Tension Impact Tests Research Articles

Rapid evaluation of trade-offs between strength and impact toughness of wheel steels by instrumented spherical indentation test

In this paper, an improved size-independent instrumented spherical indentation test (ISIT) method was proposed to determine tensile strength and fracture toughness on wheel rims of two different types of wheel steels. Additionally, Charpy impact specimens were taken from three specific positions on the wheel rims and subjected to standard Charpy impact testing. The resulting Charpy impact energy (CVN) were matched with the fracture toughness measured by ISIT (KIc,IT) at the same positions. There was a clear linear correlation between CVN and the square of KIc,IT, which was consistent with the established relationship between both properties as determined by conventional Charpy impact and compact tension tests. Therefore, we expanded the ISIT method to study the impact of cooling rates on the variation of yield strength and Charpy impact energy across the wheel rim. To accomplish this, we designated additional testing points on the wheel rim using the ISIT method. The investigation found trade-offs between strength and impact toughness of wheel steels under different cooling rates. The above findings demonstrated the effectiveness of using the ISIT method, which facilitated high-resolution fracture toughness measurement, to establish accurate correlation between CVN and fracture toughness of wheel steels. Moreover, this ISIT method can be employed to regulate heat treatment of material properties to meet specific application requirements.

Experimental and finite element analysis of Charpy impact, uniaxial tension and bending test of spin‐arc welded carbon steel 1018 plate

AbstractSpin‐arc welding process emerged as a continuation of gas metal arc or flux‐cored arc welding process, making use of filler wire and fuse plates of higher thickness with less welding defects. In this process, the filler wire is made to rotate along a central axis with a fixed diameter and frequency, thereby reducing the number of weld runs to join thick plates and resulting in increased productivity and less consumption of filler wire. American iron and steel institute carbon steel 1018 is a low carbon steel used primarily in rugged environments and is known for its excellent weldability and finds application in spacers, mounting plates, fixtures, carburized parts and machine parts. Present work aims to provide insight on experimental and finite element analysis of carbon steel 1018 (base and spin arc weld metal) specimens subjected to Charpy impact and uniaxial tension test. In order to verify the weld quality under bending load, a comparative study among experimental and finite element analysis of bending test is also performed. The finite element analysis results of Charpy impact, uniaxial tension and bending test are validated with experimental outcomes.

Experimental Evaluation of the Effect of Silica Fume on Compressive, Tensile Strength, Abrasion Resistance, Slump and Impact Test and Water Permability Coefficient of Concrete

Abstract The use of various additives (admixtures) in concrete and cement products has been considered by various researchers in recent years. Microsilica (Silica fume) can also be considered as one of the most widely used additives (admixtures) in this section. In this study, 120 concrete specimens were constructed using a mix design based on ACI in the laboratory with an overview of records and advantages of using microsilica in concrete. The microsilica used in concrete specimens has been considered 2%, 5.5% and 7.5% by weight of cement. Finally impact permeability, tension and uniaxial compressive strength tests were done on concrete specimens and their mechanical properties were evaluated. The results show that microsilica improves the mechanical properties of concrete. The results also show that the use of microsilica in ordinary concrete has a very positive effect in controlling the surface cracks and increasing some strength parameters such as tensile and compressive strength of concrete.

Mechanical characteristics and thermal behaviours of polylactide blend films: influence of nucleating agent and poly(butylenes adipate-co-terephthalate)

Polylactide (PLA) blend films with poly(butylenes adipate-co-terephthalate) (PBAT) and a nucleating agent were prepared by the melt compounding technique. Thermal stability of the PLA decreased with added nucleating agent; in contrast, the decomposition temperature increased with the presence of PBAT. In addition, the differential scanning calorimetry thermograms demonstrated that the heterogeneous nucleation and cold crystallisation processes of the PLA blend films were accelerated.The influence of the type and level of the nucleating agent and the presence of PBAT on the tensile properties, impact resistance, thermal stability and non-isothermal crystallisation behaviours of the PLA blend films were investigated. Both the PLA/nucleating agents and the PLA/PBAT/nucleating agent blends showed significant effects from the changes in the nucleation process on their tensile properties, impact toughness and thermal behaviour. Furthermore, the impact energy that the PLA blends absorbed during the entire impact tension test was obviously enhanced by the increased content of the nucleating agent.

