Axial Impact Load of a Concrete-Filled Steel Tubular Member with Axial Compression Considering the Creep Effect

The dynamic loads acting on concrete-filled steel tubular members under axial impacts by rigid bodies were studied herein by FEM. The whole impact process was simulated and the time history of the impact load was obtained. The effects of eight factors on the axial impact load were studied; these factors were the impact speed, mass ratio, axial pressure ratio, steel ratio, slenderness ratio, concrete strength, impact position, and boundary conditions. Besides this, the effects of concrete creep on the impact load were also considered by changing the material parameters of the concrete. The results show that axial impact load changes with time as a triangle. The peak value of impact load increases and the impact resistance improves with the growth of the axial pressure ratio, steel ratio, slenderness ratio, and concrete strength after creep occurs. As the eccentricity of the axial impact acting on a concrete-filled steel tubular member increases, the peak value of the impact load decreases. The enhancement of constraints at both ends of the member can improve the impact resistance. The creep reduction coefficients for the peak axial impact load of a concrete-filled steel tubular member under axial compression and considering the creep effect over 6 months and 30 years are 0.60 and 0.55, respectively. A calculation formula for the peak value of impact load was suggested based on the existing formula, and its accuracy was proved by finite element calculation in this study.

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Influence of Incremental Impact on the Damage of Coal-Rock under Unidirectional Constraint

Advances in Civil Engineering ◽

10.1155/2019/3915689 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Hongbao Zhao ◽

Huan Zhang ◽

Jinyu Li ◽

Nansong Ju ◽

Zhijie Wen

Keyword(s):

Impact Load ◽

Damage Model ◽

Impact Resistance ◽

Cumulative Damage ◽

Axial Pressure ◽

Loading Test ◽

Damage Degree ◽

Coal Rock ◽

The Impact ◽

Pendulum Impact

Taking the briquette sample as research object, the influence of the incremental impulse (momentum) on the damage of coal-rock under different uniaxial axial pressure was studied by using the self-developed pendulum impact dynamic loading test device, cooperating with the ultrasonic detection device. Meanwhile, the influence of constant impulse on the damage degree of coal-rock was compared. The results show that the damage degree of coal-rock increases with the increase of the impulse, and the damage fitting curve is upward concave, indicating that the coal sample tends to accelerating failure. Moreover, with the increase of axial pressure, the variation gradient of the damage degree of coal-rock tends to moderate and the cumulative damage degree decreases under the same impulse, and the impact resistance of coal-rock increases. When the impulse is constant, the damage degree of coal-rock increases with the number of impact, and the damage curve is upward convex, indicating that coal-rock has a tendency to slow down the damage. The cumulative damage degree of coal-rock decreases with the increase of axial pressure, and the number of impact needed to destroy coal-rock is increased. In addition, the damage model of coal-rock was proposed, and the criterion of coal-rock damage was obtained, which shows that the damage degree of coal-rock increases with the increase of impact load and decreases with the increase of static axial load.

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Impact Resistance Analysis and Optimization of Variant Truss Beam Structure Based on Material Properties

Materials ◽

10.3390/ma14195847 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5847

Author(s):

Xiaohao Li ◽

Junqi Pan ◽

Xingchen Zhou

Keyword(s):

Simulation Analysis ◽

Impact Load ◽

Impact Resistance ◽

Structure Design ◽

Response Surfaces ◽

Optimization Strategy ◽

Buffer Effect ◽

Characteristic Analysis ◽

Beam Structure ◽

The Impact

In order to meet the increasing application requirements with regards to structural impact resistance in industries such as mining, construction, aerospace engineering, and disaster relief and mitigation, this paper designs a variant truss beam structure with a large shrinkage ratio and high impact resistance. Based on the principle of the curved trajectory of scissor mechanisms, this paper conducts a finite element simulation analysis of the impact load on the truss beam structure, a theoretical analysis of the impact response and a relevant prototype bench-top experiment, completing a full study on the impact resistance mechanism of the designed variant truss beam structure under the impact load. In the paper, the buffer effect of the external load impact on the variant truss beam structure is analyzed from the perspective of the energy change of elastic–plastic deformation. This paper proposes an optimization strategy for the variant truss beam structure with the energy absorption rate as the optimization index through extensive analysis of the parameter response surfaces. The strategy integrates analyses on the response characteristic analysis of various configuration materials to obtain an optimal combination of component parameters that ensures that the strength of the truss beam structure meets set requirements. The strategy provides a feasible method with which to verify the effectiveness and impact resistance of a variant truss structure design.

