Impact Test Method Research Articles

Structural Identification of an Old Bridge by Multiple Reference Impact Test Method

Experimental data was collected for structural identification (St-Id) of an old bridge: (1) static displacement and strain measurements taken under proof-load level, and; (2) multi-reference impact test (MRIT) data from one of the spans of a three span, cast-in-place reinforced concrete (RC) T-beam Bridge. MRIT was used to generate the modal data for computation of modal flexibility and displacement profiles. The St-Id procedure used during this application was designed to mitigate epistemic uncertainty in the data interpretation process. Successful results from MRIT demonstrated the reliability of applications for bridge condition assessment based on impact testing.

IMPACT ABRASION OF HYDRAULIC STRUCTURES CONCRETE

Most of the abrasion damage is caused by the action of water-borne particles (silt, sand, gravel, and other solid) impacting and rolling against the concrete surface during hydraulic structure operation. In this paper solid-particle abrasion of concrete containing slag was studied. Experiments included use of river sand abrade of mean diameter ~ 0.6, 1.2, 2.5 and 5 mm, and sand content was 110, 230 and 340 kg per 1 m 3 of water, impacting at 30°, 45° and 90° to the concrete surface. And the waterborne sand flow impact test method was used. Test results show that the abrasion rate to be a strong function of erodent size and waterborne sand content. As the erodent size increased from 0.6 mm to 1.2 mm, 2.5 mm, then to 5mm, the abrasion rate of concrete increased from 100% to 217% and 367%. The waterborne sand content was 110, 230 and 340 kg/m 3 and the abrasion rate of concrete is 22-56 times of none sand water. Moreover, the abrasion rate of concrete impacted at 90° was higher than of that of 30°, 45° and 60°.

A new impact testing method for efficient structural flexibility identification

Traditional multi-reference impact testing (MRIT) has the merit of identifying not only the structural modal parameters but also structural flexibility. However, it requires a large number of sensors mounted on the entire structure which leads to expensive experimental costs. A new mobile impact testing method is proposed in this paper for a more efficient flexibility identification of bridges. In the proposed method, the structure under investigation is subdivided into smaller sub-structures which are tested independently. Then the experimental data collected from all sub-structures are integrated by taking the interface measurement as a reference for flexibility identification of the entire structure. The new impact testing method only requires limited instrumentation, thus it can be performed rapidly and efficiently. In particular, the signal processing procedure developed in the proposed method is able to identify the full flexibility matrix of the entire structure from the sparse FRF matrices of the sub-structures. Numerical and experimental examples studied successfully verify the effectiveness of the proposed method by comparing its results with those from the traditional MRIT method for structural flexibility identification and deflection prediction.

A novel high speed impact testing method for evaluating the low temperature effects of eutectic and lead‐free solder joints

PurposeThe purpose of this paper is to present a novel high speed impact testing method for evaluating the effects of low temperatures on eutectic and lead‐free solder joints. Interfacial cracking failure of Sn‐based and Pb‐free solders at subzero temperatures is of significant concern for electronic assemblies that operate in harsh environments.Design/methodology/approachThis paper presents a newly designed low temperature control system coupled with an Instron micro‐impact testing machine, which offers a package level test for solder bumps, and that is used at subzero temperature ranges as low as −40°C. This study examined the failure characteristics of 63Sn‐37Pb (Sn37Pb) and 96.5Sn‐3Ag‐0.5Cu (SAC305) solder joints at temperatures ranging from room temperature (R.T.) to −40°C, and at impact speeds of 1 m/s.FindingsThree types of failure mode were identified: M1 interfacial fracture with no residual solder remaining on the pad (interfacial cracking); M2 interfacial fracture with residual solder persisting on the pad (mixed mode failure); and M3 solder ball fracture (bulk solder cracking). The experimental results indicated that the energy to peak load for both types of solders decreased significantly, by approximately 35 percent to 38 percent when the test temperature was reduced from R.T. to −40°C. In addition, the peak load of the Sn37Pb solder joint increased noticeably with a decreasing test temperature. However, the peak load of the SAC305 specimen remained virtually unchanged with a reduction in the temperature. The Sn37Pb solder joints failed in an M3 failure mode under all the considered testing temperatures. The SAC305 solder joints displayed both M1 and M2 failure modes at R.T.; however, they failed almost exclusively in M1 mode at the lowest test temperature of −40°C.Originality/valueThis paper presents a novel technique for evaluating high‐speed impact strength and energy absorbance of Sn‐based and Pb‐free solders at the chip level within a low temperature control system. To overcome the drawbacks experienced in other studies, this study focused specifically on cryo‐impact testing systems and the performed experimental steps to improve the accuracy of post‐test analysis.

