Plastic Energy Dissipation Research Articles

Low cycle fatigue response of differently aged AA6063 alloy: Statistical analysis and microstructural evolution

Understanding the dynamic structural changes during cyclic deformation of Al-alloys is a discipline of great interest to material technologists. The primary objective of this report is to assess the low cycle fatigue (LCF) behaviour of AA6063 alloy in under-aged (UA), peak-aged (PA) and over-aged (OA) states and to understand the energetic aspects of cyclic plastic behaviour in the background of the nature and density of the dislocations. Two parameters Weibull distribution analyses, for the first time, establish that despite inferior monotonic strength, LCF life of UA alloy is twice compared to PA alloy at higher (≥0.5%) strain amplitudes. This corroborates well with the fact that the cumulative dissipated plastic strain energy density (CPSED) values exhibit reverse variation with applied strain amplitude in the case of UA alloy as compared to PA and OA alloys. TEM analyses confirm that strain-induced vacancy-driven dynamic precipitation causes dramatic cyclic hardening in UA alloy resulting in improved fatigue life. One can also evidence this from the fivefold increase in the plastic strain energy dissipation and 2-times increased of post-fatigue hardness. In contrast, fracture surface analyses and XRD-based dislocation density measurements coupled with TEM examinations reveal that the shearing or by-passing of precipitates by the dislocations in the PA or OA alloys, respectively, lead to strain localization and cyclic softening, and consequently, reduce the plastic strain energy dissipation and lower fatigue life. The study provides important guidelines for the development of high strength Al-alloys with improved fatigue performance.

Removal of glycosaminoglycans affects the in situ mechanical behavior of extrafibrillar matrix in bone

Previous studies have shown that glycosaminoglycans (GAGs) in bone matrix, coupling with water in bone matrix, may play a significant role in toughening bone tissues. Since GAGs are most likely present only in the extrafibrillar matrix (EFM) of bone, we hypothesized that GAGs in EFM would have a major impact on bone tissue toughness. To confirm this conjecture, we removed GAGs ex vivo from human cadaveric bone samples using a protein deglycosylation mix kit and then examined the in situ mechanical behavior of mineralized collagen fibrils (MCFs) and the surrounding EFM of the samples, using a high-resolution atomic force microscopy (AFM). By testing the bone samples before and after removal of GAGs, we found that under the wet condition removal of GAGs resulted in an increase in the elastic modulus of both EFM and MCFs, whereas a significant decrease in plastic energy dissipation was observed mainly in EFM. In contrast, under the dry condition the removal of GAGs had little effects on the mechanical properties of either MCFs or EFM. These results suggest that both MCFs and EFM contribute to the plastic energy dissipation of bone, whereas in the presence of matrix water removal of GAGs significantly reduces the capacity of EFM in plastic energy dissipation, but not MCFs. In addition, GAGs may affect the elastic modulus of both EFM and MCFs. These findings give rise to new understanding to the underlying mechanism of GAGs in toughening of bone tissues.

A resilient column with angular friction damper for seismic performance upgrading of underground structures

Underground structures can be vulnerable due to seismic-induced deformation. A resilient underground structure is preferable for seismic response mitigation and quick recovery. In this study, a resilient central column with angular friction damper (RC-AFD) was constructed for the seismic performance upgrading of underground structures, and a practical design procedure was developed for the RC-AFD to enable the two-state control for underground structures subject to seismic excitations with multi-intensity. The RC-AFD consists of a self-centering column characterized by relaxed constraints at the top and bottom column that is restricted by unbounded prestressed tendons, whereas a pair of angular friction dampers are placed at the top of the central column. The mechanical model and its physical realization are detailed, whereas the two-state control mechanism is proposed by following the enhanced demand of seismic performance upgrading. The effectiveness and robustness of the proposed RC-AFD for structural seismic response mitigation of typical underground structures were investigated in terms of structural displacement, shear force, bending moments, and energy-based responses. The obtained results show that the two flexible connection joints concentrated at the top and bottom of the RC-AFD produce a significant isolation effect, through which the multiple responses of the central column can be reduced significantly. Benefiting from the two-state design and the employed angular friction damper with a large radius plate, the RC-AFD exhibits an enhanced energy dissipation capacity, which robustly dissipates the intense plastic energy for multi-intensity excitations. As a consequence, the plastic energy dissipation burden of the primary structures can be significantly relieved and residual deformation can be avoided due to the excellent self-centering ability.

