Practical Engineering Design Research Articles

Study of Sericite Quartz Schist Coarse-Grained Soil by Large-Scale Triaxial Shear Tests

The large-scale triaxial consolidated-drained (CD) and consolidated-undrained (CU) shear tests were carried out to investigate performances of the sericite quartz schist coarse-grained soil on stress-strain, deformation, and strength under four different confining pressure conditions. The test results indicated that the stress-strain curve of sericite quartz schist was nonlinearity, compressive hardening and elastic-plastic. The shear strength envelope curve was better. In the triaxial CD shear test, the sericite quartz schist exhibited weak strain softening under different confining pressures. The sample showed shearing shrinkage at first and later dilatancy under confining pressures of 200, 400, and 600 kPa. When the confining pressure was 800 kPa, the sample showed a trend of shearing shrinkage. In the triaxial CU shear test, the sericite quartz schist exhibited strain hardening, presenting a tendency of shearing shrinkage at first and later dilatancy. It is more reasonable to take account of the cohesion of sericite quartz schist in practical engineering design by linear-regression analysis.

Investigation of hydrodynamics in high solid anaerobic digestion by particle image velocimetry and computational fluid dynamics: Role of mixing on flow field and dead zone reduction

High solid anaerobic digestion (HSAD) was a potential organic waste treatment. Compared with low solid anaerobic digestion, it had the advantages of small footprint, less digestate, and low heating energy. However, HSAD’s methane production is poor, mainly due to the complex hydrodynamics. In this study, computational fluid dynamics were utilized for HSAD’s hydrodynamics investigation at 14.3% solid content and compared to the particle image velocimetry measurement. Then, effects of mixing on hydrodynamics were investigated. The results indicated that the diameter of impeller was critical for the radial mixing, and the distance between the impellers dictated the axial mixing. Besides, rotating speed affected flow velocities significantly, but displayed less effect on expanding the mixing range. Furthermore, HSAD’s treating capacity could be increased at large extent by optimizing mixing. The visualization of the hydrodynamics in this study could potentially offer conceptual basis for HSAD’s design in practical engineering.

A Study on Axial Compression Performance of Concrete-Filled Steel-Tubular Shear Wall with a Multi-Cavity T-Shaped Cross-Section

In order to study the axial compression performance of the T-shaped multi-cavity concrete-filled steel tube shear wall, first, three specimens were designed to perform the axial compression test. Then three-dimensional finite element analysis by the ABAQUS software was used to obtain the axial bearing capacity of the shear wall with different parameters. According to the results of the finite element model, the computational diagram in the limit state was obtained. The diagram was simplified into the core concrete in the non-enhanced area that was not constrained by the steel tube and the core concrete in the enhanced area that was uniformly constrained by the steel tube. Finally, a new practical equation for calculating the axial bearing capacity of a multi-cavity concrete-filled steel tubular shear wall was deduced and proposed based on the theory of ultimate equilibrium. The calculation results of the proposed equation were in good agreement with the finite element results, and the proposed equation can be used in practical engineering design.

Dynamic response of an embedded flexible foundation of general shape in a transversely isotropic and multilayered half-space

A new semi-analytical method is developed for solving the dynamic response of an embedded flexible foundation of general shape in a transversely isotropic and multilayered half-space. It is based on the hybrid Green's functions (GFs) and finite-element method (FEM) via the modified subtraction method. The GFs in the multilayered half-space are derived by virtue of the dual variable and position (DVP) method whilst the FEM is utilized to discretize the domain of the embedded foundation. Making use of the modified subtraction method, the GFs and FEM formulations are combined to derive the dynamic impedance matrix of the embedded foundation. After verifying the accuracy and stability of the proposed algorithm, numerical studies are carried out to investigate the effect of the foundation modulus, half-space anisotropy, and layering on the dynamic impedance matrix of the embedded foundation. Results show that these factors could significantly affect the dynamic impedance matrix of the foundation, which could provide reference for practical engineering design.

Assessment of tunnel face stability subjected to an adjacent tunnel

This paper conducts a reliability assessment of the tunnel face stability induced by an adjacent tunnel under incomplete information. The evaluation indicator in this study is the limit support pressure (LSP) for the tunnel excavation face, which is first determined through a detailed finite element analysis. Relying on the numerical results, a hybrid particle swarm optimization-neural network (PSO-NN) is developed to construct the meta-model for LSP. This study develops a framework of Monte Carlo simulation combing with the trivariate copula analysis of the cohesive strength, Poisson ratio, and internal friction angle, to assess the probability distribution of LSP with incomplete information. This study proposes an index α greater than 1.0, to quantify the copula's effect in forty-six illustrative cases. Finally, this paper examines the reliability of different existing formulas of LSP in the tunneling excavation procedure. Rankine and Terzaghi's formulas show a higher reliability value above 0.8. Furthermore, this study proposes a new safety factor for engineering design considering the uncertainties and copula's effect. Through further examining the performance of the new safety factor based on the Rankine and Terzaghi approaches, this study proposes a new procedure to determine LSP for a safe and efficient engineering design practice.