Analysis of dart impact resistance of low-density polyethylene and linear low-density polyethylene blown films via an improved instrumented impact test method

An improved instrumented impact test method is used to correlate the impact resistance of low-density polyethylene and linear low-density polyethylene blown films to their solid-state deformation process during impact test. The two materials, low-density polyethylene and linear low-density polyethylene, showed different deformation behaviors under the same impact testing conditions. The region before the peak force in the load versus deformation plot for low-density polyethylene was linear, whereas for linear low-density polyethylene two different slopes were observed. The average peak force values of linear low-density polyethylene film is about 14% greater than that of low-density polyethylene film. Furthermore, the measured deflection at the peak force is about 50% higher in the case of linear low-density polyethylene film. In addition, the energy to peak force of linear low-density polyethylene is more than twice higher than that of low-density polyethylene. In the region after the peak point, the low-density polyethylene exhibited another peak before failing and no such peak was observed for linear low-density polyethylene. Tensile test results with low strain rate of deformation have also been compared. The tensile stress–strain in machine direction (MD) and transverse direction (TD) direction play an important role during the biaxial deformation during the impact test. The crystallographic deformations were explained using the scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) techniques for lamellar structure and orientation. The low-density polyethylene film has developed columnar clusters of lamellae, which are aligned parallel to the TD direction. On the other hand, the linear low-density polyethylene film structure shows more randomly orientated and thicker lamellae than that of the low-density polyethylene film. The result of this structure is a more balanced toughness in both MD and TD directions.

Recycling of automotive lighting — effect of UV cured coating contaminants on polycarbonate toughness

Summary — This work presents studies on the impact of the coating on reprocessed polycarbonate (PC) in order to evaluate changes in the fracture behavior and toughness of polycarbonate. The comparison of instrumented and non-instrumented impact testing methods is given. The fracture mechanics parameters such as dynamic strain energy release rate (GId), and fracture toughness (K Id ) where determined. The coating creates non-homogeneously dispersed particles, which act as stress concentrators facilitating multiple crazing and causing embrittlement of the material. The fracture toughness was diminished only slightly and was accompanied with the rise of dynamic yield stress (d) and dynamic flexural modulus (Ed). The heat deflection temperature (HDT), melt volume flow rate (MVR) and density were affected only marginally in comparison to recycled polycarbonate without coating contaminants.

Use of a head component tester to evaluate the injury potential of an aircraft head-up display

Title 14 of the Code of Federal Regulations Part 25, §25.785 requires that seats and adjacent parts of the airplane be designed so that occupants will not suffer serious injury during an emergency landing as a result of expected inertial forces. The Federal Aviation Administration (FAA) guidance material cites several component impact test methods for use in determining whether an item or surface is potentially injurious. A head component tester (HCT) developed at the National Institute for Aviation Research of the Wichita State University was selected to assess the injury potential of a new cockpit-installed head-up display (HUD)'s combiner glass. A test procedure complying with the intent of the FAA guidance material was developed and validated by the Civil Aerospace Medical Institute (CAMI), Oklahoma City, OK. Subsequently, a computer model of the HCT impact into the HUD was developed by The Engineering Institute, Farmington, AR, and was correlated with CAMI test data. This model is useful for evaluating the effect of design parameters on HUD injury potential.