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Experimental Study on Axial Impact Mitigating Stick-Slip Vibration with a PDC Bit

Shock and Vibration ◽

10.1155/2021/8897283 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Yong Wang ◽

Hongjian Ni ◽

Yiliu (Paul) Tu ◽

Ruihe Wang ◽

Xueying Wang ◽

...

Keyword(s):

Impact Force ◽

Impact Load ◽

Similarity Theory ◽

Impact Frequency ◽

Stick Slip ◽

Axial Impact ◽

Pdc Bit ◽

Fluctuation Amplitude ◽

Rotary Speed ◽

The Impact

Stick-slip vibration reduces the drilling rate of penetration, causes early wear of bits, and threatens the safety of downhole tools. Therefore, it is necessary to study suppression methods of stick-slip vibration to achieve efficient and safe drilling. Field tests show that the use of downhole axial impactors is helpful to mitigate stick-slip vibration and improve rock-breaking efficiency. However, there are many deficiencies in the study of how axial impact load affects stick-slip vibration of a PDC bit. In this paper, based on the two-degrees-of-freedom spring-mass-damper model and similarity theory, a laboratory experiment device for suppressing stick-slip vibration of a PDC bit under axial impact load has been developed, and systematic experimental research has been carried out. The results show that the axial impact force can suppress the stick-slip vibration by reducing the amplitude of weight on bit and torque fluctuations and by increasing the main frequency of torque. The amplitude of impact force affects the choice of the optimal back-rake angle. The impact frequency is negatively correlated with the fluctuation amplitude of the rotary speed. When the impact frequency is greater than 100 Hz, the fluctuation amplitude of the rotary speed will not decrease.

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Impact Response of Hammerhead Pier Fibrous Concrete Beams Designed with Topology Optimization

Periodica Polytechnica Civil Engineering ◽

10.3311/ppci.16664 ◽

2020 ◽

Cited By ~ 3

Author(s):

Meivazhisalai Parasuraman Salaimanimagudam ◽

Covaty Ravi Suribabu ◽

Gunasekaran Murali ◽

Sallal R. Abid

Keyword(s):

Topology Optimization ◽

Concrete Beams ◽

Impact Load ◽

Impact Resistance ◽

Adaptive Mesh ◽

Impact Response ◽

Adaptive Meshing ◽

Repeated Impact ◽

Ductility Ratio ◽

The Impact

Reducing the weight of concrete beams is a primary (beyond strength and durability) concern of engineers. Therefore, this research was directed to investigate the impact response of hammerhead pier concrete beams designed with density-based method topology optimization. The finite element topology optimization was conducted using Autodesk fusion 360 considering three different mesh sizes of 7 mm, 10 mm, and adaptive meshing. Three optimized hammerhead beam configurations; HB1, HB2, and HB3, respectively, with volume reductions greater than 50 %. In the experimental part of this research, nine beams were cast with identical size and configuration to the optimized beams. Three beams, identical to the optimized beams, were tested under static bending for verification purposes. In comparison, six more beams, as in the preceding three beams but without and with hooked end steel fibers, were tested under repeated impact load. The test results revealed that the highest flexural capacity and impact resistance at crack initiation and failure were recorded for the adaptive mesh beams (HB3 and HB3SF). The failure impact energy and ductility ratio of the beam HB3SF was higher than the beams HB1SF and HB2SF by more than 270 %. The results showed that the inclusion of steel fiber duplicated the optimized beam’s impact strength and ductility several times. The failure impact resistance of fibrous beams was higher than their corresponding plain beams by approximately 2300 to4460 %, while their impact ductility ratios were higher by 6.0 to 18.1 times.

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Experimental Investigation on Relations Between Impact Resistance and Tensile Properties of Cement-Based Materials Reinforced by Polyvinyl Alcohol Fibers

Applied Sciences ◽

10.3390/app9204434 ◽

2019 ◽

Vol 9 (20) ◽

pp. 4434

Author(s):

Ju Zhang ◽

Pucun Bai ◽

Changwang Yan ◽

Shuguang Liu ◽

Xiaoxiao Wang

Keyword(s):