A model validation framework based on parameter calibration under aleatory and epistemic uncertainty

Model validation methods have been widely used in engineering design to evaluate the accuracy and reliability of simulation models with uncertain inputs. Most of the existing validation methods for aleatory and epistemic uncertainty are based on the Bayesian theorem, which needs a vast number of data to update the posterior distribution of the model parameter. However, when a single simulation is time-consuming, the required simulation cost for the validation of a simulation model may be unaffordable. To overcome this difficulty, a new model validation framework based on parameter calibration under aleatory and epistemic uncertainty is proposed. In the proposed method, a stochastic kriging model is constructed to predict the validity of the candidate simulation model under different uncertainty input parameters. Then, an optimization problem is defined to calibrate the epistemic uncertainty parameters to minimize the discrepancy between the simulation model and the experimental model. K–S test finally decides whether to accept or reject the calibrated simulation model. The performance of the proposed approach is illustrated through a cantilever beam example and a turbine blade validation problem. Results show that the proposed framework can identify the most appropriate parameters to calibrate the simulation model and provide a correct judgment about the validity of the candidate model, which is useful for the validation of simulation models in practical engineering design.

Technical Sentiment Analysis. Measuring Advantages and Drawbacks of New Products Using Social Media

The paper contributes to the literature on sentiment analysis by introducing a new knowledge-based lexicon. The lexicon, based on fundamental research and systematic practice in Engineering Design, describes the Advantages or Drawbacks (Disadvantages) of products as an effect of the interaction between artifacts and users. The paper extracts data from Twitter that report consumer conversations after the launch of new products in the videogame industry. It compares the results of a traditional sentiment analysis with the results filtered using the lexicon. We observe a drop in the number of positive tweets but a sharp increase in the informativeness of consumers’ opinions. Comments filtered using the lexicon offer a much more useful basis for understanding customers and designing new products. The paper develops several areas of potential applicability of the methodology.

An adaptive sampling method for Kriging surrogate model with multiple outputs

The sample distribution has a vital influence on the quality of a Kriging surrogate model, which may further influence the required cost or convergence of the surrogate model-based design and optimization problems. Adaptive sampling methods utilize the information from existing samples to reasonably allocate the sequential samples, which can generally build a more accurate Kriging surrogate model under the same computational budget. However, most of the existing adaptive sampling methods for the Kriging surrogate model are only available for single-output problems, and there are few studies on problems with multiple responses. In this paper, an adaptive sampling method based on Delaunay triangulation and technique for order preference by similarity to ideal solution (TOPSIS) is proposed for Kriging surrogate model with multiple outputs (mKMDT). In the proposed mKMDT, Delaunay triangulation is used to partition the design space into multiple triangle regions, whose area denotes the dispersion of the sample points. The prediction error at each triangle’s centroid represents the local approximation error. Specifically, three different strategies are developed when allocating weights to the area and the prediction error of each triangle with the entropy method and the TOPSIS method. The performance of the proposed method is illustrated through numerical examples with different numbers of outputs and a collision problem between the missile and the adapter. Results show that the proposed method can construct an accuracy surrogate model with few samples, which is useful for practical engineering design problems with multiple outputs.

Optimisation of a novel, sloped module, multibody wave energy converter, using an efficient modelling technique

Whilst energy can be efficiently extracted from waves by a device exhibiting sloped motion, sustaining that performance in a deep water environment would conventionally rely on a costly support structure. Introduced herein, the WaveTrain device provides an alternative approach to retain the benefits of sloped motion, using a series of joints and struts to mechanically interconnect a series of sloped modules, each of which houses an internal water column to allow reaction against the surrounding water inertia. With a view to maximal power extraction in a real wave climate, this paper presents an optimisation of key parameters associated with the geometry and mass distribution. This relies upon an efficient hydrodynamic model, whose development is presented, particularly with respect to the use of ‘generalised’ modes to model hinges, for which a somewhat didactic treatment is given. A genetic algorithm, tailored specifically to handle the discontinuous parameter space and the numerical hydrodynamic model, is then used to identify design criteria that are essential for optimal power extraction. Five necessary but not sufficient criteria are presented, in addition to guidance regarding the remaining parameters, which is used to briefly highlight the potential benefits for the practical engineering design.

