Support Layout Research Articles

Designing Intelligent Rock Support Systems to Detect Gravity-Driven Wedges

AbstractIntelligent rock bolts can be used in mining operations to acquire information on the bolt's status and movements of the rock mass. The future value of this technology resides in optimizing the support layout and increasing safety. The primary goal of this research is to investigate the sensor spatial distribution necessary for efficiently identifying roof wedges in mines. Roof wedges occur when three joints intersect over the roof, forming a triangular shape. They present a hazard by falling and causing damage. Sensor density refers to the number of sensors on a single rock bolt and the number of intelligent rock bolts in the mine or one section. Too many sensors drive costs up, and too few sensors compromise measurement quality. This research visualizes and investigates the results of the simulated models of intelligent rock bolts depending on the number of installed sensors and intelligent bolts to get a better understanding of the problem and describe the technique used, including numerical simulations and the considered parameters. Furthermore, it offers insight into the findings' possible implications, providing knowledge about the viability of using intelligent rock bolts.

Dynamics modelling and Layout optimization of CFRP in-situ machining system

The multi-support reconfigurable compliant tooling and robotic in-situ processing method provide a new technical direction for CFRP milling edge processing. Aiming at the layout optimization of CFRP in-situ machining system (CFRPIMS), the dynamics characteristics of the whole system were studied. A rigid-flexible coupling dynamics model of the CFRPIMS was proposed by applying transfer matrix method for multibody systems (MSTMM), treating CFRP as a thin-walled flexible plate and supporting fixtures as rigid bodies. And then the natural frequency and dynamics responses under the different support layout are simulated, which are verified by modal tests and excitation tests. To improve the support rigidity of CFRP workpieces, the optimization model of overall layout of the compliant tooling was established combined with genetic algorithm. Based on the milling test results, compared with the original scheme, the optimization method can effectively reduce the vibration response of the workpiece in the y-direction (along the milling edge direction) and the z-direction (perpendicular to milling edge direction) by more than 60 %.

Natural frequency assignment of a pipeline through structural modification in layout optimization of elastic supports

Layout optimization of elastic supports is an effective approach to address the resonance problem of an industrial post-manufactured pipeline. However, previous investigations of support layout optimization of a post-manufactured pipeline usually require establishing or updating the numerical model of the whole pipeline system, which may lead to time-consuming calculations and poor optimization results. In order to overcome these drawbacks, a new measurement-based layout optimization method is proposed in this method. Only a small number of experimental modal parameters (natural frequencies, damping ratios, and mode shapes) are needed in this method. Resonance avoidance, in this method, is recast as an assignment of natural frequencies, and the target natural frequencies are realized by performing structural modification in two stages. In addition, each of the elastic supports is viewed as a mass-spring-damper sub-system in this paper, which is represented by its measured dynamic stiffness and does not need a pre-determined simplified form. A numerical example demonstrates that the proposed method can accurately realize the target natural frequencies. The application of the proposed method to optimize the support layout of a real L-shaped pipeline system provides experimental evidence of its effectiveness. This experiment is the first attempt to achieve the layout optimization of pipeline supports for solving the resonance problem of a post-manufacture pipeline, entirely relying on the measured modal data.

Research on Deformation Law of Deep Foundation Pit of Station in Core Region of Saturated Soft Loess Based on Monitoring

Saturated soft loess has a large pore structure, high compressibility, low strength, fluid plastic state, and poor engineering properties. It is still one of the key problems that engineering needs to solve. In order to study the influence of deep foundation pit excavation in the saturated soft loess area on the deformation of foundation pits, the deformation laws of ground settlement, enclosure structure, and supporting axial force were clarified based on the field tests on the deformation characteristics of deep foundation pits in areas with the high‐water level in saturated soft loess, combined with geological conditions and on‐site construction procedures. The results indicate the following: water supply and construction process were found to be the main factor in changing the surface settlement curve of deep foundation pits in saturated soft loess; increasing the construction speed of the pit bottom floor, inverted braces, floor frame beams, and sidewall frame beams to close the structure, which is conducive to restraining the deformation of the continuous underground wall and foundation pits in similar areas. In the initial stage of support layout, the axial force of steel support tends to increase too fast or even exceed the standard control value. Therefore, a reasonable preadding axial force is an effective means to control the deformation of the continuous underground wall and the axial force of the steel support. The current research results may provide a reference for constructing deep foundation pits in similar areas.