G0300103 緻密骨衝撃引張試験方法の確立(出力不良原因の検討)

Now, aging is progressing all over the world. Therefore, prevention of bone fracture is required. In order to do it, it is necessary to analyze deformation behavior of bone when a person falls down. However, the mechanical properties of bone have not been investigated when impact load acts on it. This study focuses on impact tension property of bone and constructs impact tension test equipment as a purpose. The theory of the split Hopkinson stick method was applied to the impact tension test. But various problems have occurred on the impact tension test equipment. The fixed method of lead wires produced a wave problem at Gauge 2 and this problem was improved by using straws. The biggest problem is occurred at Gauge 1, which is unstable output from Gauge 1. But the confirmation of this problem is difficult by experimental method. So, the relationship between the incident stress and the influence of collision of leaned striker with Flange were clarified by numerical analysis.

A novel integrated tension-compression design for a mini split Hopkinson bar apparatus

A miniature integrated Split Hopkinson Bar (SHB) apparatus based on an innovative three-loading bar technique and a multi-stage electromagnetic driving technique was developed for both impact compression and tensile tests. The design principles of these techniques and the whole structure of this new device are discussed in detail. Compared to the traditional SHB apparatus which has a single-function, this new device can realize the integration of compression and tensile tests. Furthermore, due to the application of the electromagnetic driving technique, the whole structure of the SHB apparatus can be miniaturized with good reproducibility, reliability, and no noise, making it easier to move to different locations without the need for heavy gas launching systems used for some specialist tests. Under both impact compression and tensile conditions, a series of verification experiments were carried out on 2A12 aluminum alloy, proving that the new apparatus can conduct impact tension and compression tests for small specimen with high accuracy and reliability. The dynamic behavior of electrodeposited nickel fabricated by micromachining was investigated at a high strain rate of 1.2 × 10(4) s(-1) using this new setup, the obtained results indicating that the Lithographie Galanoformung Abformung (LIGA) deposited nickel is very sensitive to strain rate.

Testing and Evaluation of Mechanical Properties for Anisotropic Engineering Materials with Varied Loads

This paper is aimed at investigating the influence of load-bearing style on the mechanical behavior of anisotropic engineering materials. The study on elastic constants and failure forms of materials will be presented under different loading condition. Firstly, the mechanical properties of unidirectional holey laminated materials are discussed based on the uniaxial tensile tests. The equivalent elastic modulus, Poisson’s ratio and shear modulus are obtained, and the pattern and mechanism of failure are analyzed. Then, the biaxial tensile tests are carried out for PVC orthotropic membrane materials with different stress ratio between the warp and weft direction. A comparison of limit strengths under biaxial loadings is given with that in uniaxial loading case. Finally, the dynamical behaviors of shape memory alloy (SMA), iron wire, and rubber composite as well as compound rubber are studied respectively by impact-tension tests. The failure forms, energy dissipation ratio and impact-tension toughness of materials are analyzed. It is shown that the mechanical properties and failure pattern of anisotropic materials have much to do with the load-bearing styles. It agrees well with actual properties of anisotropic material used in engineering structures.

