erosion Model ◽  
Element Erosion ◽  
Element Removal ◽  
Ultrasonic Cutting

The performance of an ultrasonic cutting device critically relies on the interaction of the cutting tool and the material to be cut. A finite element (FE) model of ultrasonic cutting is developed to enable the design of the cutting blade to be influenced by the requirements of the toolmaterial interaction and to allow cutting parameters to be estimated as an integral part of designing the cutting blade. In this paper, an application in food processing is considered and FE models of cutting are demonstrated for toffee; a food product which is typically sticky, highly temperature dependent, and difficult to cut. Two different 2D coupled thermal stress FE models are considered, to simulate ultrasonic cutting. The first model utilises the debond option in ABAQUS standard and the second uses the element erosion model in ABAQUS explicit. Both models represent a single blade ultrasonic cutting device tuned to a longitudinal mode of vibration cutting a specimen of toffee. The model allows blade tip geometry, ultrasonic amplitude, cutting speed, frequency and cutting force to be adjusted, in particular to assess the effects of different cutting blade profiles. The validity of the model is highly dependent on the accuracy of the material data input and on the accuracy of the friction and temperature boundary condition at the blade-material interface. Uniaxial tensile tests are conducted on specimens of toffee for a range of temperatures. This provides temperature dependent stress-strain data, which characterises the material behaviour, to be included in the FE models. Due to the difficulty in gripping the tensile specimens in the test machine, special grips were manufactured to allow the material to be pulled without initiating cracks or causing the specimen to break at the grips. A Coulomb friction condition at the bladematerial interface is estimated from experiments, which study the change in the friction coefficient due to ultrasonic excitation of a surface, made from the same material as the blade, in contact with a specimen of toffee. A model of heat generation at the blade-toffee interface is also included to characterise contact during ultrasonic cutting. The failure criterion for the debond model assumes crack propagation will occur when the stress normal to the crack surface reaches the tensile failure stress of toffee and the element erosion model uses a shear failure criterion to initiate element removal. The validity of the models is discussed, providing some insights into the estimation of contact conditions and it is shown how these models can improve design of ultrasonic cutting devices.

Avoid Exchanger Replacement Using Advanced Analysis and Fit for Service Approach

2021 ◽  
Author(s):  
Ibrahim M. Al Awadhi ◽  
Ashok M. Sharma ◽  
Sohail Akhter
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Heat Exchangers ◽  
Structural Integrity ◽  
Design Code ◽  
Element Analysis ◽  
Fit For Purpose ◽  
Design Pressure

Abstract Objective/Scope (25 - 75 word) Shell & Tube Heat exchangers are critical for incessant operation of processing plant. These exchangers may face integrity threats due to reduction in shell thicknesses at Nozzle to Shell Junction below design code requirements. This paper presents the Cost Effective fit for purpose approach utilizing advance Finite Element analysis to explore and recommend the solutions for existing numerous exchangers that are to be safely used even after reported low thickness on account of manufacturing imperfection. Methods, Procedures, Process (75 - 100 word) Reduction in Shell thickness below design value can affect its ability to sustain design pressure & vacuum including nozzle integrity for associated piping loads and service life reduction for exclusion of corrosion allowance. As short-term Mitigation methodology, weld overlay was adopted to restore the areas with lower thickness. For long term solution, fit for purpose review approach was adopted for continued usage of exchangers which involves nozzle load analysis using WRC & FEA based on PAUT thickness data and utilizing actual piping loads, derating of design pressure, comparison of thickness data to establish corrosion rate and service life of exchanger. Results, Observations & Conclusions (100 - 200 words) Thorough Integrity review based on design Code (ASME BPVC Section VIII) and WRC analysis have confirmed that majority of the exchangers have thickness higher than that required to sustain design pressure, vacuum conditions when considered with piping loads acting on nozzles. Thickness data comparison between three (03) year old manual UT and latest Phase array UT confirmed that majority of the exchangers are in clean non-corrosive service thus allowance for corrosion is not required. Where in the nature of exchanger service require corrosion allowance, it is considered in analysis and usage of stiffeners at nozzle to shell intersection and/or on full circumference of shell is recommended to prevent overstress due to piping loads / buckling distortion due to vacuum conditions respectively, based on detailed Finite element analysis (FEA). In order to establish more reliable long-term corrosion rate, next inspection after four (04) years is recommended and impact on integrity can be further evaluated based on the latest data. Change in exchanger nameplate is recommended to consider for design pressure as MAWP and accordingly adjust hydro test pressure followed by R-stamp requirements for rerating and repair. Shell side hydro test is restricted until recommendations are implemented Novel/Additive Information (25 - 75 words) Although conventional approach of replacing complete Shells to meet code requirement would have ensured process safety, performance and structural integrity. However, alternative fit for purpose approach utilizing advanced FEA has not only ensured all these but also led to potential cost saving of multimillion US$. Associated risks of thickness reduction due to corrosion may still be observed, however analysis confirmed structural integrity and safety of heat exchangers with low thicknesses. Accordingly, potential risk is mitigated.

