Developed Design Rules Research Articles

The cross-sectional resistance of square and rectangular hollow steel sections loaded by bending moment and shear force

This paper presents an evaluation of the design rules for the bending moment–shear force (M−V) interaction of cold- and hot-formed square, and rectangular hollow steel sections (SHS & RHS). More specifically, the design rules, as provided by EN1993-1-1 regarding RHS and SHS of section class 1 and 2 are covered for the steel grades S235 up to and including S460. A 4-point bending test was simulated by means of a finite element model, which was validated on the basis of experimental tests from existing literature. A parametric study was performed and numerical M−V interaction results were compared to the provisions in EN1993-1-1. This comparison indicates that the current design rules in EN1993-1-1 regarding M−V interaction are conservative and overestimate the reduction of the bending resistance due to the presence of shear. Alternative design rules for the shear area and M−V interaction of RHS and SHS are proposed and evaluated by means of a statistical assessment procedure based on existing literature and EN1990-1-1. Both newly developed design rules are shown to ensure an adequate reliability level when a partial safety factor equal to 1 is used.

Alignment of design rules for additive manufacturing and remanufacturing

Remanufacturing is one key element of a circular economy by closing the loop on the product level and thus maintaining or restoring the product design and the associated product properties. The remanufacturing process chain involves disassembly of used products, cleaning of parts, inspection and sorting of parts, reconditioning or replenishment by new parts, and product reassembly into as-new products. If new parts are required, additive manufacturing is a promising alternative to conventional manufacturing or the purchase of spare parts. Additive manufacturing is characterized by the layered or element-based construction of parts and does not require product-specific tools, enabling a cost-efficient production of individual pieces or small series. The use of specific design rules in product and process development to meet the requirements of the intended process enables and simplifies additive manufacturing or remanufacturing. Despite the design rules for additive manufacturing and remanufacturing, there are no design rules for implementing additive manufacturing technology in the remanufacturing process. In this paper, existing design rules on Design for Additive Manufacturing and Design for Remanufacturing will first be identified and compared, and possible synergies and conflicts of objectives will be analyzed. Based on this, a guideline for a Design for Additive Remanufacturing is developed to facilitate and promote the implementation of additive manufacturing in remanufacturing. The developed design rules enable the evaluation of a part aimed to be produced by additive manufacturing within the remanufacturing process and give advice on how to optimize the design of the part. This paper aims to derive general design rules for a “Design for Additive Remanufacturing” that specifically address the additive remanufacturing process.

Extension of the application limits of blind fasteners for joining high‐strength steels in metal lightweight construction

AbstractWherever joints in metal lightweight construction are only accessible from one side, joining techniques such as screwing or welding are uneconomic or inapplicable, blind fasteners and especially blind rivets as the most common type are the means of choice. Nevertheless, with the use of blind rivets, problems arise for the structural engineer, because of the lack of proper design rules according to the Eurocode 3. With the research affords of the authors this deficiency was eliminated for the field of normal strength steel in the past.However, with the increasing usage of high‐strength steels in such constructions, new problems emerge and the developed design rules are not valid yet. This paper presents results from quasi‐static tests on blind rivet joints with different steel grades of the components to extend the proposed design rules. Different effects were identified, which lead to a reduced shear resistance of the blind rivets. At the same time the results point out the benefits of high‐strength steels on the load‐bearing behaviour. Furthermore, results from fatigue tests on blind rivet joints are presented. These show a notable influence of the steel grade on the fatigue resistance of the joint as well as the potential for the design of such joints.

Enhanced sample filling and discretization in thermoplastic 2D microwell arrays using asymmetric contact angles.

