Force Transmission Path Research Articles

Optimization for Side Structure of Vehicle Based on FEA

This paper takes the electric vehicle with HV battery traction which has achieved the "five-star" result of CNCAP as the research object, and uses HyperMesh and LS-DYNA to establish a lateral impact finite element model for simulation to verify the performance of this vehicle in C-IASI. In order to improve the performance of the side structure, the structure is optimized by upgrading the materials of key components, optimizing the key force transmission path and filling the cavity in the key deformation area with polymer structural stiffeners. According to the optimization scheme, the finite element model is established and calculated. The results show that the optimization scheme can effectively solve the problem of excessive intrusion and intrusion speed of the inner plate of the B-pillar in side impact, and improve the deformation mode of the B-pillar at the same time, improve the side impact safety performance of the vehicle, meet the requirements of "GOOD", and provide a reference for the solution of similar problems of subsequent related vehicles.

Progressive collapse resistance of composite frame with concrete-filled steel tubular column under a penultimate column removal scenario

In this study, static tests of six two-story three-span composite frames with concrete-filled steel tubular (CFST) column under a penultimate column removal scenario were carried out. The experimental phenomena, vertical resistance, strain and axial force of steel beams were presented. The internal force transmission path of composite frame under a penultimate column removal scenario was investigated. The effects of reinforced concrete (RC) slab and weld-bolted connection on the progressive collapse resistance of composite frame were analyzed and discussed. Consequently, the dynamic response prediction and dynamic amplification factor (DAF) were analytically studied by energy balanced method (EBM). Further, the numerical models of composite frames were calibrated by the test results in ABAQUS/Explicit. The results showed that serious torsion of steel beam at directly affected region (DAR) reduced the resistance for the CFST frames with bare steel beam. However, for the CFST frames with composite beam (i.e., with steel beam and RC slab), the RC slab improved the initial stiffness and peak resistance of composite frame and thus mitigated and even prevented the torsion of beam. The composite frames presented an asymmetric failure mode and internal force transmission path under a penultimate column removal scenario, which was different from that under a middle column removal scenario. The composite frames with weld-bolted connection presented a lower resistance than the composite frames with welded connection due to the premature fracture of welded flanges but possessed multi-protection measures to resist progressive collapse due to the intermittent failure modes.

Experimental study on seismic performance of new-type fabricated shear wall with mortar connection

This paper proposes a new type of fabricated shear wall system, that is, the two ends of the horizontally distributed ribs and the top of the vertical distributed ribs are reliably connected with the cast-in-situ belt, and the bottom of the vertical distributed ribs is not penetrated and only connected by mortar. To study the seismic performance of the new wall, 7 specimens of the shear wall were designed and manufactured, including 2 cast-in-place shear walls and 5 new fabricated shear walls. Through low-cycle reciprocating loading tests, different analyses were made. Shear span ratio and different edge restraint structure of the new fabricated shear wall failure mode, bearing capacity and other seismic performance, and through OpenSees finite element analysis of the wall to verify the correctness of the modelling method. The test results show that the failure characteristics of the new wall are mainly the cracking and penetration of the mortar layer, the crushing of the corner concrete and the local buckling of the steel bars at the bottom of the edge members; compared with the cast-in-place wall, the new wall has the lower bearing capacity, but the deformation and energy consumption are not much different. The reinforced edge members can effectively compensate for the weakening of the integrity of the wall panel caused by the discontinuity of vertical steel bars. Among the 7 specimens, the overall performance of the wall with increased longitudinal reinforcement ratio is the best. The error between the wall finite element results and the test results is less than 5%, which shows that the modelling method in this paper has sufficient accuracy for the evaluation of the seismic performance of the new wall. In general, the new prefabricated shear wall system is feasible in high-rise buildings. • A new type of fabricated shear wall system is proposed. • The bottom of the vertical distribution bar of the wall panel is disconnected, and only connected by setting mortar. • This system is simple to construct, fast, low cost, clear force transmission path, clear seismic performance, and more importantly, easy to detect.