Dynamic Response on Free-Free Beam in Driving Point and Transfer Mobility Measurement under Bending Load

This paper aims to present the experimental result obtained from dynamic response on free-free beam in driving point and transfer mobility analysis using impact test method using hammer tips that are steel, plastic and rubber. The 8630C accelerometer and analyzer is used for data logging and for the analysis, the plastic hammer tip is chosen. The analytical and the experimental value then are compared for the free-free beam natural frequency, damping ratio, and stiffness value. As a result, the highest percentage error for natural frequency is approximated to 2.7%, the damping ratio is approximated to 3.115 × 10-3 and the stiffness value gives the major different between the experiment value and theoretical value. Finally, this method can be used to determine the properties of a structure such as natural frequency, mode shapes, damping ration and stiffness, respectively.

Exploring ‘nano filler’ based on oil palm ash in polypropylene composites

This study presents the utilization of oil palm ash (OPA), a siliceous material from the fiber of oil palm biomass, as a nanofiller for the development of polymer nanocomposites. Polypropylene-based polymer nano-composites reinforced with OPA along with a compatibilizer were prepared by a melt-mixing technique, using a double screw extruder. Variations in the mechanical, morphological, and thermal properties with the filler and compatibilizer loading were studied. The best dispersion occurred in the polymer nano-composites for which the interactions between the polymer matrix and nanosized OPA appeared to be the highest. The particle size and the dispersion of the oil palm ash within the matrix were determined by transmission electron microscopy. The as-synthesized composite materials were typically characterized by tensile and impact test methods. The morphology of the composite materials was studied by scanning electron microscopy. The thermal properties determined by thermogravimetric analysis (TGA) showed enhanced thermal stability of a series of composite materials. Also, melting studies were carried out by differential scanning calorimetry.

Engineering Properties of Epoxy Polymer Cement Concrete Reinforced with Glass Fibers

Previous research on mechanical properties and fracture behavior of concrete reinforced with glass fibers and some results are presented. It is well known that high strength concrete displays a brittle behavior and less tough characteristics than normal strength concrete. This type of behavior can be enhanced by incorporating various types of fibers or various types of matrix which lead to better mechanical properties and fracture properties. In this study, an experimental study on epoxy polymer cement concrete reinforced with glass fibers and steel fibers both used at a relatively low volume fraction is presented. Polymer concrete is a composite material formed by polymerizing a monomer and aggregate mixture. The polymerized monomer acts as the aggregates binder. In this research, the polymer is epoxy resin mixed with cement and aggregates as used in the foundry industry. Initiators and promoters are added to the resin prior to its mixing with the inorganic aggregates to initiate the curing reaction. Compressive, splitting, three-point bending and impact test methods have been used to characterize reinforced concrete materials and the results are analyzed statistically. Fracture behavior of steel fibers and glass fibers reinforced epoxy polymer cement concrete is investigated. This is a direct method to calculate two size independent fracture parameters, i.e., the critical stress intensity factor, KIC and the Crack Tip Opening Displacement (CTOD). Beams with central notch, fewer than three points bending using attached clip gauge to measure the CTOD are tested. The glass fibers were also pre-treated with silane to improve the adhesion between fibers and resin and fracture properties

Evaluation of the Fatigue Behavior of Aluminide Coating Steel Substrate Compounds by Means of the Impact Testing Method

The impact testing is an efficient experimental method that enables the quantitative and qualitative evaluation of the fatigue resistance of mono- and multilayer coatings deposited on various substrates, which was not possible with the common testing methods previously available. In this article the experimental assessment of the fatigue resistance of aluminide slurry coatings working under cyclic loading conditions by means of the dynamic impact testing method is presented. The fatigue failure mode, such cohesive or adhesive, of the investigated coatings is determined using scanning electron and optical microscopy, as well as Energy Dispersive X-ray (EDX) analysis. Critical values of impact load responsible for distinctive fatigue failure modes of the coating substrate system are obtained.