Sample filling and discretization within thermoplastic 2D microwell arrays is investigated toward the development of low cost disposable microfluidics for passive sample discretization. By using a high level of contact angle asymmetry between the filling channel and microwell surfaces, a significant increase in the range of well geometries that can be successfully filled is revealed. The performance of various array designs is characterized numerically and experimentally to assess the impact of contact angle asymmetry and device geometry on sample filling and discretization, resulting in guidelines to ensure robust microwell filling and sample isolation over a wide range of well dimensions. Using the developed design rules, reliable and bubble-free sample filling and discretization is achieved in designs with critical dimensions ranging from 20 μm to 800 μm. The resulting devices are demonstrated for discretized nucleic acid amplification by performing loop-mediated isothermal amplification for the detection of the mecA gene associated with methicillin-resistant Staphylococcus aureus.

From Nano to Macro through Hierarchical Self‐Assembly: The DNA Paradigm

From atoms to molecules and bio-macromolecules, from organelles to cells, tissues, to the whole living system, nature shows us that the formation of complex systems with emergent properties originates from the hierarchical self-assembly of single components in guided bottom-up processes. By using DNA as a fundamental building block with well-known self-recognition properties, scientists have developed design rules and physical-chemical approaches for the fully programmable construction of highly organized structures with nanosized features. This review highlights the basic principles of hierarchical self-assembly in terms of type and number of distinguishable components and their interaction energies. Such general concepts are then applied to DNA-based systems. After a brief overview of the strategies used until now for the construction of individual DNA units, such as DNA tile motifs and origami structures, their self-association into assemblies of higher order is discussed. Particular emphasis is given to the forces involved in the self-assembly process, understanding and rational combination of which might help to coordinate the single elements of hierarchical structures both in space and time, thus advancing our efforts towards the creation of devices that mimic the complexity and functionality of natural systems.

On design for additive manufacturing: evaluating geometrical limitations

Purpose – The purpose of this paper is to present Design Rules for additive manufacturing and a method for their development. Design/methodology/approach – First, a process-independent method for the development of Design Rules was worked out. Therefore, geometrical standard elements and attributes that characterize the elements’ shapes have been defined. Next, the standard elements have been manufactured with different attribute values with Laser Sintering, Laser Melting and Fused Deposition Modeling, and their geometrical quality was examined. From the results, Design Rules for additive manufacturing were derived and summarized in a catalogue. Findings – Due to the process independent method, Design Rules were developed that apply for the different considered additive manufacturing technologies equally. These Design Rules are completely function-independent and easily transferable to individual part designs. Research limitations/implications – The developed Design Rules can only apply for the considered boundary conditions. To extend the Design Rules’ validity, their applicability should be proven for other boundary conditions. Practical implications – The developed Design Rules practically support the design of technical parts. Additionally they can be used for training and teaching in the field of “design for additive manufacturing”. Originality/value – The developed Design Rules constitute a first step toward general Design Rules for Additive Manufacturing. Thus, they might form a suitable basis for further scientific approaches, and the Design Rules can be used to set up teaching documentations for lessons and seminars.

Fire design rules for load bearing cold-formed steel frame walls exposed to realistic design fire curves

Light gauge Steel Frame (LSF) walls are extensively used in the building industry due to the many advantages they provide over other wall systems. Although LSF walls have been used widely, fire design of LSF walls is based on approximate prescriptive methods based on limited fire tests. Also these fire tests were conducted using the standard fire curve (ISO 834-1, 1999 [1]) and the applicability of available design rules to realistic design fire curves has not been verified. This paper investigates the accuracy of existing fire design rules in the current cold-formed steel standards and the modifications proposed by previous researchers. Of these the recently developed design rules by Gunalan and Mahendran (2013) [2] based on Eurocode 3 Part 1.3 (EN 1993-1-3, 2006 [3]) and AS/NZS 4600 (Standards Australia (SA), 2005 [4]) for standard fire exposure (ISO 834-1, 1999 [1]) were investigated in detail to determine their applicability to predict the axial compression strengths and fire resistance ratings of LSF walls exposed to realistic design fire curves. This paper also presents the fire performance results of LSF walls exposed to a range of realistic fire curves obtained using a finite element analysis based parametric study. The results from the parametric study were used to develop a simplified design method based on the critical hot flange temperature to predict the fire resistance ratings of LSF walls exposed to realistic fire curves. Finally, the stud failure times (fire resistance rating) obtained from the fire design rules and the simplified design method were compared with parametric study results for LSF walls lined with single and double plasterboards, and externally insulated with rock fibres under realistic fire curves.