Experimental and numerical research on the multi-stage seismic failure modes of steel frame with end-plate connection

To study the multi-stage seismic failure mode of semi-rigid plane steel frame with end-plate connection, one 1/2-scale specimen of the quasi-static cyclic test was conducted. According to the failure criteria, the mechanical characteristics and the failure process of the specimen at three performance stages (the elastic stage, the elastoplastic stage, and the ultimate stage) were studied. The bearing capacity, stiffness degradation, and the plastic energy dissipation of the test specimen were also analyzed. Moreover, a nonlinear finite element model of the specimen was implemented in the ABAQUS platform to compare and verify the test results, and a parametric analysis was conducted to investigate the influence of the thickness ratio (δ = te/tf) of the end-plate (te) to the column flange (tf) on frame performance. The specimen has reliable energy dissipation capacity and ductility, and the lateral displacement of the first story accounted for about 40% of the second story displacement, while this ratio increased to 50% in the ultimate stage. The increase of δ can significantly improve the lateral stiffness and bearing capacity of the specimens, but the ductility decreases gradually. The failure order of the specimen was the yield of the end-plate, the yield of the beam end, the buckling of the column base, and the failure of the whole frame, which indicated that the specimen satisfied the design criteria of “strong column weak beam”.

Method for studying the kinetics of plastic deformation and energy dissipation during fatigue of structural materials

The evolution of mechanical properties of Russian steel St3 subjected to cyclic elasto-plastic deformation is analyzed under a broad spectrum of loading conditions. This particular material is chosen due to its wide use in industrial facilities operating in Arctic and Russian North. Basic state parameters are determined, including the true strains, secant and tangent moduli, heat generation due to plastic dissipation, thus characterizing the evolution of the thermo-mechanical state. The temporal evolution of kinetic parameters during each loading block provides insights into the hardening and damage accumulation. These data form an experimental basis for development, calibration, and validation of new material models. The main effects are identified and discussed, and the modelling approaches are assessed.

Computational Modeling and Energy Absorption Behavior of Thin-Walled Tubes with the Kresling Origami Pattern

Origami structures have been widely used in various engineering fields due to their desirable properties such as geometric transformability and high specific energy absorption. Based on the Kresling origami pattern, this study proposes a type of thin-walled origami tube the structural configuration of which is found by a mixed-integer linear programming model. Using finite element analysis, a reasonable configuration of a thin-walled tube with the Kresling pattern is firstly analyzed. Then, the influences of different material properties, the rotation angle of the upper and lower sections of the tube unit, and cross-sectional shapes on the energy absorption behavior of the thin-walled tubes under axial compression are evaluated. The results show that the symmetric thin-walled tube with the Kresling pattern is a reasonable choice for energy absorption purposes. Compared with thin-walled prismatic tubes, the thin-walled tube with the Kresling pattern substantially reduces the initial peak force and the average crushing force, without significantly reducing its energy absorption capacity; moreover, it enters the plastic energy dissipation stage ahead of time, giving it a superior energy absorption performance. Besides, the material properties, rotation angle, and cross-sectional shape have considerable influences on its energy absorption performance. The results provide a basis for the application of the Kresling origami pattern in the design of thin-walled energy-absorbingstructures.