Enabling Cost-Based Support Structure Optimization in Laser Powder Bed Fusion of Metals

Support structures are essential to laser powder bed fusion (PBF-LB/M). They sustain overhangs, prevent distortion, and dissipate process-induced heat. Their removal after manufacturing is required, though, increasing the overall costs. Therefore, optimization is important to increase the economic efficiency of PBF-LB/M. To enable optimization focused on the support structures’ costs, a cost model is developed. The whole production process, including the design, manufacturing, and post-processing of a part, is considered by deriving formulas for the individual costs. The cost model is applied to a previously developed benchmark procedure. Additionally, a case study investigating different support layout strategies is conducted.

A Review on experimental and numerical studies of Glass Fibre Reinforced Polymer (GFRP) strips strengthened Reinforced Concrete (RC) slab subjected to low velocity impact

This paper reviewed the previous research on experimental and numerical studies on the impact behaviour of fibre reinforced polymer (FRP) strips reinforced concrete (RC) slab with various (FRP) strips arrangement. This review focusses on the effect of thicknesses, arrangements of FRP strips and type of support layouts. Initially, a throughout investigation was made on the FRP and its properties. Experiments associated to impact resistance of RC slabs was also performed. Furthermore, numerous finite element model (FEM) of RC slabs externally strengthened with different arrangement FRP strips were developed with ABAQUS and ANSYS. The numerical simulations on impact resistance of RC slab models externally strengthened with different arrangement FRP strips were performed. Generally, the experimental results displayed the diagonal two-way arrangement FRP strips externally bonded on bottom surface of RC slabs and four hinge supports applied had improved the impact strength significantly. The experimental and numerical impact results obtained for RC slabs externally strengthened with FRP strips were better as compared to the control RC slabs without FRP strengthening. Afterwards, the results gained from numerical was validated with experimental results. Finally, the methods and results of experimental and numerical reviewed was reliable as a reference for the study of RC slab externally strengthened with GFRP strips subjected to low velocity impact.

Impact response of novel layered two stage fibrous composite slabs with different support type

The performance of novel Layered Two Stage Fibrous Composite slabs (LTSFC) was pioneered under falling mass collisions using a combined experimental and numerical study. Such LTSFC slabs consist of three layers with and without the insertion of glass fibre mesh between the layers. LTSFC techniques were used to fabricate the composite slabs with three layers including 3%, 1.5%, and 3% of fibre content for the top, middle, and bottom layers respectively. Sixteen MLPAFC square slabs were cast with only short hooked end fibres and tested under falling mass collisions by amending two parameters namely the type of support (fixed and hinge) and support layout. Two distinct support layouts on two types of support were considered and tested with and without the glass fibre mesh between layers of LTSFC. A glass fibre mesh was introduced between the three layers to block crack growth propagation and absorb additional collision energy. The glass fibre mesh insertion between the layers and the LTSFC production technique were considered as novel modifications. A numerical study using Auto desk Fusion 360 was conducted and compared with experimental results. The numerical results showed fair agreement with the experimental test results. Based on the validated numerical models, collision energy and cracking pattern evolution were studied. The findings indicated that the glass fibre mesh insertion between the layers combined with steel fibres disrupted crack proliferation, thus exhibiting superior engrossed collision energy and postponing crack growth. Additionally, the engrossed collision energy at crack initiation and ultimate crack for the slabs with four sides fixed and hinged support were greater with respect to two opposite sides fixed and hinged support. Numerical values were in reasonable agreement with the experimental values in terms of collision energy and cracking patterns.

Experimental and numerical investigation of impact behavior of reinforced concrete slab with different support conditions

AbstractReinforced concrete (RC) slabs may be subjected to impulsive dynamic loads such as blast and impact during their service period. Many studies related to the impact behavior of RC slabs have been presented. However, comprehensive studies where the effect of the support conditions on the impact behavior of RC slabs has been investigated are still limited. Thus, this study has focused on the effects of the support types and the support layouts on the dynamic responses and the failure modes of RC slabs subjected to impact loads. In the first part of the study, 9 two‐way RC slabs with various support layouts composed of fixed and hinged supports were tested under impact load via the drop‐weight test setup. Two different input impact energies were transmitted to RC slabs during impact loading. The time histories of the accelerations and displacements occurred in RC slabs, and the impact loads acting on RC slabs were recorded. The crack patterns due to the impact load were observed. The dynamic responses obtained by experiments have been interpreted in detail. In the second part, a detailed finite element procedure in which explicit dynamic analysis is performed has been introduced for verification of the experimental results. Good agreement between the experimental and the numerical results has been demonstrated. It has been concluded that proposed finite element procedures can be used for evaluation of the dynamic responses and failure modes of RC slabs under low‐velocity impact load.

