Objective Of Structural Design Research Articles

Study on Impact Mechanical Properties of Reentrant Bionic Automotive Energy Absorbing Box.

In order to impprove the protective effect of the automotive energy absorption (EA) box, the design of the reentrant bioinspired EA box is proposed, that is, novel bioinspired structures are inserted into the original EA box to improve the EA effect of the box. The improved bionic structures with curvature are designed according to the spider web: honeycomb structure (HS), arc-honeycomb structure (AHS), negative Poisson structure (PS), and arc negative Poisson structure (APS). A new bionic automobile energy absorbing box is constructed by combining with automobile energy absorbing box. Experiments and simulations further verify excellent mechanical properties of bionic structures. The results show that EA of AHS and APS is 117.2% and 105.8% of HS and PS. Their specific energy absorption is 112.2% and 102.7% of HS and PS. HS EA box structure, AHS energy absorption box structure, PS energy absorption box structure, and APS energy absorption box structure are 114.2%, 117%, 109.2%, and 116.2% higher than traditional EA box structures, respectively. The excellent characteristics of biological structures can provide ideas for structural design objectives of engineering applications and greatly simplify the process of optimal design.

Sensitivity Analysis Based NVH Optimization in Permanent Magnet Synchronous Machines Using Lumped Unit Force Response

Acoustic noise and vibration sources in electric machines are mainly of electromagnetic and structural origin. A lumped structural unit response-based sensitivity analysis procedure is proposed in this article, which isolates electromagnetic and structural impacts brought by variation of different design parameters in a fractional slot concentrated winding, surface mounted permanent magnet synchronous machine (SPMSM). The impact of ten design parameters on average torque, torque ripple, synchronous inductance, dominant spatial-temporal order airgap force, cogging torque, friction torque, dominant mode frequency and structural unit response is studied in detail for a 12 slot/10 pole (12s10p) SPMSM. Analysis reveals that on a 12s10p SPMSM, slot opening has a very high impact on dominant airgap force component. A multilevel nonlinear regression model-based fast optimization strategy is introduced considering electromagnetic and structural design objectives and constraints following the sensitivity analysis. The optimized design is prototyped to validate the proposed design approach. Impact hammer-based modal analysis, no load, load and run-up tests are performed on the prototype for experimental validation. Ranging from structural tests to electromagnetic tests, the experimental results closely follow and validate the simulation-based predictions.

Finite Element Model for the Optimization of Steel I-Beam with Variable Depth

The objective of structural design is to select member sizes with the optimal proportioning of the overall structural geometry. Conventional steel I-beam with variable depth have been used widely in various engineering fields. The objective of this study is to develop a three-dimensional finite element model for the total volume of steel I-beam with variable depth. The finite element software package ANSYS was used to determine the optimum total volume for the steel I-beam with variable depth. The purpose of the study is to minimize the total volume of the steel beam. The design variables are the height of the steel beam at support, the flanges width, the thickness of flanges, the height of the steel beam at mid-span, and the web thickness. The constraints considered in this study are the normal stress in steel beam and the mid-span displacement of the steel beam. Optimization results of steel beam indicate that the total volume was reduced approximately by 52 %.

LPV-model based identification approach of oscillatory failure cases

The reliable early detection of oscillatory failure cases (OFC) for modern fly-by-wire controlled civil aircraft is an important aspect in optimizing the structural design objectives for reducing the environmental footprint of the aircraft. We propose a complete methodology for the design of a model based fault detection and diagnosis (FDD) system, which allows the reliable early detection of OFC characterized by low amplitude oscillations in a given frequency range. The main factors for the achieved enhanced performance are: the accurate modelling of the surface actuator via linear parameter-varying (LPV) models, an improved oscillation detection by employing the recursive discrete Fourier transform, and the integrated tuning of the free parameters of the FDD system using multi-objective optimization techniques.

Application of Soft Computing Based Response Surface Techniques in Sizing of A-Pillar Trim with Rib Structures

The paper proposes the fuzzy logic global approximate optimization strategies in optimal sizing of automotive A-pillar trim with rib structures for occupant head protection. Two different strategies referred to as evolutionary fuzzy modeling (EFM) and neuro-fuzzy modeling (NFM) are implemented in the context of global approximate optimization. EFM and NFM are based on soft computing paradigms utilizing fuzzy systems, neural networks and evolutionary computing techniques. Such approximation methods may have their promising characteristics in a case where the inherent nonlinearity in analysis model should be accommodated over the entire design space and the training data is not sufficiently provided. The objective of structural design is to determine the dimensions of rib in A-pillar, minimizing the equivalent head injury criterion HIC(d). The paper describes the head-form modeling and head impact simulation using LS-DYNA3D, and the approximation procedures including fuzzy rule generation, membership function selection and inference process for EFM and NFM, and subsequently presents their generalization capabilities in terms of number of fuzzy rules and training data.

Reliability‐Based Load and Resistance Factor Design (LRFD) of Hull Girders for Surface Ships

ABSTRACTThe main objective of structural design is to insure the safety, functional, and performance requirements of a structural system for target reliability levels, for a specified period of time, and for a specified environment. As this must be accomplished under conditions of uncertainty, probabilistic analyses are necessary in the development of such probability‐based design criteria of hull girders for surface ships. A methodology for developing load and resistance factor design (LRFD) rules for ship structures was developed in this paper, and demonstrated for surface ship hull girders.The methodology used in this paper for developing LRFD rules for ship hull girders consists of several steps as described herein. The probabilistic characteristics of strength and load random variables that are used in hull‐girder structural design were analyzed, and values for these characteristics were recommended for reliability‐based design purposes. Different load combinations for hull girders were established and presented with combinations and correlation factors that included the still water bending, wave‐induced bending, and wave dynamic bending moments.In this paper, the reliability methods for developing the partial safety factors (PSFs) for the ship hull girder in bending are described. These factors were determined to account for the uncertainties in strength and load effects. The First‐Order Reliability Method (FORM) was used to determine these factors based on prescribed probabilistic characteristic of strength and load effects. Also, strength factors were computed for a set of load factors to meet selected target reliability levels for demonstration purposes. The resulting LRFD rules are demonstrated in this paper using an example.

Improved integrated structural control design using covariance control parameterization

This paper investigates multiobjective integrated control/structure design using covariance control to parameterize the controller. An advantage of this approach is that the control objectives can be specified as a set of competing analytical goals or constraints instead of a single scalar cost function. From this formulation, a multiobjective numerical optimization problem is formulated to execute the integrated control-structure design. The performance of this approach is investigated on a simple disturbance rejection problem in which the control objectives and the structural design objectives conflict. The integrated design optimization both increases control performance and decreases the structural mass with a counterintuitive design. In addition, these results add to previous work that demonstrates the protential of integrated design optimization of structures and controllers. It then appears that when the structure and controller are considered simultaneously, the resulting combination is an improved design. However, the extent of the design improvement is apparently problem dependent.

Structural Design

The objective of Structural Design is to provide the structure that will permit the aircraft, whether military or civil, to do its job most effectively, that is with the least total effort, spread over the whole life of the aircraft from initial design until the aircraft is thrown on the scrap heap. There is thus no all-embracing simple criterion by which the success of the structural design can be judged. It is not sufficient to believe that percentage structure weight is of itself an adequate measure of effective design, either of the complete vehicle or of the structure itself; a well-known example is the provision of increased aspect ratio at the expense of structure weight, which may give increased fuel economy in the cruise and reduction in the total aircraft weight. Nevertheless, percentage structure weight is a useful measure, provided its limitations are recognised.