Experimental determination of the buckling load of rectangular plates using vibration correlation technique

This study investigates the use of a vibration correlation technique (VCT) to identify the buckling load of a rectangular thin plate. It is proposed that the buckling load can be determined experimentally using the natural frequencies of plates under tensile loading. A set of rectangular plates was tested for natural frequencies using an impact test method. Aluminum and stainless steel specimens with CCCC, CCCF and CFCF boundary conditions were included in the experiment. The measured buckling load was determined from the plot of the square of a measured natural frequency versus an in-plane load. The buckling loads from the measured vibration data match the numerical solutions very well. For specimens with well-defined boundary conditions, the average percentage difference between buckling loads from VCT and numerical solutions is -0.18% with a standard deviation of 5.05%. The proposed technique using vibration data in the tensile loading region has proven to be an accurate and reliable method which might be used to identify the buckling load of plates. Unlike other static methods, this correlation approach does not require drawing lines in the pre-buckling and post-buckling regions; thus, bias in data interpretation is avoided.

Viral Gastroenteritis: Pathogenesis and Laboratory Detection and Characterization in the Commonwealth of Virginia

Public health laboratories perform testing to identify and characterize cases and clusters of acute gastroenteritis (AGE). Viral pathogens, in particular norovirus, are reportedly the most common cause of AGE outbreaks. CaliciNet, a centralized database at the Centers for Disease Control and Prevention, collects and compares viral sequences for surveillance and outbreak tracking purposes. At the state level, viral agent testing supports epidemiologic investigations of AGE outbreaks. The resulting data are used to educate the public health and medical communities and to track mutations that may impact testing methods. A retrospective analysis of norovirus data generated by the Virginia State Laboratory between 2001 and 2009 assessed statewide trends compared to national data. The data demonstrate that Norovirus genogroup II outbreaks are the most prevalent cause of AGE outbreaks and that outbreaks exhibit a higher occurrence in the winter months and in adult care facilities in Virginia and nationally.

선박 장비 받침대의 동강성 평가를 위한 유한요소 모델링과 해석 인자에 관한 연구

This paper studies the finite element modeling and analytical parameters for the numerical evaluation of dynamic stiffness of large foundation for shipboard equipments such as marine diesel engine. For the purpose, numerical method and procedure to evaluate the dynamic stiffness are established based on the impact test method, which are applied for the dynamic stiffness evaluation of a real diesel generator foundation of ship. Numerical investigations compared with the measured data are carried out to evaluate the effects of modeling ranges of ship substructure, finite element sizes, lower support structures and damping coefficients. From the results, modeling and analytical parameters for proper evaluation of dynamic stiffness of large foundation of shipboard equipment are suggested.

A novel impact test system for more efficient reliability testing

Portable electronic products such as mobile phones experience various loadings in their use environments but accidental drops are encountered most frequently. Over the past few years the drop reliability of electronic assemblies has been studied by means of the travelling table test apparatuses described in the JESD22-B111 drop test standard. There are, however, a few essential shortcomings related to this approach: for example, (1) testing can be time-consuming as a result of the low impact repetition frequency (0.1 Hz) characteristic of the approach; (2) the peak deceleration amplitude varies from one pulse to another; (3) packages placed at different locations on the printed wiring board experience highly dissimilar loading conditions, and (4) the lifetime of a particular location varies significantly from one board to another. In order to overcome these shortcomings an alternative impact test method is presented in this paper. The new method is based on the use of a pneumatic cylinder to produce the desired shock pulses, for example those defined in the JESD22-B110A and JESD22-B111 standards. The measurements showed that the pneumatic test system is capable of producing peak deceleration well above the maximum (2900 G) stated in the JESD22-B110A. More importantly, a testing time an order of magnitude shorter was achieved by increasing the drop impact repetition frequency; an impact repetition frequency of 1.6 Hz was achieved with the pneumatic shock impact tester. Two improved component board attachments based on the support of the full board width were designed in order to simplify the bending motion of component boards. Both the finite element calculations and the experimental results showed that under the full board width support conditions the bending of the component board is more uniform and different component locations experience more equal strains as compared to bending under the conventional 4-point support conditions. The reliability tests that were performed verified that the full board width support produces the same failure modes and that the lifetimes of packages at different locations on the printed wiring board are more comparable with each other with the full board width support than they are with the conventional 4-point support. The benefits of the pneumatic tester that was developed are related to the time needed for testing, the stability of the impact pulse over long periods of time, and the more consistent lifetime statistics achieved by the simplified bending of the component board during testing.