Efficient excitation and control of arbitrary surface plasmon polariton beams using one-dimensional metallic gratings

We derive a general approach for efficient excitation and control of arbitrarily shaped surface plasmon polariton waves, using one-dimensional metallic gratings by tailoring the exciting beam. We present a complete and rigorous theory that relates the electromagnetic fields of the free-space beam impinging on the grating to the resulting surface plasmon. We deduce an optimal grating and efficient polarization schemes which facilitate the excitation of surface plasmons propagating at angles up to almost 90 deg with respect to the grating’s axis with negligible polarization losses. The theoretical predictions are verified both numerically and experimentally by exciting two-dimensional surface plasmons through one-dimensional metallic gratings. We show that this method can be readily applied for generating arbitrary plasmonic wave fronts, and the general design formalism is given. Finally, we show how the developed design rules can be applied for the excitation of optically controlled surface plasmon hot spots.

Design Methodology and Performance Evaluation of a Tapered Cell

Tapered cells are used in the calibration of electric field (E-field) probes. However, the design methodology of tapered cells has not been publicly reported in detail. This paper introduces the structure of a tapered cell and proposes a theoretical model for characteristic impedance calculation. Based on this model and developed design rules, an impedance-matched tapered cell was constructed. The measured characteristic impedances and impedance distribution along the cell show favorable agreement with the design goals, verifying the accuracy of the design methodology. The field distributions were also measured. The results prove that the cell is useful for calibrating E-field probes.

Design Rules for IGZO Logic Gates on Plastic Foil Enabling Operation at Bending Radii of 3.5 mm

Findings obtained from bending experiments with mechanically flexible InGaZnO-based thin-film transistors are used to derive design rules for flexible InGaZnO-based n-channel metal-oxide-semiconductor logic circuits. Based on the developed design rules, flexible NAND gates, inverters, and five-stage ring oscillators are fabricated directly on free-standing plastic foils at temperatures ≤ 150 °C. Geometrically well-designed circuits operated at a supply voltage of 5 V are exposed to tensile mechanical strains, induced by bending, up to 0.72% without performance degradation. This corresponds to a bending radius of 3.5 mm. At the same time, increases in the rise time by a factor of ca 2 and reductions in the high and low output voltage levels by ca 10% and 50% have been observed for circuits with disadvantageous geometrical design. Ring oscillators designed to be operated under strain show an increase in oscillation frequency from 22.9 kHz (flat substrate) to 23.32 kHz (bending radius: 3.5 mm). This demonstrates the held-effect mobility increase in a-IGZO-based circuits under tensile mechanical strain. Long-term reliability is evaluated with 20000 cycles of repeated bending and reflattering without circuit failure.

An annular array design proposal with multiple geometric pre-foci

An annular array design method is described and used for definition of an array proposal. The geometric pre-focus, realized by curving or use of an acoustic lens, varies among the annuli. Element sizes and geometric pre-focus depths are determined by a maximum allowed phase-shift within the active depth region of each element on receive, resulting in fewer elements or larger apertures compared with the standard equal area design. The method allows combination of large aperture and high frequency with a large receive depth of field. The developed design rules are used to define an array for imaging within the frequency interval [7.5, 15] MHz. Its total aperture diameter is 22 mm and the thinnest element is 0.23 mm wide. Receive beams resulting from this array are simulated. The beams and their sidelobe-to-mainlobe energy ratios are compared with an ideally focused reference where there are no phase shifts over the elements. Within nearly the entire depth of field, the sidelobe-to-mainlobe energy ratio is less than 5 dB higher than for the ideal reference.