Mechanical Properties and Energy Conservation Analysis for The New Connection of The Fabricated Shear Wall

In order to investigate a reliable reinforcement connection form for the assembly nodes of the fabricated reinforced concrete shear walls with joint seams, and explore a reinforced bars lap splice method with easy control of construction quality, a new type of reinforced bars lap splice method with the additional X-shaped reinforcement at the assembly nodes is proposed. By changing the width of the assembly nodes, three fabricated shear wall models were designed. By using Abaqus finite element analysis software, the full-range numerical simulations of its mechanical properties under static load were carried out to study the behaviors of the new reinforced bars lap splice method, which were compared with the behaviors of the cast-in-place monolithic shear wall with the same design parameters and analyzed. The results show that the additional X-shaped reinforcement changed the force transmission path of the reinforced bars lap splice at the assembly nodes and reduced the cross-sectional stress of lap splice area, and improved the reliability of the weak part of the fabricated shear walls. The method also reduced the difficulty of assembling fabricated shear wall structure. Comparing the fabricated shear walls in the same assembly position, the analyses show that the reinforced bars lap splice with the additional X-shaped reinforcement is not sensitive to joint seam width, which can realize the shear walls can assemble with small seam width, and effectively improves prefabrication rate.

Research on ultimate bearing capacity state and structure optimization of main cable saddle

In order to make the main cable saddle structure lighter and reduce the cost, it is necessary to conduct in-depth research on the force transmission path, failure mode and ultimate bearing capacity of the main cable saddle. A parametric geometric model was established based on Autodesk Inventor software and imported into the large-scale general-purpose finite element software ABAQUS for numerical simulation research under ideal elastoplastic state, and the mechanical properties and ultimate bearing capacity of the main saddle were systematically studied. A structural optimization method with safety factor as the goal was proposed, and the original design was optimized for structural size. Then, the ultimate bearing capacity state of the cable saddle considering the influence of the steel's post-buckling strength is analyzed, and the structural bearing capacity evaluation index is proposed. The analysis results show that the ultimate bearing capacity of the preliminary design cable saddle is 3.00 times the design load, and it has sufficient safety reserves; the ultimate failure state of the cable saddle is the formation of a plastic hinge at the junction of the transverse rib, saddle channel cast steel and the web; By quantitatively analyzing the development of the plastic zone of each component of the cable saddle, the force transmission path and failure process of the structure can be analyzed more clearly, which provides a basis for the structural optimization of the cable saddle; and obtain the steel consumption under different safety factor target values (2.5, 2.0, 1.85, 1.5, 1.25), for example, when the safety factor target is 1.85, 38.8% of steel can be saved; when considering deformation index control, it is recommended that the target safety factor of the ideal elastoplastic analysis control is not less than 1.82.

Topological Design of a Mortar Base Plate under Impact Loads

In this work, the topology optimization of a mortar base plate is analysed under impact loading conditions. Usually, in this case, only ordinary topology optimization under volume constraints is considered. However, to reduce the quality of the mortar base plate and facilitate engineering applications, the topological optimization problem of the continuum of the base plate under the engineering and quality constraint is considered. A finite element model has been established and verified by testing for the mortar base plate. The variable density method was used to obtain the topological optimization results of the base plate based on the force transmission path, and then the structure was reconstructed. The mass of the optimization model of the base plate is 12.78% lower than that of the original model. In comparison with the original base plate before optimization, the results show that the maximum deformation and stress of the base plate decreased by 16.85% and 35.52%, respectively. Also, the firing stability of the mortar meets requirements, which not only meet the design requirement but also provide a reference for the performance improvement and structural optimization design of the base plate.

Lightweight design of a certain mortar base plate based on sensitivity analysis

In order to resolve the inconvenience in usage and transport pertaining to a certain mortar base plate due to its large mass, dimension optimization, topology optimization and composite material optimization were first applied in an integrated manner to the lightweight design of the base plate on the premise of ensuring the strength and good firing stability of the base plate; and the lightweight design of the base plate was realized. The finite element model of the mortar base plate was established; and the correctness of the model was verified by modal testing. Sensitivity analysis was conducted on the five main structural parameters influencing the stiffness and strength of the base plate by a sensitivity analysis method based on DOE and regression analysis, so as to provide an effective basis for the lightweight design of the base plate. Dimension optimization was performed on the parameter greatly influencing the maximum stress on the base plate and topology optimization on the parameter region that has minor influence to obtain the main force transmission path in this region. Composite materials were used to replace the materials in the non-main force transmission region to design a composite base plate; and the thickness of the laminate was optimized. The results of numerical calculation showed that the base plate lost 30.33% of weight after the lightweight design and that the strength and firing stability fully met the requirements. This study provided a new clear design idea for the lightweight design of mortar base plate and provided reference for the lightweight design of other models of mortar base plate.