Seismic behaviour of frame structures with assembly of prefabricated concrete beam

This study investigates a novel prefabricated concrete frame beam with an innovative assembly pattern that is cost-effective, reliable, practical, and has a good fault-tolerance. Quasi-static cyclic experiments were carried out on a cast-in-place (CIP) beam and three precast concrete (PC) beams with different lengths or widths of protruding beam stumps. The cracking propagation mode, load-bearing capacity, beam ductility, beam stiffness, and plastic energy dissipation ability were comparatively analysed. It is concluded that the hysteretic behaviour of the PC beams with the innovative assembly pattern suggested in this study was similar to that of the CIP. Moreover, PC beams with a wider protruding beam stump displayed better seismic performance. In particular, development curves of crack width with cyclic load were obtained, which showed that the cracks widened gradually as the number of load cycles increased, and the main crack width increased significantly around the peak load. A finite element model (ABAQUS) was established to further reveal the working mechanisms and conduct a parametric investigation of the PC beams. Parametric simulations indicated that a reasonable and relatively larger thickness of the U-shaped beam shell and higher post-pouring concrete strength are recommended for practical applications of the proposed novel prefabricated concrete frame beams.

Effect of metal type on the energy absorption of fiber metal laminates under low-velocity impact

The energy dissipation mechanisms during impact including damage evolution and plastic deformation of FMLs with different metal layers named aluminum and magnesium was experimentally and numerically studied. A 3D failure criterion for composite damage evolution was developed. The impact energy of the FMLs was mostly dissipated by metal layers, where the plastic dissipation energy of each aluminum layer in aluminum-based FMLs was distinctly higher than that of magnesium layer in magnesium-based FMLs. Replacing aluminum in FMLs with magnesium leads to faster perforation and passive energy dissipation, but will also reduce delamination damage at metal-composite interface due to smaller plastic deformation.

An approach for fatigue life prediction based on external heating

An approach is presented to predict fatigue life and energy dissipation based on the measurement of the electrical power consumption of an external heat source. In this method, the steady-state temperature profile of a specimen experiencing cyclic fatigue test is reproduced simply by externally heating the specimen with an electric coil with a DC source. The results show a direct relationship between the electric power consumption of heating coils and the fatigue plastic energy dissipation. This relationship is used as a tool to predict fatigue life.

Hysteretic behavior of CFST column-steel beam bolted joints with external reinforcing diaphragm

In this study, three concrete-filled steel tubular (CFST) column-steel beam bolted joints with external reinforcing diaphragm were tested under cyclic loading using 1/2 scaled specimens, and the influence law of steel beam size and tie plate of high-strength bolts on the failure modes were discussed. The ABAQUS program was used to establish the three-dimensional solid finite element models of the joints, and the joint models were then verified by the test data. Taking the welded rigid joint with external reinforcing diaphragm as the benchmark, a connection detailing of bolted rigid joint and a method for classifying the joint were proposed. The stiffness, bearing capacity and plastic energy dissipation of the bolted joints with different structural detailing and reinforcing measures were compared and analyzed. The obtained results show that the bolted joints with external reinforcing diaphragm can be classified as semi-rigid joint. The stiffness and bearing capacity of the bolted joint can almost be equivalent with the welded rigid joint counterparts, when the external reinforcing diaphragm with stiffeners was connected to the steel beam using four rows of bolts and simultaneously setting web stiffeners at the beam ends. With the above configuration, the total plastic energy dissipation of the bolted joint is over 80% of that of the welded rigid joint counterpart, and the steel beam is found to be the main component contributing the plastic energy dissipation.

The relation between fatigue crack growth rate and plastic energy dissipation in 7075-T6

Plastic dissipation accompanies fatigue crack growth in ductile materials. Previous studies presented a relation between plastic dissipation (dW/dN) and the fatigue crack growth rate (da/dN), where some researchers assumed a linear relation between both to enable crack growth predictions. To study the validity of this assumption, this paper reports an experimental study on fatigue crack growth in 7075-T6, an alloy widely used in aerospace. The experimental results suggest, however, a nonlinear relation between dW/dN and da/dN in 7075-T6. The value of dW/da, indicating the plastic dissipation per unit fatigue crack growth, is not constant. Hence for 7075-T6 it is concluded that dW/dN cannot be used directly to predict da/dN.