Design of Load-Bearing Systems for Open-Ended Downstream Reuse

This paper discusses the design of load-bearing systems for buildings with regard to their current lack of open-ended reusability. The reason for dismantling load-bearing systems today tends to be less related to material degradation than to a loss of functional fit with an evolving building program. It can therefore be expected that load-bearing components are reused in other systems, which extends their service life and avoids the manufacture of other components. Common design strategies to ensure the actual reusability of components consist in guaranteeing that the assembly is durable, versatile, modular, reversible, and adaptable. This paper (a) reviews these features, (b) illustrates by means of case studies that, without minimum threshold, they do not guarantee the repurpose of components into different, unforeseen systems, and (c) describes opportunities and challenges related to the design of more open-ended sets of load-bearing elements, i.e. sets whose element types allow for a substantially large number of diverse assemblies, in terms of floor plans, spans, loads, support layouts, connection types, architectural language, and integration with other building systems.

Integrated component-support topology optimization for additive manufacturing with post-machining

PurposeThe purpose of this paper is to communicate a method to perform simultaneous topology optimization of component and support structures considering typical metal additive manufacturing (AM) restrictions and post-print machining requirements.Design/methodology/approachAn integrated topology optimization is proposed using two density fields: one describing the design and another defining the support layout. Using a simplified AM process model, critical overhang angle restrictions are imposed on the design. Through additional load cases and constraints, sufficient stiffness against subtractive machining loads is enforced. In addition, a way to handle non-design regions in an AM setting is introduced.FindingsThe proposed approach is found to be effective in producing printable optimized geometries with adequate stiffness against machining loads. It is shown that post-machining requirements can affect optimal support structure layout.Research limitations/implicationsThis study uses a simplified AM process model based on geometrical characteristics. A challenge remains to integrate more detailed physical AM process models to have direct control of stress, distortion and overheating.Practical implicationsThe presented method can accelerate and enhance the design of high performance parts for AM. The consideration of post-print aspects is expected to reduce the need for design adjustments after optimization.Originality/valueThe developed method is the first to combine AM printability and machining loads in a single topology optimization process. The formulation is general and can be applied to a wide range of performance and manufacturability requirements.

Combined optimization of part topology, support structure layout and build orientation for additive manufacturing

Additive manufacturing (AM) enables the fabrication of parts of unprecedented complexity. Dedicated topology optimization approaches, that account for specific AM restrictions, are instrumental in fully exploiting this capability. In popular powder-bed-based AM processes, the critical overhang angle of downward facing surfaces limits printability of parts. This can be addressed by changing build orientation, part adaptation, or addition of sacrificial support structures. Thus far, each of these measures have been studied separately and applied sequentially, which leads to suboptimal solutions or excessive computation cost. This paper presents and studies, based on 2D test problems, an approach enabling simultaneous optimization of part geometry, support layout and build orientation. This allows designers to find a rational tradeoff between manufacturing cost and part performance. The relative computational cost of the approach is modest, and in numerical tests it consistently obtains high quality solutions.

Model Tests Investigating Spatial Tensile Behavior of Simulated Geosynthetic Reinforcement Material over Rigid Supports

AbstractA special device was designed, manufactured, and used to create a three-dimensional (3D) layout of rigid supports to investigate the spatial tensile behavior of the geosynthetic reinforceme...

Control system designing for correcting wing–fuselage assembly deformation of a large aircraft

PurposeIn aircraft wing–fuselage assembly, the distributed multi-point support layout of positioners causes fuselage to deform under gravity load, leading to assembly difficulty and assembly stress. This paper aims to propose a hybrid force position control method to balance aerodynamic shape accuracy and deformation of assembly area, thereby correcting assembly deformation and reducing assembly stress.Design/methodology/approachForce and position control axes of positioners are selected based on screw theory and ellipsoid method. The position-control axes follow the posture trajectory to align the fuselage posture. To exert force on the fuselage and correct the deformations, the force-control axes follow the contact force derived by using orthogonal experiments and partial least squares regression (PLSR). Finite element simulation and one-dimension deformation correction experiment are conducted to verify the validity of this method.FindingsSimulation results indicate that hybrid force position control method can correct assembly deformation and improve the wing–fuselage assembly quality significantly. Experiment on specimen verifies the effect of this method indirectly.Originality/valueThe proposed method gives a solution to solve the deformation problem during aircraft wing-fuselage assembly, thereby reducing assembly stress and improving assembly quality.