Analysis of the Force Characteristics of the Chinese Wooden Dou-Gong Brackets in the Ming Dynasty

The Dou-Gong bracket is the most unique part of Chinese wooden architecture. It has an exquisite structure and complex stress. It bears the important force-bearing components between the beam and the column. Different Dou-Gong in different historical periods has different structures and characteristics. This article takes the Jinci Mirror Terrace in the Ming Dynasty as an example and uses the Abaqus to simulate the vertical force to analyze its force characteristics and force transmission path. At the same time, comparing the actual damage of the ancient buildings, it is found that they are consistent with the simulation phenomenon, which proves that the stress simulation of the Dou-Gong has certain guiding significance, and thus summarizes the weak points of the Gou-Gong in the Ming Dynasty, to provide a basis for the daily protection and reinforcement of the Gou-Gong brackets.

Development of a soft cable-driven hand exoskeleton for assisted rehabilitation training

PurposeHand motor dysfunction has seriously reduced people’s quality of life. The purpose of this paper is to solve this problem; different soft exoskeleton robots have been developed because of their good application prospects in assistance. In this paper, a new soft hand exoskeleton is designed to help people conduct rehabilitation training.Design/methodology/approachThe proposed soft exoskeleton is an under-actuated cable-driven mechanism, which optimizes the force transmission path and many local structures. Specifically, the path of force transmission is optimized and cables are wound around cam-shaped spools to prevent cables lose during fingers movement. Besides, a pre-tightening system is presented to adjust the preload force of the cable-tube. Moreover, a passive brake mechanism is proposed to prevent the cables from falling off the spools when the remote side is relaxed.FindingsFinally, three control strategies are proposed to assist in rehabilitation training. Results show that the average correlation coefficient of trajectory tracking is 90.99% and this exoskeleton could provide steady clamping force up to 35 N, which could meet the demands of activities in daily living. Surface electromyography (sEMG)-based intention recognition method is presented to complete assistance and experiments are conducted to prove the effectiveness of the assisted grasping method by monitoring muscle activation, finger angle and interactive force.Research limitations/implicationsHowever, the system should be further optimized in terms of hardware and control to reduce delays. In addition, more clinical trials should be conducted to evaluate the effect of the proposed rehabilitation strategies.Social implicationsMay improve the ability of hemiplegic patients to live independently.Originality/valueA novel under-actuated soft hand exoskeleton structure is proposed, and an sEMG-based auxiliary grasping control strategy is presented to help hemiplegic patients conduct rehabilitation training.

Structure design of LFT passenger car seat structure based on topology optimisation

The newly revised GB 13057-2014 ‘The strength of the seats and their anchorages of passenger vehicles’ replaces the static test with a dynamic test, which puts forward higher requirements on seat safety. Considering safety and lightweight design, the LFT (Long glass Fiber reinforced Thermoplastic) is used to replace the original steel seat back frame. Combined with energy absorption model and topology optimisation, the force transmission path and detail structure design under both the forward loading and rearward loading conditions are carried out. In order to analyse the occupant protection performance, numerical models of composite seat and HybridIII dummy are established, and the safety and lightweight effect of LFT seat back frame are optimised and verified.

A Cumulative Expansion Force‐Finding Method for Suspension‐Cable Truss Composite Structure

Suspension‐cable truss composite structure is a new type of cable‐strut structure which combines the conventional cable structure with the rigid truss. By laying rigid roofing slabs, this composite structure offsets most effect of the wind suction, reduces the axial force of the stable cables, and reduces the large vertical displacement effectively when compared with conventional cable trusses. For this new structure, the deformation relevance between adjacent substructures results in a nonindependent and stable union. To effectively and precisely find the cable forces of a suspension‐cable truss composite structure for the construction completion state, a proper optimization order and a suitable selection of the substructures are necessary. In this paper, the structural mechanical characteristics of the suspension‐cable truss composite structure are introduced at first, to reveal the force transmission path between adjacent substructures. Secondly, the cumulative expansion force‐finding method (CEFM) is proposed to obtain the optimal mode of the cable force distribution with a suitable operational efficiency. A numerical example is introduced and analyzed to verify the accuracy and feasibility of this method afterwards. The results show that CEFM could find out the optimal cable force distribution of the suspension‐cable truss composite structure, with a geometry shape of whole structure and a rational stress level of all the components.