A deep neural network inverse solution to recover pre-crash impact data of car collisions

In this work, we have successfully developed a data-driven artificial intelligence (AI) inverse problem solution for traffic collision reconstruction. In specific, we have developed and implemented a machine learning computational algorithm and built a deep neural network to determine and identify the initial impact conditions of car crash based on its final material damage state and permanently deformed structure configuration (wreckage).In this work, we have demonstrated that the developed machine learning algorithm as an inverse problem solver can accurately identify initial collision conditions in an inverse manner, which are practically unique if we use permanent plastic deformation as the forensic data signatures. In other words, we think that the massive plastic energy dissipation process and the related big data will make final structure damage state insensitive to the initial car collision conditions. Thus, it provides an inverse solution for car crash forensic analysis by reconstructing the initial failure load parameters and conditions based on the permanent plastic deformation distribution of cars. This approach has general significance in solving the inverse problem for engineering failure analysis and vehicle crashworthiness analysis, which provides a key contribution for the unmanned autonomous vehicle and the related technology.

Experimental and numerical studies of an axial tension-compression corrugated steel plate damper

Metallic dampers are widely used due to their satisfactory plastic energy dissipation, low price and convenient installation. In this study, an axial tension and compression corrugated steel plate damper (ATCCSPD) was proposed. According to the mechanical properties of the ATCCSPD, low-frequency cyclic loading tests and numerical verification of seven ATCCSPD specimens were designed and performed. Additionally, the test phenomena and failure modes of the ATCCSPD specimens were analysed, and seismic performance indices such as the hysteretic curve, skeleton curve, ductility and energy dissipation were obtained. Then, the impacts of the thickness of the corrugated web, the aspect ratio and the thickness of the flange on the seismic behaviour of the ATCCSPD specimens were investigated. The results demonstrated that the seven ATCCSPD specimens exhibited satisfactory ductility and energy dissipation capacity, and the hysteretic curves were stable and full. Overall, the ATCCSPD specimens exhibited axial tension and compression deformation, while the internal corrugated web exhibited pure shear deformation during the loading process. The web thickness and aspect ratio were the main factors affecting the bearing capacity and energy dissipation of the ATCCSPD specimens. The finite element software ABAQUS was used to simulate the ATCCSPD specimens, and shear damage was added to the nonlinear kinematic hardening constitutive model of steel, which could effectively simulate the failure process of the corresponding part after cracks formed in the ATCCSPD specimens. Finally, combined with the test results and the numerical results, the shear bearing capacity formula of the corrugated webs was fitted; then, the formula for calculating the tensile (compressive) bearing capacity of the ATCCSPD specimens was obtained by the superposition principle. By comparing the calculation results with the test results, it was found that the proposed formula was conservative and, hence, suitable for engineering applications.

Efficient analysis of cyclic laterally loaded piles

The analysis and design of piles subjected to lateral cyclic loads that induce significant plastic responses requires numerical models for the lateral soil resistance capable of representing the fundamental soil responses observed in such conditions. A bounding surface plasticity model with traditional p-y concepts has been implemented in a finite element model and successfully benchmarked against physical tests revealing significant cyclic responses in both one- and two-way loading conditions. The model includes two kinematic hardening surfaces and a fixed limit surface beyond which the kinematic surfaces cannot pass. The benchmarking effort resulted in standardized values for several model parameters for p-y applications. The remaining model parameters are easily calibrated against the expected p-y response under monotonic loading conditions for fine grained soils. The analysis method is extremely efficient, requiring the same level of effort as that typical of traditional p-y techniques. The results presented demonstrate that the model accurately reproduces observed pile cyclic hysteresis, plastic energy dissipation, and stiffness degradation, all of which are neglected in traditional elasticity-based p-y models. It has distinct advantages for static and dynamic analyses involving complex loading histories involving significant plastic soil response and is suitable for site specific analyses. This study is confined to planar conditions, but similar models have been implemented for arbitrary loading directions.