S-3 自動車の衝突試験について(SYP:これから始める交通傷害研究)

S-3 自動車の衝突試験について(SYP:これから始める交通傷害研究)

네트공법 슬라브의 소음 및 진동 해석

The slab(flat) truss plate used for building construction is analyzed for vibration and noise. Using floor impact test and numerical method (FEM), both net form and traditional form are compared for vibration and noise. The results show that the frequencies of a net form are lower than those of a traditional form in the case of free vibration, and the noise values of a net form are lower than those of a traditional form for the range from 500 ㎐ to 2000 ㎐.

Fracture Toughness Evaluation of Laser Beam-Welded Joints of 780 MPa-Strength Class Steel

For fracture assessment of steel structures with laser beam-welded joints, it is significantly important to evaluate the fracture toughness of the weld metal. However, the fracture toughness of weld metal is often impossible to measure by standard Charpy impact testing in the brittle-to-ductile transition or upper-shelf temperature region, because of fracture path deviation (FPD) from the weld metal due to narrow weld bead and a high degree of overmatching in strength. In this work, evaluated fracture toughness of laser beam-welded joints of 780 MPa-strength class (HT780) steel is examined by Charpy impact testing and CTOD fracture toughness testing. The improved Charpy impact tests, using the specimen with three parallel welds or the side-groove specimen, are conducted in order to prevent FPD. The applicability and significance of the improved impact test methods to the laser beam-welded joints of high-strength steel are investigated by means of Weibull stress analysis. The Weibull stress analysis indicates that the 3-weld method could not necessarily prevent FPD in laser beam-welded joints of HT780 steel, since side beads are not as hard as main weld beads, due to reheating at the main weld. On the other hand, a side-groove specimen is effective for avoiding FPD, but intrinsic VE of the weld metal could not necessarily be obtained by using this specimen.

Comparing drop impact test method using strain gauge measurements

In this paper, strain gauges are used to measure the dynamic response during drop impact. A set of high-speed data acquisition system is used to capture the real-time strain response of critical locations. Finite Element Modelling is used to determine where to place the strain gauges. Two board level drop impact test methods, A and B, are compared by the strain gauge measurements. Results show significant differences in strain amplitude, strain rate, frequency, rebound, and damping. Method B produces higher strain amplitude, stronger rebound, and less damping, while method A produces higher frequency and strain rate. Damping and rebound are important factors for both test methods. The differences of two test methods are due to the contributions from test condition and test board. Combination test were conducted to investigate the contribution of test condition and test board. Results show that test board dominates strain amplitude, frequency, mode and damping, while test condition shows influence on strain amplitude and rebound. Test condition A produces higher strain amplitude, while test condition B produces stronger rebound. Test board A produces higher frequency, while test board B produces higher strain amplitude and less damping. Test board contributes more to the strain amplitude than test condition. Strain rate is dependent on both the test condition and test board.

Instrumented tensile–impact test method for shape memory alloy wires

New instrumented tensile–impact test method is proposed for the characterization of shape memory alloy wires in the strain-rate range from 1 to 10 2 s −1. The force and the velocity evolution during the impact are registered and, based on these curves, the stress–strain response at impact may be obtained. This method is able to measure strain-rate dependent parameters, such as the direct and reverse stress-induced martensitic transformation stresses or the dissipated energy. Moreover, the accuracy of properties measured with this method, such as the Young's modulus of the austenitic phase or the permanent strain after load–unload deformation, is higher than those calculated exclusively from the integration of the force–time curves.