Multi-objective optimization of crashworthiness of vehicle front longitudinal beam

Front longitudinal beam (FLB) is an important structure for the analysis of force transmission and energy absorption path in different crashing scenarios. In the present paper, the finite element (FE) model of a full-scale vehicle yun-100 Zotye is employed to explore the energy absorption of FLB, and aiming at its poor energy absorption problem, circular beam was used as the original topology optimization space of FLB. The advantages of both static and dynamic topology optimization methods are fully considered, and a variable density method is combined with a hybrid cellular automaton (HCA) method. The substructure dissipated energy and force for frontal crash in a full-scale vehicle are obtained at a speed of 13.8 m/s. The maximum stiffness in axial is obtained through the static topology optimization method and the maximum energy-absorbing structure of FLB which is satisfied with axial strength obtained through the dynamic topology optimization method. According to the results of topology optimization, a multi-cell thin-walled structure is interpreted as the novel FLB. A parametric study on geometric parameters is also performed to explore their effects on crashing characteristics of novel FLB, and it is found that they significantly influenced the crashworthiness of multi-cell thin-walled structure (especially the absorption of energy). Furthermore, in order to maximize the characteristics of novel FLB, a multi-objective optimization process is carried out using non-dominated sorting genetic algorithm (NSGA-II). The optimized FLB after multi-objective optimization is applied to Zotye of 100% vehicle frontal crash. The results showed that the peak value of acceleration decreased by 10.3% and the mass of the optimized FLB reduced to 0.59 kg. It indicated that the optimized FLB manifested excellent crashworthiness and better protective characteristics.

Topology optimization design for offshore platform jacket structure

Offshore jacket platform is widely used as production or oil recovering platform in the shallow sea, and is also applied to the offshore wind turbine supporting structure in the recent years. The jacket structures are normally designed to be conservative and bulky according to various design codes. In this work, a structural optimization design method for jacket platform structure has been developed based on topology optimization theory. The topology optimization method is applicable at an early design stage, which can determine the initial structure and force transmission path. The whole design space is chosen as design variables, and the goal is to maximize the structural stiffness. A set of constraints based on multi-criteria design assessment is applied according to standard requirements, which includes stress, deformation, vibration and design variable constraints. The optimization results are compared with the original platform for static performance, dynamic performance and Ultimate Carrying Capacity (UCC). Results show that the optimized structure show a 13.7% reduction in the global mass, 46.31% reduction in the maximum equivalent stress, and large ultimate carrying capacity ability under the same environmental loads. It is demonstrated that the proposed topology optimization method is capable of effectively determining the optimal design of jacket platform structures.

Numerical Study of Damage Evolution Law of Coal Mine Roadway by Particle Flow Code (PFC) Model

Deformation and destruction of roadway surrounding rock is one of the main causes of coal mine accidents. In this paper, the horseshoe-shaped roadway model was established by particle flow code firstly and then analyzed the roadway damage process through the contact force chain, deformation displacement and distribution of micro-cracks. The research result show that the parallel bond model can well simulate the damage process of the coal mine roadway. The surrounding rock can be divided into four zones from the roadway side to the deep rock mass. The micro-contact force chain is the force transmission path and the principal stress is the macroscopic reflection of the micro-contact force chain.

Structural Optimization Method for the Transition Section in Composite Bucket Foundations of Offshore Wind Turbines

A two-step structural optimization method was proposed to select the transition section of a composite bucket foundation (CBF). In the first step, based on the variable density method, a solid isotropic microstructures with penalization (SIMP) interpolation model was established under specific load conditions and boundary conditions. The solution of force transmission path and the topology of the transition section in six forms (e.g., linear, arc-shaped, linear thin-walled, and arc-shaped thin-walled) were optimized. Afterwards, finite element software ABAQUS was used to verify this model. Results show that the utilization rate of the arc-shaped thin-walled structure was the largest, and its basic transmission force was more straightforward together with smaller cross-section size at the same height and smaller influence on spoiler flow. In the second step, the detailed optimization of CBF was carried out using mathematical programming. Under the premise of minimum total construction cost, the body shape parameters of each part were set as design variables satisfying the corresponding strength, stiffness, and stability conditions; meanwhile, the minimum total structure weight was set as the objective function. MATLAB was used to solve the sequence quadratic programming (SQP) algorithm and hybrid genetic algorithm, and the optimal body parameters were obtained.