Experimental study and numerical simulation on dynamic soil‐structure interaction under earthquake excitations

Soil-structure interaction (SSI) phenomena subjected to seismic loadings are investigated in this study. Firstly, shaking table tests on dynamic soil‐structure interaction subjected to seismic loadings are carried out, and SSI effects are analyzed through a comparative study between the soil-structure system and the rigid foundation condition. Then, a corresponding numerical model on the SSI tests is presented. In the finite element model, a bounding surface plasticity model and an equivalent linear method are separately used for simulating the nonlinear behavior of soil. It turns out that the calculated results by the bounding surface plasticity model agree much better with the experimental results. Finally, the effects of different soil types and structural properties on soil-structure interaction are discussed by numerical parametric study. The results show that SSI effects noticeably mitigate the dynamic response of structure, and the closer the frequency of superstructure to the soil frequency, the more obvious the effect of soil-structure interaction. With increased shear wave velocity of soil, the impact of soil-structure interaction weakens. It is important for studying the impact of SSI on structural responses and practical engineering design purposes.

Critical Velocity of Short Floating Slab Track Using Alterable Element Method Considering Wheel-Rail Contact Loss

In actual line operation, the critical velocity is one of the key physical quantities of rail design owing to its great influence on the riding comfort and safety of vehicles due to the wheel-rail contact loss caused by the abrupt change of rail foundation rigidity, rail wear, or abruptness irregularities on rail. In this study, the short floating slab track (SFST) structure is regarded as a double-layer system. The Euler beam and the rigid body model are adopted for the rail and the floating slab, respectively, and the dispersion equation and the theoretical critical velocity of the rail structure under ideal conditions are deduced. Besides, this study considers the implementation of the SFST in the vehicle-structure coupling system. The alterable element method is introduced for accurately simulating the change of the wheel-rail contact state and coding a vehicle-structure dynamic analysis program (VSDAP) to calculate the critical velocity of rail structures from the dynamic response of vehicles and rail structures. The principle of its design at the beginning of the design is given on the basis of the theoretical value of the critical velocity and the simulation of the dynamic response, which can provide reference for practical engineering design.

Design space exploration and optimization using self-organizing maps

Identifying regions of interest (RoI) in the design space is extremely useful while building metamodels with limited computational budget. Self-organizing maps (SOM) are used as a visualization technique for design space exploration that permits identifying RoI. Conventional implementation of SOM is susceptible to folds or intersections that hinder visualizing the design space. This work proposes a modified SOM algorithm whose maps are interpretable and that does not fold and allows smoother input and performance space visualization. The modified algorithm enables identification of RoI and additional sampling in the identified RoI allows building accurate Kriging metamodel, which is then used for optimization. The proposed approach is demonstrated on benchmark nonlinear analytical examples and two practical engineering design examples. Results show that the proposed approach is highly efficient in identifying the RoI and in obtaining the optima with less samples.

Research on Structural Design of Coal Crusher House in Thermal Power Plant

This paper takes the specific characteristics of pulverized coal room in thermal power plant as the starting point，firstly, this paper analyzes the process layout and structure selection, and then the structural design and vibration design requirements of coal crusher house are introduced in this paper. Finally, based on the engineering example, a new structure form of vibration isolation design is creatively proposed, which provides a new design idea for the practical engineering design

Orthogonal Optimization Design of Scour Protection Device with Flexible Material for Pile Foundation

To apply the scour protection device with the flexible material developed by the author to engineering practice, orthogonal optimization design of the device for a fixed offshore platform in Chengdao Oilfield as a case study was presented. The influences of main design parameters, such as pile diameter, thickness of flexible material and elastic modulus of flexible material on the protective effect of the device were studied by two-way fluid-solid interaction numerical simulation based on ANSYS workbench platform. Then, the optimal design plan of the scour protection device with flexible material was determined. Furthermore, by comparing and contrasting the results of the flow field calculation for the pile legs with versus without protective devices were compared and analysed, the device’s good effective protection effect functionality was demonstrated. The research results will shed light on the practical engineering design of the flexible energy dissipation guiding antiscour device.

Industry Survey for Determining the State of Practice of Front End Engineering Design for Industrial Construction

AbstractPlanning work conducted early during a construction project, known as front end planning (FEP), has a large impact on project outcomes and significant influence on the configuration of the ...