Parameter estimation of a rate-dependent damage constitutive model for damage-tolerant brittle composites by Self-OPTIM analyses

This article demonstrates a novel parameter identification of a rate-dependent damage constitutive model using self-optimizing inverse method. In the self-optimizing inverse method, an implicit–explicit objective function is formulated as a function of two sets of full-field stresses/strains (implicit non-measurable variables) from two nonlinear finite element analyses, that is, force-driven and displacement-driven simulations, respectively, and global boundary displacements and forces (explicit measurable variables) from experimental tests. The self-optimizing inverse method can self-correct the damage parameter set through optimization procedures referring to global responses measured in laboratory tests. A micromechanics and fracture mechanics based damage constitutive law that accounts for the microcrack nucleation and growth is adopted. Synthetic data from impact tension test simulations were used to demonstrate successful performances of the self-optimizing inverse method in identifying the nonlinear constitutive and damage-related parameters. Comparative studies were conducted using two different optimization techniques – the simplex method and the steady-state genetic algorithm. The identified parameters proved to be identical to the reference values. Finally, in order to further verify the inverse identification method, self-optimizing inverse method analyses were conducted to identify the damage parameter set based on real experimental data from impact tension tests at different strain rates.

Investigation of tensile deformation behavior of PC, ABS, and PC/ABS blends from low to high strain rates

This paper experimentally studies the tensile deformation behavior of poly- carbonate (PC), acrylonitrile-butadiene-styrene (ABS), and PC/ABS blends (with the blending ratios of PC to ABS being 80:20, 60:40, 50:50, and 40:60) from low to high strain rates. Using the universal MTS-810 machine and the split Hopkinson tension bar (SHTB) testing system, the quasi-static and impact tension tests are carried out at the room temperature. The curves of the true stress and the true strain are obtained. The deformation behaviors of PC, ABS, and PC/ABS blends are characterized in detail. The linear relationship between the strain rate and the yielding stress is given.

Effect of Normalizing and Hardening on Mechanical Properties of Spring

This study was carried out to investigate the effect of heat treatment (Normalizing and Hardening) on the mechanical properties of springs. The springs were made from mild steel rod having a diameter of 6 mm, a total of 15 springs were made. The springs were then subjected to various heat treatment processes which included; normalizing, hardening and tempering. The heat treated springs were then subjected to various test in other to determine their mechanical properties, these included; impact toughness test, hardness test and tension test. The normalized spring had more strength, was harder and was much tougher than both the annealed and as received springs. The water quenched springs were the hardest of all the heat treated springs, were very brittle and had the lowest percentage elongation. Their strength was also lower than that of the normalized and as received springs. The water quenched and tempered springs had better mechanical properties required for spring making, they had the optimum combination of hardness, strength and toughness when compared with the other heat treated springs.

Pulse current treatment effect on the strength of reinforcing steel and its weld joint under impact loading

We present results of static and impact tension tests of as-received reinforcing steel specimens, specimens with weld joints in their test portion, as well as specimens pretreated by high-density pulse current. As test results demonstrate, an increased strain rate enhances strength, and the pulse current treatment greatly influences the strength and plasticity of a defect-containing weld metal under static and impact tension.

Effects of strain-rate and pre-fatigue on tensile properties of laser welded joint of high strength steel plates

The impact tensile properties of laser welded butt joints of two kinds of high strength steel plates with the tensile strength level of 590 MPa and 780 MPa (denoted by HR590 and HR780, respectively), were investigated using split Hopkinson bar tensile testing apparatus. Impact tension tests for the joint specimens pre-fatigued were also carried out to examine the effect of pre-fatigue. There were no significant effects of strain-rate and pre-fatigue on the dynamic and quasi-static tensile strength of laser welded butt joints. However, the decrease in the elongation of HR780 welded joints subjected high cycle pre-fatigue was observed only at a high strain-rate. From the observation of fracture surface, it was found that the decrease in the elongation may be caused by a number of damages due to the combination of high cycle pre-fatigue and high strain-rate.

地震時の衝撃上下動による基礎杭破壊形態とモルタルを用いた基礎的衝撃実験

This paper presents experimental investigations on particular failure patterns of foundation piles found in Hyogo-ken Nambu earthquake that were probably induced by seismic up-down vibrations. Impact tests on cylindrical mortar specimens were conducted in different loading modes. Vertical splitting failure was observed in static compression tests whereas horizontal tensional fracture occurred in static tension tests and impact tension tests. Depending on the level of impact energy, failure patterns in impact compression tests were found varying from cone splitting failure to X-shape shearing failure to cone shearing failure to 45-degree shearing failure, and to horizontal tensional fracture due to reflection stress wave.