Polyvinyl Alcohol ◽

Tensile Properties ◽

Impact Load ◽

Impact Resistance ◽

Crater Diameter ◽

Cement Based Materials ◽

Weight Test ◽

Ultimate Failure ◽

Drop Weight Test ◽

The Impact

Cement-based material is brittle and is easily damaged by an impact load with a few blows. The purpose of this paper is to study the relations between the impact resistance and tensile properties of cement-based materials reinforced by polyvinyl alcohol fiber (PVA-FRCM). A drop-weight test and uniaxial tension test were performed. The relations were studied based on the experimental results, including the relation between the blow number and the tensile stress at the first visible cracking (σc) and the relation between the blow number and the tensile strain at the ultimate failure (εf). Results showed that the blow number for the first visible crack for disc impact specimens increases obviously with the increase of σc of slab specimens. The crater diameter and blow number for ultimate failure of the disc specimens increase with the increase of εf of slab specimens. For the PVA-FRCM specimens with larger σc and εf, much more blows are needed to cause both the first visible crack and ultimate failure. Polyvinyl alcohol fibers can reinforce impact resistance and tensile properties of cement-based materials.

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Experimental Investigation on the Impact Resistance of Carbon Fibers Reinforced Coral Concrete

Materials ◽

10.3390/ma12234000 ◽

2019 ◽

Vol 12 (23) ◽

pp. 4000 ◽

Cited By ~ 2

Author(s):

Bing Liu ◽

Jingkai Zhou ◽

Xiaoyan Wen ◽

Jianhua Guo ◽

Xuanyu Zhang ◽

...

Keyword(s):

Weibull Distribution ◽

Carbon Fibers ◽

Impact Test ◽

Concrete Strength ◽

Impact Resistance ◽

Initial Crack ◽

Drop Weight ◽

Weight Impact ◽

The Impact ◽

Two Parameter

In this study, the impact resistance of coral concrete with different carbon fiber (CF) dosages subjected to drop-weight impact test was investigated. For this purpose, three concrete strength grades (C20, C30, C40) and six CF dosages (0.0%, 0.3%, 0.6%, 1.0%, 1.5%, and 2.0% by weight of the binder) were considered, and a total of 18 groups of carbon fibers reinforced coral concrete (CFRCC) were cast. For each group, eight specimens were tested following the drop-weight impact test suggested by CECS 13. Then, the two-parameter Weibull distribution theory was adopted to statistically analyze the variations in experimental results. The results indicated that the addition of CFs could transform the failure pattern from obvious brittleness to relatively good ductility and improve the impact resistance of coral concrete. Moreover, the impact resistance of CFRCC increases with the CF dosage increasing. The statistical analysis showed that the probability distribution of the blow numbers at the initial crack and final failure of CFRCC approximately follows the two-parameter Weibull distribution.

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Experimental Study on Mechanical Property of Steel Reinforced Concrete Short Columns of T-Shaped

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.340-341.1121 ◽

2007 ◽

Vol 340-341 ◽

pp. 1121-1126

Author(s):

Zhe Li ◽

Xiao Feng Zhang ◽

Yan Feng Zhao ◽

De Fa Wang

Keyword(s):

Shear Strength ◽

Mechanical Performance ◽

Pressure Ratio ◽

Large Degree ◽

Seismic Intensity ◽

Axial Pressure ◽

Displacement Ductility ◽

Short Columns ◽

Test Study ◽

The Impact

The horizontal press performance of column is deteriorated because of special-shaped section. Moreover, because the antiseismic performance of columns is worse, it is only used in regions where seismic intensity is lower. So the main problem is to enhance the ductility. This test study on mechanical performance has been carried out through fourteen SRCTSSC and RCTSSC. The study focuses on the impact of test axial pressure ratio(nt), hooped reinforcement ratio(ρv), shear span ratio(λ) and steel ratio(ρss) to the shear strength and the antiseismic performance of SRCTSSC. It can be concluded that the shear strength of SRCTSSC is increasing with the increasing of nt and ρss , but the degree of increasing is small when nt is a certainty value, and that the shear strength of SRCTSSC is decreasing with increasing of λ; The shear resistance formula of T-shaped column is derived through tests, the calculated results are in correspondence with those of the tests. It also can be concluded that the hysteretic loops of the SRCTSSC are full and the hysteretic behaviors are improved and that the displacement ductility is increasing with increasing of ρv and ρss , but decreasing with the increasing of nt and the degree of variety in high axial pressure ratio is larger than in low axial pressure ratio. If steel bars are added, the shear strength and displacement ductility of SRCTSSC is increased in a large degree, and the capacity of energy dissipation is also enhanced. This test, for applying the special-shape column to higher intensity region, has the certain instructive significance.

