scholarly journals An effective methodology for drop test analysis and optimization of aerospace composite structures

2019 ◽  
Author(s):  
DC Pham
Keyword(s):  
Composite Structures ◽  
Impact Analysis ◽  
3D Structure ◽  
Structural Response ◽  
Drop Test ◽  
Computationally Efficient ◽  
Test Analysis ◽  
Design And Optimization ◽  
Structural Configurations ◽  
Modeling Strategy

An effective modeling strategy for drop test analysis of composite structures is proposed which allows engineers to generate feasible designs of complex structures undergoing impact. Traditional drop test analysis of 3D structural structures requires careful and detailed modeling and simulation, especially for composite materials where structural response may significantly vary upon changing the composite material properties, layup stacking or ply orientations. To account for various structural configurations, an optimization scheme that is computationally efficient is highly desired for composite design and analysis. This work illustrates a robust modeling strategy for drop test design and optimization of general composite structures by combining an explicit impact analysis of a 2D structural profile and subsequently a quasi-static analysis of the relevant 3D structure. This novel methodology is validated and shows good correlation with experimental results

scholarly journals An Optimization Tool for Impact Analysis of Composite Structures

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Impact Loading ◽  
Composite Structures ◽  
Impact Analysis ◽  
Failure Modes ◽  
Drop Test ◽  
Matrix Cracking ◽  
Computational Time ◽  
Failure Behavior ◽  
Test Analysis ◽  
Plane Failure

Composite materials exhibit complex failure behavior under impact loading especially such as that for composite landing gear structure. Possible failure modes in composites may include matrix cracking, fiber breakage, kinking, fiber-matrix debonding or delamination between composite plies. In order to better understand the damage mechanisms and non-linear response of composite structures under impact, complex geometries, materials, ply orientations and stacking sequence need to be considered. However, general drop test analysis for composite structures usually takes a lot of computational efforts, and it may be even more expensive for failure analysis and optimization when various structural geometries and design configurations are taken into account. This paper proposes a new methodology for evaluation and optimization of failure behavior of composite structures subjected to impact loading, whereby drop test analysis of composite structures is modeled by explicitly dynamics analysis of two-dimensional structures and implicit analysis of three-dimensional solid structures to predict delamination or out-of-plane failure. The above-mentioned modeling strategy helps speed up the optimization process and considerably save computational time and efforts. The proposed methodology together with reliable optimization algorithms and failure theory criteria are integrated and coded into a FE optimization tool by Python script. It is shown that the optimization tool effectively helps engineers and researchers perform optimization of general composite structures and fully take into account of various geometries, materials, loading configurations, composite stack-up and sequences and individual ply's orientation.

scholarly journals Effective modeling strategy for drop test analysis of composite curved beam

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Composite Structures ◽  
Drop Test ◽  
Time Dependent ◽  
Woven Fabric ◽  
Curved Beam ◽  
Test Model ◽  
Test Analysis ◽  
Isotropic Composite ◽  
Modeling Strategy ◽  
The Impact

Recent studies on the drop test analysis of composite structures mainly focus on the unidirectional or quasi-isotropic composite plates. Impact studies on the three-dimensional curved structures with woven fabric composite materials have received much less attention in the literature. This paper presents detailed experimental and computational investigations of the impact behavior of woven fabric Eglass E722-8HS composite curved beam. Experimental drop tests of the curved beam are performed from the drop test tower to obtain the impact forces and deformation at various locations of the beam. Quantitatively experimental observation reveals a discrepancy in the time-dependent reaction forces obtained between two legs of the beam and in the strains measured at correspondingly symmetric positions. To correctly rationalize the mechanical behavior as observed in the experiment, an effective drop test modeling strategy is proposed and implemented by Python script allowing the nonlinear time-dependent response of each leg of the beam to be effectively computed. The predicted results by the drop test model are compared to the experimental data and reasonably good correlations between experimental and numerical results are achieved.

scholarly journals Analytical and Experimental Simulation of Fan Blade Behaviour and Damage Under Bird Impact

1990 ◽  
Author(s):  
H. C. Teichman ◽  
R. N. Tadros
Keyword(s):  
Impact Analysis ◽  
Failure Modes ◽  
Structural Response ◽  
Analytical Models ◽  
Experimental Simulation ◽  
Experimental Program ◽  
Test Analysis ◽  
Contact Algorithm ◽  
Bird Impact ◽  
Fan Blade

An extensive analytical and experimental program has been undertaken to investigate the Foreign Object Damage resistance capabilities of external components for small gas turbofan engines. A transient nonlinear impact analysis has been used to predict the structural response of fan blades under bird ingestion conditions. This analysis is based on finite elements, a 3-D bird load model and an interactive structure-to-bird contact algorithm. Experiments were designed and carried out to record large blade deformations during bird impact, and were used to validate and calibrate the analytical models. The analytical models and testing program are described, and dominant fan blade response and failure modes are presented. Predicted results demonstrate good correlation with test. Analysis application to fan blade design and other engine components is recommended.