Investigation of the Cross-Cutting Polycrystalline Diamond Compact Bit Drilling Efficiency

The parallel track scraping principle of conventional PDC bits largely limits the cutting efficiency and working life in deep formations. Cross-cutting polycrystalline diamond compact (PDC) bit may be an efficient drilling tool that increases the rock-breaking efficiency through both cross-cutting and alternate-cutting modes of the PDC cutter. The motion track equation of the cross-cutting PDC bit was derived by using the compound coordinate system, and the motion track was analyzed. Meanwhile, through the unit experiment and discrete element simulation, the cutting force, volume-specific load, and crack propagation were analyzed under different cutting modes. Through establishing a nonlinear dynamic model of the bit-rock system, the speed-up mechanism of the novel bit was analyzed based on rock damage, rock stress state, and motion characteristic of the bit during the rock-breaking process. Compared with unidirectional cutting, cross-cutting produces less cutting force, more brittle fracture, and a greater decrease of formation strength. The novel PDC bit can put more rock elements into a tensile stress condition than a conventional PDC bit, and the plastic energy dissipation ratio of the cross-cutting PDC bit is lower while the damage energy consumption ratio is higher than they are for conventional bits, which is beneficial to increasing the ratio of fracture failure and improving rock-breaking efficiency. Laboratory drilling tests show that the cross-cutting PDC bit can create mesh-like bottom-hole features. Drilling contrast experiments show that a mesh-like bottom-hole pattern can be obtained by using the cross-cutting PDC bit, of which the ROP is obviously higher than that of the conventional bit when drilling in sandstone or limestone formation. Meanwhile, the influence of deviation angle, weight on bit, and rock properties on cutting efficiency of the cross-cutting PDC bit are studied.

Novel low Ag-content Sn–Ag–Cu–Sb–Al solder alloys with enhanced elastic compliance and plastic energy dissipation ability by applying rotating magnetic field

The main scope of this research is to investigate the impact of rotating magnetic field (RMF) on the physical properties of the Sn–0.5Ag–0.5Cu–2.0Sb–0.1Al (SAC0505SbAl) solder alloy. The application of RMF during molten alloy cooling showed prominent effect on the morphology, thermal properties, and the consequent mechanical characteristics. It was shown that the dendritic morphology was changed from columnar dendrites to equiaxed grains with the application of RMF. In addition, RMF processing modified the eutectic phases in the alloy matrix. These notable modifications have resulted in a substantial increase in ductility (~ 30%) with a slight decrease in tensile parameters (UTS and YS). Such effects could enhance elastic compliance and plastic energy dissipation ability of solder alloys, which plays superbly fundamental function in drop-impact reliability. Differential scanning calorimetry (DSC) analysis reveals that significant decrease in pasty range (from 10.8 to 7.5 °C) and undercooling (from 13.1 to 9.0 °C) was attained after applying RMF. The stress exponent (n), the activation energy (Q), and deformation mechanism of the SAC0505SbAl alloy processed with and without RMF were discussed in detail. The obtained results are certainly expected to fill the knowledge gap about the behavior of these recently developed solder alloys under the effect of RMF that are potential alternatives as Pb-free interconnecting material in microelectronic packaging industry.