scholarly journals Finite Element Modeling of FRP-Strengthened RC Beam under Sustained Load

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Shiyong Jiang ◽  
Weilai Yao ◽  
Jin Chen ◽  
Tao Cai
Keyword(s):  
Finite Element ◽  
Field Performance ◽  
Adhesive Layer ◽  
Aging Effect ◽  
Time Dependent ◽  
Sustained Load ◽  
Fe Model ◽  
Rc Beam ◽  
Long Term Behavior

External bonding of FRP laminates to the tension soffit of concrete members has become a popular method for flexural strengthening. However, the long-term field performance of FRP-strengthened RC members under service conditions is still a concern, and more work needs to be done. Based on concrete smeared-crack approach, this paper presents a finite-element (FE) model for predicting long-term behavior of FRP-strengthened RC beam, which considers the time-dependent properties of all components including the aging effect of concrete. According to the comparison between theoretical predictions and test results, the validity of the FE model is verified. The interfacial edge stresses in adhesive layer were determined through appropriate mesh refinement near the plate end, and their time-dependent characteristics were investigated. The results show that creep of concrete and epoxy resin cause significant variations of the edge stresses with time. According to the research in this paper, the FE approach is found to be able to properly simulate the long-term behavior of the FRP-strengthened beam and help us better understand the complex changes in the stress state occurring over time.

Improving Child Safety Seat Performance Through Finite Element Simulations

2014 ◽  
Author(s):  
Jingwen Hu ◽  
H. R. Raj Jayakar
Keyword(s):  
Finite Element ◽  
Safety Performance ◽  
Fe Model ◽  
Future Studies ◽  
Design Concepts ◽  
Test Conditions ◽  
Fe Simulations ◽  
Tube Shape ◽  
Frontal Crashes ◽  
Safety Seat

In this study, a finite element (FE) model of a child seat was developed. This model along with a HIII 6-year-old child ATD model was validated against four sled tests with different restraint conditions under FMVSS 213 test environments. The simulated results of ATD kinematics and restraint forces correlated well to the test data. In order to reduce the weight of the child seat while keeping its safety performance, different design concepts were explored by FE simulations with a mesh morphing method. It was found that lowering the height of child seat base can effectively reduce the weight and head/knee excursions in frontal crashes at the same time. Reducing the material in low stress areas would reduce the weight but slightly increase the ATD head and knee excursions in crashes. Overall, the modified design with reduced based height and reduced weight in low stress areas has a weight of 1.13 lbs less than the original seat, and the ATD head and knee excursions in FMVSS 213 test conditions with four different restraint conditions all reduced. In addition, it was found that changing the tube shape can potentially change the distribution of the head and knee excursions without much impact on weight. This study demonstrated the feasibility and usefulness for introducing FE simulations into the child seat design process. Future studies using this validated FE child seat model should focus on other crash scenarios, such as those with different impact severities and directions to improve safety performance of the child seat design.

scholarly journals Validation and Improvement of a Bicycle Crank Arm Based in Numerical Simulation and Uncertainty Quantification