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Effects of Water-Borne Polyurethane on Calcium Silicate Hydrate and Toughness of Properties of Cementitious Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.619.545 ◽

2012 ◽

Vol 619 ◽

pp. 545-552

Author(s):

Bei Ding ◽

Xia Zhang ◽

Dong Liang Zhou ◽

Chan Wen Miao

Keyword(s):

Mechanical Performance ◽

Concrete Strength ◽

Harmful Effect ◽

Impact Resistance ◽

29Si Nmr ◽

Size Change ◽

Block Polymer ◽

Chain Conformations ◽

The Impact ◽

Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations-water-borne polyurethane (PUA) was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The interactions between Water-borne PUA and C-S-H nanostructure, which include intercalation and the polymerization degree of C-S-H silicate chains, were studied by small angle X-ray diffraction spectra and 29Si NMR spectra, respectly. The influences of water-borne PUA on mechanical performance of C-S-H were investigated experimentally. The small XRD results show that no evidence is observed for any fundamental size change in the C-S-H particles that have been formed in the presence of polymer. The NMR results indicate that there is a significant increase in the Q2/Q1 ratio ranging from 0.5 for pure C-S-H to 2.2 for PUA-C-S-H, respectively. The degree of silicate polymerization increases from 3.0 for pure C-S-H to 6.4 for PUA-C-S-H by calculation. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively.The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber.

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Numerical Simulation of Modified Rubberized Concrete Block Under Impact Loads

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1200/1/012022 ◽

2021 ◽

Vol 1200 (1) ◽

pp. 012022

Author(s):

T Y Pei ◽

S N Mokhatar ◽

N A N A Mutalib ◽

S J S Hakim

Keyword(s):

Energy Absorption ◽

Impact Load ◽

Concrete Strength ◽

Constitutive Models ◽

Numerical Procedure ◽

Concrete Block ◽

Crumb Rubber ◽

Impact Loads ◽

Rubberized Concrete ◽

The Impact

Abstract Rubberized concrete was innovated by many researchers to enhance energy absorption under impact load and by reusing scrap tires. Thus, this research was aims to develop the numerical procedure using the Finite Element Method (FEM) to simulate modified rubberized concrete under impact loads and predict its energy absorption under different impact loads. Three existing constitutive models: Concrete Damage Plasticity (CDP), Drucker-Prager (DP), and Modified Drucker-Prager Cap (MDPC) available in ABAQUS software were used to replicate the rubberized concrete with 10% of Rice Hush Ash (RHA) as cement substitution and different percentages (0%, 5%, 10%, 15%, and 20%) of crumb rubber as sand replacement. All three models produced successful FEM results with reasonable modelling assumption, and the CDP model was more effective in simulating rubberized concrete under impact to predict energy absorption than DP and MDPC models. Further, it was concluded that crumb rubber could enhance the energy absorption of concrete. Generally, the energy absorption of the concrete increased as the crumb rubber increase. However, the strength decreased as the crumb rubber increased, but 10% of RHA in concrete mix can maintain the concrete strength. Overall, this study reveals that FEM incorporated with the CDP model is able to predict the impact response of modified crumb rubber as an application of concrete road barrier.

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DYNAMIC IMPACT WEAR AND IMPACT RESISTANCE OF W-B-C COATINGS

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2020.27.0037 ◽

2020 ◽

Vol 27 ◽

pp. 37-41

Author(s):

Josef Daniel ◽

Jan Grossman ◽

Vilma Buršíková ◽

Lukáš Zábranský ◽

Pavel Souček ◽

...

Keyword(s):

Impact Test ◽

Impact Load ◽

Protective Coatings ◽

Impact Resistance ◽

Impact Testing ◽

The Novel ◽

Test Results ◽

Dynamic Impact ◽

Impact Deformation ◽

The Impact

Coated components used in industry are often exposed to repetitive dynamic impact load. The dynamic impact test is a suitable method for the study of thin protective coatings under such conditions. Aim of this paper is to describe the method of dynamic impact testing and the novel concepts of evaluation of the impact test results, such as the impact resistance and the impact deformation rate. All of the presented results were obtained by testing two W-B-C coatings with different C/W ratio. Different impact test results are discussed with respect to the coatings microstructure, the chemical and phase composition, and the mechanical properties. It is shown that coating adhesion to the HSS substrate played a crucial role in the coatings’ impact lifetime.

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