Local Buckling Design Rules for Profiled Sandwich Panels Based on the Studies of Foam-Filled Steel Beams

Modern composite sandwich constructions have been used very successfully in many aerospace and structural applications. Various aspects of structural behaviour of sandwich panels have been researched for many decades as they are a potential load carrying component in buildings. Sandwich panels exhibit various types of buckling failure modes depending on the types of steel faces used. Local buckling is one of the fundamental failure modes of sandwich panels with profiled faces. To investigate the local buckling behaviour, Davies & Hakmi (1992) conducted a series of bending tests of foam-filled thin-walled steel beams and developed a design method that is now adopted in the European recommendations for the design of sandwich panels (CIB, 2000). However, recent studies by Pokharel & Mahendran (2003; 2004a; 2004b) have shown that this design method is inadequate for sandwich panels with very slender plate elements, and therefore developed a new design rule that is applicable for a wide range of width-to-thickness (b/t) ratios of foam supported plate elements. This research was undertaken to investigate the applicability of these design rules based on the results from Davies & Hakmi’s (1992) bending tests of foam-filled steel beams and a numerical study simulating the bending tests. Both the experimental and numerical results were then compared with the predictions from the current and newly developed design rules. This paper presents the details of Davies & Hakmi’s (1992) bending tests and corresponding numerical modelling, evaluation and comparison of results.

Creating Usable Wordless Instructions for Performing Complex One-Time Tasks: Effects of Violating the Rules

We have developed design rules for diagrammatic instructions for initial setup, basic maintenance and troubleshooting (i.e., clearing paper jams) tasks. The study reported here evaluated these rules. Four groups of novice users cleared paper jams in a laser printer using one of four different diagrammatic instructions. Diagrams presented to the first two groups all followed the rules but differed in the number of actions per diagram (one verses 3-4). The remaining groups' instructions contained diagrams that violated one or more rules. Instructions that followed the diagram design rules resulted in no errors. Diagrams that prevented users from correctly identifying the location of a subtask resulted in the most severe errors. Other rule violations resulted in fewer errors of lesser severity so if users were shown the general location of the problem they could perform a subtask. Times to complete each subtask were similar unless the location rule was violated.

Optical correlation of images with signal-dependent noise using constrained-modulation filter devices

Images with signal-dependent noise present challenges beyond those of images with additive white or colored signal-independent noise in terms of designing the optimal 4-ƒ correlation filter that maximizes correlation-peak signal-to-noise ratio, or combinations of correlation-peak metrics. Determining the proper design becomes more difficult when the filter is to be implemented on a constrained-modulation spatial light modulator device. The design issues involved for updatable optical filters for images with signal-dependent film-grain noise and speckle noise are examined. It is shown that although design of the optimal linear filter in the Fourier domain is impossible for images with signal-dependent noise, proper nonlinear preprocessing of the images allows the application of previously developed design rules for optimal filters to be implemented on constrained-modulation devices. Thus the nonlinear preprocessing becomes necessary for correlation in optical systems with current spatial light modulator technlogy. These results are illustrated with computer simulations of images with signal-dependent noise correlated with binary-phase-only filters and ternary-phase-amplitude filters.

Achieving the limits of IATOin TIL GTO thyristors

A rigorous developmental design has been performed with the aim of achieving the limits of the peak interruptable anode current I ATO in 4 × 4-mm area T0-220-packed two-interdigitation levels TIL GTO thyristors. The developed design rules with general validity are rooted in the peculiar operation principles of TIL GTO's and take into consideration the electrothermal failure-safety conditions usually affecting the current-handling capability of GTO's. The high-voltage TIL GTO's, fabricated according to the developed guidelines, possess a value of I ATO = 65, ..., 70 A under the heaviest possible on-state power dissipation test conditions. This value is the highest ever reported in the open literature for this class of GTO's (identical device area and case) and is determined primarily by the thermal impedance junction-to-case Z th j-c of T0-220 packages. The broad implications of obtained results are also outlined in this communication.