Three-dimensional dynamic response analysis of a single-ring structure in a prefabricated subway station

Traditional subway construction technology still mainly involves on-site poured concrete construction, which causes many social and environmental problems and at the same time is not compatible with the modern concept of resilient city construction and sustainable development. A new prefabricated subway station construction technology can effectively solve many of the problems caused by traditional cast-in-situ technology and provide for the sustainable development of subway construction programmes. As an important part of an urban lifeline system, the seismic performance of subway stations has always attracted much attention. This paper focuses on the dynamic response of the single-ring structure of a prefabricated subway station under horizontal earthquake shaking. Using the commercial finite element software ABAQUS, numerical analysis models of two large-scale underground structures have been developed: the single-ring structure of a prefabricated subway station and the traditional cast-in-situ subway station. Under the same earthquake action, there are obvious differences between the prefabricated structure and the traditional cast-in-place structure. Compared to the seismic response of traditional cast-in-situ structures, the ground acceleration response of the prefabricated structure is slightly reduced, the overall deformation is slightly increased, the maximum internal force and stresses are significantly reduced, the internal force transmission path is changed, and the area of influence in the surrounding soil is significantly reduced. Comprehensive comparative analysis shows that the single-ring structure of the prefabricated subway station has good deformation resistance and excellent mechanical properties under horizontal earthquake shaking and the overall seismic performance meets the design requirements. Finally, the seismic response characteristics and energy dissipation advantages of the prefabricated single-ring structure are discussed. The research conclusions will provide useful references for resilient city construction and sustainable urban development.

Experimental investigations of force transmission characteristics in granular flow lubrication

PurposeGranular lubrication is a new lubrication method and can be used in extreme working conditions; however, the obstacle of force transmission characteristics needs to be urgently solved to fully understand the mechanical and bearing mechanisms of granular lubrication.Design/methodology/approachA flat sliding friction cell is developed to study the force transmission behaviors of granules under shearing. Granular material, sliding velocity, granule size and granule humidity are considered in these experiments. The measured normal and shear force, which is transmitted from the bottom friction pair to the top friction pair via the granular lubrication medium, reveals the influence of these controlling parameters on the force transmission characteristics of granules.FindingsExperimental results show that a low sliding velocity, a large granule size and a low granular humidity increase the measured normal force and shear force. Besides, a comparison experiment with other typical lubrication styles is also carried out. The force transmission under granular lubrication is mainly dependent on the force transmission path, which is closely related to the deconstruction and reconstruction of the force chains in the granule assembly.Originality/valueThese findings reveal the force transmission mechanism of granular lubrication and can also offer the helpful reference for the design of the new granular lubrication bearing.

Topology Optimization Design of Launcher Bracket Based on Multi-body Dynamics

According to the topology optimization theory and engineering application, a launcher bracket topology optimization finite element model was built, which was based on the multi-body dynamics simulation. The optimal material distribution and the force transmission path of the bracket under the constraint conditions were obtained. The stiffness evaluation standard for bracket structure is established by introducing the specific stiffness structural effectiveness. After comparative and analysis, the simulation results show that the topology optimization design of launcher bracket based on multi-body dynamics can achieve the lightweight design of launcher bracket, strengthen structure stiffness, increase the bracket modal frequency, which are helpful to reduce the initial disturbance of missile launching. The method provides reference for the design of similar products.

The Performance of Resistance Progressive Collapse Analysis for High-Rise Frame-Shear Structure Based on OpenSees

A finite element model (FEM) of frame-shear structure was constructed using OpenSees program based on the nonlinear flexibility theory and multi-vertical-line theory that considered bending-shear coupling, and its progressive collapse resistance under abnormal conditions was analyzed. Flexibility-based method for modeling shear wall finite element and multi-vertical-line element (SFI-MVLEM) was proposed. Method of deleting failure component elements was presented, as well as the model solving algorithm. The FEM was validated by the completed structure test. On these bases, 3 groups of typical frame-shear structure systems were designed to perform nonlinear dynamic collapse analysis under different initial failure conditions, in order to study the impact of the number of floors and earthquake resistant design on the progressive collapse resistance of frame-shear structures. Analysis results showed that, at initial failure of frame column, the residual shear wall element can well complete the internal force redistribution of structure to provide alternative force transmission path, thereby forming antiprogressive collapse force. In the case of initial failure of shear wall, C-shaped shear wall can form alternative path to diminish the vertical deformation of frame-shear structures. Final comparison shows that the structural seismic design can effectively improve their anticollapse performance.

Discussion of the Masonry Structure Building Underpinning Method

In masonry structure transformation, due to the removal of walls, force transmission path and force structure mechanism of load-bearing walls will be changed. So it become greatly important to adopt a safe, applicable, economic and reasonable underpinning method. This paper introduces several underpinning methods of masonry structure modification, which summarizes the advantages and disadvantages of them. Their characteristics and using condition are discusses in the paper. Some conclusions which are drawn may be referenced for the future engineering practice.