An optimisation design method for cryogenic pipe support layout of LNG-Powered ships

ABSTRACTFor LNG-Powered ships, cryogenic pipe bears ultralow temperature load; the stress of LNG pipe is very sensitive to the layout of pipe supports. In order to improve the safety of LNG pipe under complex loads, an optimisation design method for cryogenic pipe support layout (ODMCPSL) of LNG-Powered ships is proposed in this paper. The objective of ODMCPSL is to deduce the structure stress, and both the pipe supports number and their positions are taken as variables. An improved genetic algorithm named Genetic Assimilation–Genetic Algorithm (GA–GA) is adopted in ODMCPSL, in which a new factor named magnetic factor (MF) is introduced in mutation operation and the number of pipe supports is optimised by MF. In the algorithm, the number and positions of the pipe supports can be optimised at the same time. ODMCPSL is applied to a dual-fuel harbour tug, and the maximum stress of the LNG pipe is significantly decreased by the optimisation of pipe supports. The engineering application example proves that ODMCPSL has high convergence and efficiency.

Low velocity impact behavior of RC slabs with different support types

Studies focused on the effects of supporting conditions on the behavior of reinforced concrete slabs subjected to static and dynamic loadings may be found in the literature. However, in the literature no study was found about the effect of variation of the support conditions on the behavior of slabs subjected to impact loads. Consequently, an experimental study was performed on the behavior of reinforced concrete slabs subjected to impact loading. Eight (8) square reinforced concrete slabs with dimensions 500×500×50mm were tested by changing two parameters; (i) support type, (ii) support layout. In scope of the experimental study, 4 different support layouts were considered on 2 main support types (i.e. fixed and hinge supports). In the experimental study, impact loadings were applied to the specimens using a drop weight impact test set up. Acceleration-time responses of those specimens were measured by dropping a standard-weighing hammer from a height of 500mm. Effects of the parameters on the damage distribution, number of drops, acceleration-time, velocity-time and displacement-time responses were investigated. Variations of velocities and displacements were calculated for all specimens by using measured accelerations. Finite element analyses conducted using ANSYS Explicit STR software was used to simulate the experiments. It was observed that the results obtained using the numerical model was in good agreement with those obtained from the experimental study.

Multi load-transmitting device based support layout optimization for large fuselage panels in digital assembly

A large fuselage panel is always connected to a full-scale shape-preserving bracket to enhance its stiffness in digital assembly processes and reduce assembly deformation induced by factors such as gravity. However, the full-scale shape-preserving bracket’s characteristics, such as large size and weight, usually result in a complex installation process and high maintenance costs. A method for optimizing a multi load-transmitting device based discrete support layout is presented in this paper. By constructing finite element model including the fuselage panel and LTDs, the panel’s strain energy under different support layout parameters is obtained according to the principle of mixed uniform design. Using the method of partial least squares regression, the mathematical relationship between the strain energy and the support layout parameters is established, which is then used to obtain the optimum multi LTD based support layout. Furthermore, by comparing the panel deformation under the optimum multi LTD based support with that under the full-scale shape-preserving bracket-based support, we conclude that the optimum multi LTD based support can not only suppress panel deformation effectively, but also keep the panel’s stiffness comparable to that under the full-scale shape-preserving bracket-based support.

A review of Computational Modelling of Additive Layer Manufacturing - multi-scale and multi-physics