板状試験片の衝撃引張試験法の検討

This study is concerned with the split Hopkinson bar method for tension test of strip specimens. The split Hopkinson bar method (SHB) has been used for impact tests such as compression and shearing, and is currently modified for tension test. It is demanded that the impact tensile behaviour of high-tensile strength steel plates is made clear in the design of light-weight and high stiffness automotive parts for weight reduction in materials. However, the method of impact tension test using the SHB has not been established because the testing conditions such as specimen geometry and fastening are quite different from them in compression test. In this paper, the characteristics of the SHB method for tension test are examined using by some experiments and numerical simulations. Particularly the appearance of initial peak in stress-strain curves like an increase of yield point is discussed from the viewpoint of the specimen geometry and the attachment of a specimen and stress bars with screws. It is found that the fastening method affects strongly the responses of stress waves measured on an output bar and then causes the virtual peak in the initial portions of stress-strain diagram.

110 Impact Tensile Properties of Friction Welded Butt Joints between 6061 Aluminum Alloy and Type 304 Stainless Steel

The tensile strength and energy absorption of dissimilar metal friction welds between 6061 Al alloy and Type 304 stainless steel at high rates of loading are determined using the split Hopkinson bar. Round tensile specimens machined from as-welded butt joints of 12 mm diameter are used in both static and impact tension tests. Friction welding is conducted using a brake type friction welding machine under two different welding conditions. The effects of welding parameters and loading rate on the tensile properties of friction welded butt joints are investigated. It is demonstrated that the tensile properties are greatly affected by the welding conditions, and are slightly enhanced with increasing loading rate. Macroscopic observations reveal that the tensile fracture mode of friction welded butt joints varies with loading rate, depending on the welding conditions. Microhardness measurements are performed to examine the extent of the heat-affected zone (HAZ) across the weld interface. The slight enhancement in the tensile properties of friction welded butt joints with increasing loading rate is due to the strain rate dependence of the thermally-softened 6061 Al alloy base material.

Stress‐strain characteristics of S15C carbon steel friction‐welded butt joints under impact tensile loading

Stress-strain characteristics of S15C carbon steel friction welded butt joints under impact tensile loading are evaluated using the split Hopkinson bar. Round tensile specimens machined from as-welded butt joints of 13 mm diameter are used in both static and impact tension tests. Friction welding is carried out using a brake type friction welding machine under fixed welding conditions. The effect of strain rate up to e≅700/s on the tensile stress-strain characteristics of both friction welded butt joints and a base material (S15C carbon steel) is studied. It is shown that the flow stress for friction welded butt joints is always higher than that for the base material at low and high rates of strain, but the former are less sensitive to strain rate than the latter. Microhardness measurements are conducted to examine the extent of the heat-affected zone (HAZ) across the weld interface. Metallographic examination reveals that there are zones of different grain structure through the weld region. The increase in the flow stress for friction welded butt joints is attributed to the presence of a locally-hardened region within the HAZ.

衝撃引張荷重下におけるＳ１５Ｃ炭素鋼摩擦圧接継手の応力‐ひずみ特性

Stress-strain characteristics of S15C carbon steel friction welded butt joints under impact tensile loading are evaluated using the split Hopkinson bar. Round tensile specimens machined from as-welded butt joints of 13 mm diameter are used in both static and impact tension tests. Friction welding is carried out using a brake type friction welding machine under fixed welding conditions. The effect of strain rate up to e≅700/s on the tensile stress-strain characteristics of both friction welded butt joints and a base material (S15C carbon steel) is studied. It is shown that the flow stress for friction welded butt joints is always higher than that for the base material at low and high rates of strain, but the former are less sensitive to strain rate than the latter. Microhardness measurements are conducted to examine the extent of the heat-affected zone (HAZ) across the weld interface. Metallographic examination reveals that there are zones of different grain structure through the weld region. The increase in the flow stress for friction welded butt joints is attributed to the presence of a locally-hardened region within the HAZ.