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1814
Author(s):  
R. Gutiérrez-Moizant ◽  
M. Ramírez-Berasategui ◽  
José A. Calvo ◽  
Carolina Álvarez-Caldas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Structural Integrity ◽  
Fatigue Behavior ◽  
Dynamic Test ◽  
Element Model ◽  
Experimental Results ◽  
Original Design ◽  
Safety Requirements ◽  
Metrological Control

In this study, a finite element model of a bicycle crank arm are compared to experimental results. The structural integrity of the crank arm was analyzed in a universal dynamic test bench. The instrumentation used has allowed us to know the fatigue behavior of the component tested. For this, the prototype was instrumented with three rectangular strain gauge rosettes bonded in areas where failure was expected. With the measurements made by strain gauges and the forces registers from the load cell used, it has been possible to determine the state of the stresses for different loads and boundary conditions, which has subsequently been compared with a finite element model. The simulations show a good agreement with the experimental results, when the potential sources of uncertainties are considered in the validation process. This analysis allowed us to improve the original design, reducing its weight by 15%. The study allows us to identify the manufacturing process that requires the best metrological control to avoid premature crank failure. Finally, the numerical fatigue analysis carried out allows us to conclude that the new crank arm can satisfy the structural performance demanded by the international bicycle standard. Additionally, it can be suggested to the standard to include the verification that no permanent deformations have occurred in the crank arm during the fatigue test. It has been observed that, in some cases this bicycle component fulfils the minimum safety requirements, but presents areas with plastic strains, which if not taken into account can increase the risk of injury for the cyclist due to unexpected failure of the component.

Finite Element Analysis of a Hobie 16 Mast and Possible Alternatives for Improvement

2014 ◽  
Author(s):  
Mosfequr Rahman ◽  
Bryan Calloway ◽  
Eric Sullivan ◽  
Matthew Darley ◽  
Anthony Hanson ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Structural Integrity ◽  
Center Of Gravity ◽  
Original Design ◽  
Element Analysis ◽  
Baseline Design ◽  
Depth Analysis ◽  
Aluminum Alloy 7075

Hobie Cat is one of the most popular sailboat production companies to ever exist, and the Hobie 16 is the most popular boat in the Hobie Cat line-up. The key to Hobie’s success was largely in part to advancements in strong and lightweight materials. This advancement allowed Hobie to achieve record breaking performance in their particular class of boat. The mast of the Hobie 16 is one of the heavier pieces of the craft. The overall mass and center of mass is greatly affected by this component, which begs to question if there may possibly be room for improvement. A sailboat mast is defined as a tall vertical spar, sometimes sectioned, that rises from the keel or deck of a sailing vessel to support the sails and the standing and running rigging. Sailboat masts are long, slender structures. They must be designed to be able to hold the thrust loads that are acting on them from the sails which will differ based on wind conditions. A mast must also be made of a material that will allow it to go through the varying environmental conditions without fatiguing. When designing a sailboat mast a few of the main goals are to have a low center of gravity, be light weight, and also aerodynamically efficient. During this research a Hobie 16 mast design was taken as a baseline design for testing. The current mast on the market weighs between 50–60 lbs. While this is not extremely heavy, the center of gravity is approximately 13.5 feet from the end of the mast. This high center of gravity makes it tough to raise and lower the mast when launching the boat. One important objective in this work is to create a mast that will be easier for the user to raise and lower without sacrificing the structural integrity of the mast. Three masts have been created in solid modeling software, and their performance characteristics have been tested using finite element analysis software ANSYS. Two of the designs are original works, while one is a copy of the original Hobie Cat design. The original design was analyzed, providing baseline data for which to compare the new designs with. In addition to the new designs, all designs have been constructed from three different materials as Aluminum Alloy 6061, Aluminum Alloy 7075 and Acrylic. This allows for comparison of designs and possible new materials. After an in depth analysis of all masts, the recommendation is made that Hobie 16 users would benefit greatly from the use of a tapered mast made of aluminum alloy 7075.

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