This paper presents a review of the state-of-the-art in computational modelling of the Additive Layer Manufacturing (ALM) process, with a description and examples of models being developed at Swansea University, and a comparison to efforts from other commercial and academic organisations. As a process, ALM is strongly based on computational control and the production of net- shape parts, computational modelling is being used to understand and improve the process, as well as to create new and optimised functionality of components. Modelling efforts range from discrete element models of powder flow, to micro-and macro- scale models of the laser melt-pool, coupled thermal-structural models to predict residual stress, and automated optimisation methods for the development of new components. Modelling can also be used at a microstructural level for the prediction of the bulk properties. In all instances, the modelling is used with the purpose of increasing understanding to address known problems of the ALM process. Thus, as examples, residual stresses arise in metallic parts due to the requirement of building each layer from a base-plate with supports, and modelling can help reduce and optimise the support layout to produce as-built parts with minimal residual stress for maximum strength and minimum distortion. Understanding the heat transfer at the level of the melt-pool helps to reduce porosity and gas entrainment, as well as control the local heating rates which affect the formation of balling, which has been linked to surface roughness and also to porosity. If one looks at the evolution of computational models for casting as an indication of the way in which computation of modelling of ALM could be going, one of the long-term, but most highly coveted achievements would be a full process model, which allows the integration of micro- and macro-models of the process, with life-time component property prediction and the capability of simulating design and manufacturing iterations for a final component with optimised functionality.

Optimum geometric layout of a single cable road

Cable-based technologies have been a backbone for harvesting on steep slopes. The layout of a single cable road is challenging because one must identify intermediate support locations and heights that guarantee structural safety and operational efficiency while minimizing set-up and dismantling costs. Our study objectives were to (1) develop an optimization approach for designing the best possible intermediate support layout for a given ground profile, (2) compare optimization procedures between linearized and nonlinear analyses of a cable structure and (3) investigate the effect of simplifying a multi-span representation. Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions. Those nonlinear assumptions also stipulate lower heights for intermediate supports and a larger span length. Finally, compared with the unloaded case, tensile force in the skyline is increased by as much as 80% under load for a single-span skyline configuration. Our approach provides additional value for cable operations because it ensures greater structural safety at a lower cost for installation. Improvements are still needed in developing a stand-alone application that can be easily distributed. Moreover, our rather simple assumptions regarding set-up and dismantling costs must be refined.

Twenty years of evolution for the DORIS permanent network: from its initial deployment to its renovation

The ground network is one of the major components of the DORIS system. Its deployment, managed by the French national mapping agency [Institut Geographique National, (IGN)], started in 1986 at a sustained pace that allowed it to reach 32 stations upon the launch of the first DORIS-equipped satellite (SPOT-2) in 1990. For the first generation of transmitting antennas, the installation procedures were adapted to the decimetre performance objective for the DORIS system. During the second era of the deployment of an even denser network, the antenna support layouts gradually evolved towards a better quality, thus improving the long-term stability of the antenna reference point, and a new antenna model allowed a more accurate survey. As the positioning accuracy of the DORIS system improved, it was necessary to review the antenna stability for the whole network. A first stability estimation, using criteria like antenna model and support design, was followed by a major renovation effort which started in 2000 and is now almost complete. In 6 years, through the renovation or installation of 43 stations and the implementation of new installation procedures to meet more stringent stability requirements, significant improvement in network quality was achieved. Later a more analytical approach, taking into account the characteristics of each element that support the antenna, has been taken to assess the potential stability of all DORIS occupations. IGN is also in charge of its operational maintenance, an intensive activity on account of the significant failure rate of the successive generations of equipment. Nevertheless, thanks to its unique density and homogeneity, DORIS has maintained a very good coverage rate of the satellite orbits. Through 38 well-distributed current co-locations with the Global Positioning System, Satellite Laser Ranging and Very Long Baseline Interferometry techniques in its current 56-station network, DORIS contributes significantly to the realisation of the International Terrestrial Reference System. DORIS stations in areas where no other space geodesy technique is available provide a significant contribution to the study of plate tectonics. Many stations co-located with tide gauges contribute to the monitoring of sea level changes. Although it has several advantages over similar techniques, there is still room for improvement in the DORIS network.

Maximization of structural natural frequency with optimal support layout

The optimal layout of supports is one of the key factors that dominates static and dynamic performances of the structure. In this work, supports are considered as elastic springs. The purpose is to carry out layout optimization of supports by means of topology optimization method. The technique of pseudo-density variables that transforms a discrete-variable problem into a continuous one is used in order that the problem is easily formulated and solved numerically. In this formulation, a power law of the so-called solid isotropic material with penalty model is employed to approximate the relation between the element stiffness matrix and density variable. Such a relation makes it easy to establish the computing scheme and sensitivity analysis of natural frequency. Support layout design that corresponds to optimization of boundary conditions is studied to maximize the natural frequency of structures. Numerical results show that reasonable distributions of supports can be generated effectively.