Numerical Study on Seismic Response of Steel Storage Racks with Roller Type Isolator

This research evaluates the effectiveness of using a roller-type base isolation device with tensile strength in reducing the dynamic response of industrial steel storage racks. These were subjected to a seismic input acting separately in both directions of the structure. The seismic record obtained from the earthquake that occurred in Llolleo, Chile, on 3 March 1985, was used as input. This earthquake was scaled in the frequency domain, adjusting its response spectrum to coincide with the design spectrum required by NCh2745. In the calculations of this spectrum, the most hazardous seismic zone (zone 3) and soft soil (soil III) that amplifies the effect of the low frequencies of the earthquake were considered. These frequencies are the ones that have the most affect on flexible structures such as high racks and systems with base isolation. Numerical time-history analyses were performed in fixed base racks and base isolation racks. In both cases, the models include semi-rigid connections with capacity for plastic deformation and energy dissipation. Parametric analyses were carried out considering the most relevant variables, using an algorithm programmed in MATLAB software. The maximum relative displacement, maximum basal shear load, and maximum absolute floor acceleration were considered as responses of interest. The results showed the effectiveness of using the base isolation device by reducing the absolute accelerations between approximately 75% and 90%, compared to the same fixed rack at its base. This makes it possible to reduce the vulnerability of the stored load to overturn under the action of a severe earthquake.

A New Blast Absorbing Sandwich Panel with Unconnected Corrugated Layers—Numerical Study

The need for more effective defence systems is of critical importance because of the rising risk of explosive attacks. Sandwich panels are used as plastically deforming sacrificial structures, absorbing blast wave energy. To the authors’ knowledge, the blast behaviour of sandwich panels with connected (welded/bolted/riveted) corrugated layers has been well covered in literature. Hence, the aim of this numerical study was to develop new, easy-to-build, non-expensive, graded sandwich panel with ‘unconnected’ corrugated layers that can be used as a multipurpose sacrificial protective structure against wide range of blast threats. The proposed sandwich panel is composed of six unconnected aluminium (AL6063-T4) core layers encased in a steel (Weldox 460E) frame with 330 × 330 × 150 mm overall dimensions. The numerical analysis was conducted using Abaqus/Explicit solver. First, the performance of four different nongraded layer topologies (trapezoidal, triangular, sinusoidal, and rectangular) was compared, when subjected to ~16 MPa peak reflected over-pressure (M = 0.5 kg of TNT at R = 0.5 m). Results showed that the trapezoidal topology outperformed other topologies, with uniform progressive collapse, lower reaction force, and higher plastic dissipation energy. Then, the trapezoidal topology was further analysed to design a ‘graded’ sandwich panel that can absorb a wide range of blast intensities (~4, 7, 11, 13, and 16 MPa peak reflected over-pressures) by using a (0.4, 0.8, 1.2 mm) stepwise thickness combination for the layers. In conclusion, the superior performance of the proposed sandwich panel with unconnected graded layers can be considered as a novel alternative to the conventional costly laser-welded sandwich panels. Applications of the new solution range from protecting civil structures to military facilities.

A study on energy distribution law of frame structure across ground fissure

In order to study the frame structure energy dissipation mechanism on the ground, a 3x3 span 5-story frame structure was used as the research background, and a shaking table test with a scale ratio of 1:15 was designed. Based on the prototype structure, a finite element model based on ABAQUS is established. The correctness of the finite element model is verified by experimental comparison. On this basis, the plastic energy dissipation and damping energy consumption of the structural beam and the plastic energy dissipation law of the column are analyzed. The weak part of the structure of the trans-ground fissure structure under energy conversion is found. This study provides a reference for the arrangement of energy-consuming devices in seismic design and disaster prevention and mitigation design for similar structural engineering.

Temperature Effect on the Impact Characteristics of Mine Ring Chain under Different Working Conditions

The effect of temperature on the impact characteristics of the ring chain under different working conditions was investigated with ABAQUS simulation, the curves were fitted with MATLAB, and the results were experimentally verified. The temperature has little effect on minimum steady-state stress. The friction energy dissipation has three polynomial temperature relations under heavy-load start-up, and its dissipation does not vary at fluctuating loads. Under two working conditions, the plastic energy dissipation and internal energy increase linearly with temperature; at abrupt load variations, those energies increase with the tendency to stabilization. This method is of great significance for improving the initial characteristics of a scraper conveyor, variable-load operations, and design optimization of the ring chain.