Dynamic J-R curves and tension-impact properties of AISI 308 stainless steel weld

In this paper, instrumented tension-impact (dynamic tensile) and instrumented Charpy impact test results for AISI 308 stainless steel welds at room temperature are reported. A few Charpy specimens precracked to a/W (crack length to width ratio) ratios of 0.42 to 0.59 were also tested. Dynamic yield strength obtained from tension-impact test agrees well with that from Charpy V-notch specimens. The strain rates obtained during the tension-impact test are compared with the various estimates of strain rates for V-notch and precracked Charpy specimens. A variation of the compliance changing rate method was necessary for determining the crack initiation point while crack growth was determined by power law key-curve procedure. J-R curves thus obtained from Charpy (precracked and V-notch) specimens are compared with those computed using handbook procedures using dynamic tensile results.

Toughness of SMI-modified ABS alloys and the associated deformation behavior

The mechanical toughness of modified ABS (acrylonitrile–butadiene–styrene) alloys was evaluated using Izod impact, tensile, and compact tension tests. The modified ABS alloys contain 20 wt % of styrene–N-phenylmaleimide (SMI) that is added to enhance the thermal resistance of the ABS. In this study, the effects of matrix composition, rubber/matrix adhesion, and rubber particle structure on the alloy toughness were investigated. Results from the tensile test and Izod impact test ranked the alloys in an order that is different from that given by KIi (stress intensity factor for crack initiation), measured from compact tension specimens. This is due to the difference in energy-absorption characteristics for crack initiation and crack growth. The conclusion is supported by optical micrographs on the deformation zone size. The microdeformation behavior of the alloys was examined using transmission electron microscopy (TEM), which revealed different rubber-toughening mechanisms between Izod and tensile specimens. The former contains numerous extensive crazes, while the latter, only a very few short crazes, except in regions within a few micrometers from the fracture surface. The dominant matrix deformation mechanism for the tensile specimens is believed to be shear deformation. Another interesting observation from the study is rubber particle cavitation, commonly observed in tensile specimens and Izod specimens with solid rubber particles; it did not occur in the Izod specimens containing salami-type rubber particles. This is attributed to the salami structure that increased the straining rate for the rubber phase, leading to ductile–brittle transition of the rubber. The transition to brittle deformation of the rubber phase prevented rubber particle cavitation. The microscopic examination indicated that toughening mechanisms by the rubber particles can be very different among the mechanical tests, which should be taken into account for the rubber toughening of polymers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1543–1553, 1999

Low-Cycle Impact Fatigue of SiC<SUB>w</SUB>/7475Al Composite

Important uses in the future for metal-matrix composites are in aerospace, weaponry, and high-speed power plants in which the inertial force produced by great acceleration is a load of high strain rate. Therefore close attention is given to the mechanical behavior of a composite at high strain rates. This paper reports a study of the behavior and mechanisms of a SiC w /7475 composite in low-cycle impact fatigue (LCIF). The LCIF and impact tension tests were conducted by using the push-pull impact fatigue apparatus developed by the authors, in which the loading assembly was actually a combination of a Hopkinson’s pressure bar and an extension bar. In the apparatus the trapezoidal stress wave loads were produced. The strain rates in specimens may reach 400 s -1 .The results show that for a SiC w /7475 composite, the strain-rate effects on yield stress, ductility, cyclic hardening and softening, δ e /2-N f relation, and transition life were slight. In low-cycle impact fatigue the cracks often initiated within or near the SiC particles, which mingled in the composite. The SiC w /7475 composite was found to be less ductile than its alloy matrix; in low-cycle fatigue brittleness appears. Therefore great attention must be given to the behavior of the composite when it is used as a structural material.