An intelligent data mining system for drop test analysis of electronic products

2001 ◽  
Vol 24 (3) ◽  
pp. 222-231 ◽  
Author(s):  
Chi Zhou ◽  
P.C. Nelson ◽  
Weimin Xiao ◽  
T.M. Tirpak ◽  
S.A. Lane
Keyword(s):  
Data Mining ◽  
Drop Test ◽  
Mining System ◽  
Test Analysis ◽  
Electronic Products ◽  
Data Mining System

A new approach for displacement and stress monitoring of tunnel based on iFEM methodology

2021 ◽  
Author(s):  
Pierclaudio Savino ◽  
Francesco Tondolo
Keyword(s):  
Input Data ◽  
Structural Response ◽  
Fem Analysis ◽  
Computational Procedure ◽  
Loading Conditions ◽  
Underground Structures ◽  
Stress Monitoring ◽  
Load Pattern ◽  
Structural Configurations ◽  
Structural Loading

Abstract Structural monitoring plays a key role for underground structures such as tunnels. Strain readings are expected to report structural conditions during construction and at the final delivery of the works. Furthermore, it is increasingly requested an extension to long-term monitoring from contractors with possible use of the same system in service during construction. A robust and efficient monitoring methodology from discrete strain measurements is the inverse Finite Element Method (iFEM), which allows to reconstruct the structural response without input data on the load pattern applied to the structure as well as material and inertial properties of the elements and therefore it is interesting for structural configurations affected by uncertain loading conditions, such as the tunnel. The formulation presented in this paper, based on the iFEM theory, is improved from the previous work available in literature for both the shape functions used and the computational procedure. Indeed, the approach allows to overcome inconsistencies related to structural loading conditions and a pseudo-inverse matrix preserve all the rigid body modes without imposing specific constraints which is typical for tunnels. Numerical validation of the iFEM procedure is performed by simulating the input data coming from a tunnel working in a heterogeneous soil under different loading conditions with direct FEM analysis.

scholarly journals A Multi-Objective Ground Motion Selection Approach Matching the Acceleration and Displacement Response Spectra

2018 ◽  
Vol 10 (12) ◽  
pp. 4659 ◽  
Author(s):  
Yabin Chen ◽  
Longjun Xu ◽  
Xingji Zhu ◽  
Hao Liu
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Structural Response ◽  
Response Spectra ◽  
Computationally Efficient ◽  
Ground Motion Selection ◽  
Displacement Response ◽  
Rc Frames ◽  
Selection Approach ◽  
Displacement Response Spectra

For seismic resilience-based design (RBD), a selection of recorded time histories for dynamic structural analysis is usually required. In order to make individual structures and communities regain their target functions as promptly as possible, uncertainty of the structural response estimates is in great need of reduction. The ground motion (GM) selection based on a single target response spectrum, such as acceleration or displacement response spectrum, would bias structural response estimates leading significant uncertainty, even though response spectrum variance is taken into account. In addition, resilience of an individual structure is not governed by its own performance, but depends severely on the performance of other systems in the same community. Thus, evaluation of resilience of a community using records matching target spectrum at whole periods would be reasonable because the fundamental periods of systems in the community may be varied. This paper presents a GM selection approach based on a probabilistic framework to find an optimal set of records to match multiple target spectra, including acceleration and displacement response spectra. Two major steps are included in that framework. Generation of multiple sub-spectra from target displacement response spectrum for selecting sets of GMs was proposed as the first step. Likewise, the process as genetic algorithm (GA), evolvement of individuals previously generated, is the second step, rather than using crossover and mutation techniques. A novel technique improving the match between acceleration response spectra of samples and targets is proposed as the second evolvement step. It is proved computationally efficient for the proposed algorithm by comparing with two developed GM selection algorithms. Finally, the proposed algorithm is applied to select GM records according to seismic codes for analysis of four archetype reinforced concrete (RC) frames aiming to evaluate the influence of GM selection considering two design response spectra on structural responses. The implications of design response spectra especially the displacement response spectrum and GM selection algorithm are summarized.

Analysis of Concrete Pavement Responses to Temperature and Wheel Loads Measured from Intrumented Slabs

1998 ◽  
Vol 1639 (1) ◽  
pp. 94-101 ◽  
Author(s):  
H. Thomas Yu ◽  
Lev Khazanovich ◽  
Michael I. Darter ◽  
Ahmad Ardani
Keyword(s):  
Structural Response ◽  
Plain Concrete ◽  
Negative Temperature ◽  
Concrete Pavement ◽  
Temperature Gradients ◽  
Critical Conditions ◽  
Test Analysis ◽  
Longitudinal Edge ◽  
Critical Edge ◽  
Using Data

The structural response of jointed plain concrete pavement slabs was evaluated using data obtained from instrumented slabs. The instrumented slabs were a part of newly constructed jointed plain concrete overlay that was constructed on existing asphalt concrete pavement on I–70 in Colorado, near the Kansas–Colorado border. The instrumentation consisted of dial gauges for measuring curling deflections at the slab corner and longitudinal edge and surface-mounted strain gauges for measuring load strains at the longitudinal edge at midslab. The through-thickness temperature profiles in the pavement slabs were also measured at 30-min intervals during the field test. Analysis of the field data showed that the instrumented slabs had a considerable amount of built-in upward curling and that concrete slabs on a stiff base can act completely independent of the base or monolithically with the base, depending on the loading condition. The built-in upward curling of the slabs has the same effect as negative temperature gradients. These findings suggest that the effects of temperature gradients on the critical edge stresses may not be as great as previously thought and that the corner loading, in some cases, may produce more critical conditions for slab cracking. Another important finding of this study is that a physical bond between pavement layers is not required to obtain a bonded response from concrete pavements.

scholarly journals 4.2 - Optical 3D Methods in Steel Sheet Container Drop Test Analysis

2013 ◽  
Author(s):  
K.-P. Gründer ◽  
D. Kadoke ◽  
C. Protz ◽  
U. Zencker
Keyword(s):  
Steel Sheet ◽  
Drop Test ◽  
Test Analysis ◽  
3D Methods
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