Evaluation of finite element models of seat structures with integrated safety belts using full-scale experiments

Purpose This research was aimed at investigating the fire performance of LSF wall systems by using 3-D heat transfer FE models of existing LSF wall system configurations. Design/methodology/approach This research was focused on investigating the fire performance of LSF wall systems by using 3-D heat transfer finite element models of existing LSF wall system configurations. The analysis results were validated by using the available fire test results of five different LSF wall configurations. Findings The validated finite element models were used to conduct a parametric study on a range of non-load bearing and load bearing LSF wall configurations to predict their fire resistance levels (FRLs) for varying load ratios. Originality/value Fire performance of LSF wall systems with different configurations can be understood by performing full-scale fire tests. However, these full-scale fire tests are time consuming, labour intensive and expensive. On the other hand, finite element analysis (FEA) provides a simple method of investigating the fire performance of LSF wall systems to understand their thermal-mechanical behaviour. Recent numerical research studies have focused on investigating the fire performances of LSF wall systems by using finite element (FE) models. Most of these FE models were developed based on 2-D FE platform capable of performing either heat transfer or structural analysis separately. Therefore, this paper presents the details of a 3-D FEA methodology to develop the capabilities to perform fully-coupled thermal-mechanical analyses of LSF walls exposed to fire in future.

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Computational Modeling and Performance Evaluation of a DAX-Foam Aircraft Seat Cushion Utilizing High Loading Rate Dynamic Characteristics

Volume 11: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering, Risk Analysis and Reliability Methods; Transportation Systems ◽

10.1115/imece2010-40579 ◽

2010 ◽

Cited By ~ 1

Author(s):

Prasannakumar S. Bhonge ◽

Chandrashekhar K. Thorbole ◽

Hamid M. Lankarani

Keyword(s):

Finite Element ◽

Loading Rate ◽

Full Scale ◽

High Loading ◽

Finite Element Models ◽

Test Results ◽

Sled Test ◽

Seat Cushion ◽

High Loading Rate ◽

The Cost

The aircraft seat dynamic performance standards as per CFR 14 FAR Part 23, and 25 requires the seat to demonstrate crashworthy performance as evaluated using two tests namely Test-I and Test-II conditions. Test-I dynamic test includes a combined vertical and longitudinal dynamic load to demonstrate the compliance of lumbar load requirement for a Hybrid II or an FAA Hybrid III Anthropomorphic Test Device (ATD). The purpose of this test is to evaluate the means by which the lumbar spine of the occupant in an impact landing can be reduced. This test requirement is mandatory with every change in the seat design or the cushion geometry. Experimental full-scale crash testing is expensive and time-consuming event when required to demonstrate the compliance issue. A validated computational technique in contrast provides an opportunity for the cost effective and fast certification process. This study mainly focuses on the characteristics of DAX foams, typically used as aircraft seat cushions, as obtained both at quasi-static loading rate and at high loading rate. Nonlinear finite element models of the DAX foam are developed based on the experimental test data from laboratory test results conducted at different loading rates. These cushion models are validated against sled test results to demonstrate the validity of the finite element models. The results are compared for these computational sled test simulations with each seat cushion as obtained using quasi-static and high-loading rate characteristics. The result demonstrates a better correlation of the simulation data with the full scale crash test data for the DAX foam when high loading rate data is utilized instead of quasi-static data in the dynamic finite element models. These models can be utilized in the initial design of the aircraft seats, and thus reducing the cost and time of a full-scale sled test program.

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Prediction of Vehicle Crashworthiness Parameters Using Piecewise Lumped Parameters and Finite Element Models

10.20944/preprints201809.0009.v1 ◽

2018 ◽

Author(s):

Bernard B. Munyazikwiye ◽

Dmitry Vysochinskiy ◽

Mikhail Khadyko ◽

Kjell G. Robbersmyr

Keyword(s):

Finite Element ◽

Computation Time ◽

Severity Index ◽

Full Scale ◽

Crash Test ◽

Finite Element Models ◽

Element Analysis ◽

Nonlinear Springs ◽

Lumped Parameters ◽

Vehicle Crashworthiness

Estimating the vehicle crashworthiness parameters experimentally is expensive and time consuming. For these reasons different modelling approaches are utilized to predict the vehicle behaviour and reduce the need for full-scale crash testing. The earlier numerical methods used for vehicle crashworthiness analysis were based on the use of lumped parameters models (LPM), a combination of masses and nonlinear springs interconnected in various configurations. Nowadays, the explicit nonlinear finite element analysis (FEA) is probably the most widely recognized modelling technique. Although informative, finite element models (FEM) of vehicle crash are expensive both in terms of man-hours put into assembling the model and related computational costs. A simpler analytical tool for early analysis of vehicle crashworthiness could greatly assist the modelling and save time. In this paper a simple piecewise LPM composed of a mass-spring-damper system, is used to estimate the vehicle crashworthiness parameters, focusing on the dynamic crush and the acceleration severity index (ASI). The model is first calibrated against a full-scale crash test and a FEM, post-processed with the LS-DYNA software, at an impact velocity of 56 km/h. The genetic algorithm is used to calibrate the model by estimating the piecewise lumped parameters (stiffness and damping of the front structure of the vehicle). After calibration, the LPM is applied to a range of velocities (40, 48, 64 and 72 km/h). The predictions for crashworthiness parameters from the LPM were compared with the predictions from the FEA and the results are much similar. It is shown that the LPM can assist in crash analysis, since LPM has some predictive capabilities and requires less computation time in comparison with the explicit nonlinear FEA.

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Remaining Collapse Capacity of Corroded Pipelines

Volume 4: Pipeline and Riser Technology ◽

10.1115/omae2011-49054 ◽

2011 ◽

Cited By ~ 2

Author(s):

Qishi Chen ◽

Mark Marley ◽

Joe Zhou

Keyword(s):

Experimental Data ◽

Finite Element ◽

Wall Thickness ◽

Numerical Models ◽

Substantial Reduction ◽

Assessment Method ◽

Full Scale ◽

Finite Element Models ◽

Pipe Material ◽

Corrosion Defects

It is known that, for given pipe material and diameter, collapse capacity of a plain pipe subjected to external pressure is proportional to the second or third power of wall thickness. In lieu of sophisticated numerical models and experimental data, conservative approaches such as those in which thickness losses at corrosion defects are extended to the entire circumference have been adopted in practices to assess the collapse resistance of corroded pipes. This reduced wall thickness is then used in the design equation of plain pipe to predict remaining collapse capacity. Such conservative assumptions result in substantial reduction of collapse capacity for pipelines with localized corrosion defects. During the course of a multiple-year PRCI research project, results of full-scale collapse tests and three-dimensional finite element analysis demonstrated that the reduction of collapse capacity was less than 10% for defects with a depth of 50% wall thickness, an axial length of one diameter and a circumferential width of half a diameter. These findings illustrated that the actual collapse capacity of corroded pipes is significantly higher than that estimated according to the conservative assumptions. This paper presents the development of a reliability-based, practical assessment method that allows remaining collapse capacity of corroded pipelines be determined based on defect size data obtained from in-line inspections. Work involved included characterization of corrosion defects, full-scale collapse tests, validation of finite element models using experimental data, analysis of parametric cases using finite element models, development of empirical equation based on experimental and numerical results, and calibration of partial safety factors which addressed the uncertainties associated with model error, load variation, and sizing inaccuracy of corrosion defects. Practical implications of the proposed assessment method were evaluated based on selected examples.

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