Crashworthiness design of graded cellular materials: An asymptotic solution considering loading rate sensitivity

Introducing graded cellular materials into energy absorber may improve the crashworthiness of protective structures. In order to meet the crashworthiness requirement that the impact force does not exceed the value that the protected object can afford, a backward strategy guiding the design of relative density distribution of cellular material is improved by considering the loading rate sensitivity in a shock model. Asymptotic solutions of the relative density distribution are obtained for the cases with or without considering the loading rate sensitivity, when a constant impact force is required. It is found that the second-order approximate solutions of the relative density distribution are good enough to approximate the exact solutions calculated by the fourth-order Runge-Kutta scheme. The validity of the design method is further verified by the cell-based finite element method, and the results indicate that the deformation localization at the proximal end is caused by both the density gradient and inertial effect. It is shown that the average impact force from the design without considering loading rate sensitivity exceeds the affordable value of the protected object, but that considering loading rate sensitivity can well meet the crashworthiness requirement. Therefore, the asymptotic solution of the relative density distribution from the design strategy considering loading rate sensitivity is suitable and convenient to guide the crashworthiness design in practical engineering.

Mechanical behavior of buried composite pipelines subjected to strike-slip fault movement

Buried composite pipelines crossing active faults can be deformed significantly due to strike-slip fault movement. Because of the problem complexity arising from material mechanical behavior and imposed large deformation, a numerical analysis was conducted using a nonlinear finite element approach. The lateral displacement incrementally was imposed normal to the pipe axis until one of the pipe layers failed based on the Hashin failure criteria. The effective factors on the buried composite pipeline performance, such as the pipe dimensions, composite lay-up, and soil stiffness, were studied parametrically. The results showed that the winding angle of the composite pipe has significant effects on the response of the pipe subjected to the fault movement, therefore determining an optimum winding angle is very important for practical engineering designs. In addition, the results show that the effect of changing the pipe diameter cannot be predicted easily, and also it is depended on the winding angle. However, changing the soil stiffness did not change the optimum winding angle. Furthermore, the comparison conducted for the studied composite and steel pipes at the similar simulation conditions showed that the composite pipe has a better response until the onset of the failure, and the composite pipe could be considered as a suitable replacement for the conventional buried steel pipeline.

Assessing fire frequency and structural fire behaviour of England statistics according to BS PD 7974-7

Contemporary structural fire statistics are fundamental in engineering design practice to evaluate likelihood and consequence of fire for different property types, and to investigate how different safety measures impact fire spread. British Standard PD 7974-7:2003 has recently been updated using USA fire statistics; this paper compares PD 7974-7:2003 to current England statistics (named UK statistics) using one public and one Home Office dataset. PD 7974-7:2003 overestimates fire frequency with values up to 5 times greater than the ones found in UK and USA. When fire frequency is plotted against total floor space, for different property types, power laws with positive or negative exponent and polynomial functions provide better approximations of the data than the current codes. Average area damage from PD 7974-7:2003 has been compared to fire and total damage from UK datasets where fire size is usually well confined to room of origin at 20% of fires based on the publicly available dataset. When fires exceeding specific areas of damage are considered, PD 7974-7:2003 usually overestimates fire damage and underestimates total damage, with more damage evident when sprinklers are absent compared to when they are present.

Compressive strength of axially loaded circular concrete-filled double-skin steel tubular short columns

The confinement effect of external and internal steel tubes on sandwiched concrete in concrete-filled double-skin circular steel tubular (CFDST) short columns has a significant impact on the compressive strength and ductility of columns. Limited researches on CFDST columns have only considered the influences of a part of column parameters on the confinement effect, leading to the absence of appropriate compressive strength formulas in international standards. To comprehend the compressive behavior of circular CFDST short columns and suitably evaluate their compressive strength for practical engineering design, it is necessary to further launch the experiments on circular CFDST short columns and develop a suitable estimated formula for their compressive strength. The purpose of this paper is to develop a simple and accurate formula for predicting the compressive strength of axially loaded CFDST short circular columns with a wide range of parameters. A total of 24 specimens with outer and inner circular carbon steel tubes that withstand axial compression were tested. A new confinement coefficient reflecting the confinement effect of concrete strength in CFDST columns was proposed on the basis of the test data in the present paper and data collected from literature. Utilizing the proposed confinement coefficient, a novel strength design formula was developed to estimate the compressive strength of CFDST short circular columns. It shows that the proposed confinement coefficient can reasonably reflect the interaction effect between the sandwiched concrete and steel tubes, and the formula suggested in this paper offers better predictions of the compressive strength than current design formulas.

IDENTIFYING REASONS FOR A LACK OF METHOD APPLICATION IN ENGINEERING DESIGN PRACTICE – AN INTERVIEW STUDY

AbstractDesign methods are seldom used in engineering design practice. The presented study aims at finding the alternative strategies for situations with a need for methodological support. Semi-structured interviews were conducted with ten experienced design engineers to identify causes of and strategies for those situations. Three strategy clusters could be identified: generating information, experience and method application. As the individual's and the team's experience compete with the application of methods, they are seen as reasons for a lack of method application.