Impact Test Method Research Articles

Evaluation and analysis method of aviation seat crashworthiness

In order to research the structural response characteristics of an aviation seat under crash scenarios,an evaluation and analytical method of aviation seat crashworthiness was proposed for a seat / occupant system. A finite element model of the seat was established based on actual seat geometry and reasonable simplifying assumptions,then the seat model was coupled with a 50 th Hybrid Ⅲ multi-rigid-body dummy model.A crashworthiness simulation of this seat / occupant system was carried out according to airworthiness regulations which define dynamic impact test methods and qualification requirements for crew seats in general aviation aircraft in consideration of the cabin floor deformation. Seat deformations and energy-absorption,as well as occupant injury indicators under typical loading conditions were obtained. The results show that the seat /occupant system suffers more serious damage under forward and lateral loading,and the plastic deformation of the front seat beams increases when the backrest adjustment mechanism is too rigid. Cabin floor deformation aggravates seat structure damage. Compared with pitch deformation,roll deformation of the cabin floor causes greater damage. Modifications for the seat structure are proposed to improve its crashworthiness.

高温環境における衝突試験方法

高温環境における衝突試験方法

IMPACT RESISTANCE OF STEEL FIBER REINFORCED CONCRETE

Synopsis/ ABSTRACT The present experimental investigation is to study the impact resistance of Fiber Reinforced Concrete with inclusion of steel fibers. The concrete composites comprises of steel fibers in different percentages. The hooked end type steel fibers varied from 0 to 2.5% at an interval of 0.5% by weight of cement. A simple economical and practical drop weight impact testing machine was used to determine the impact resistance for Steel Fiber Reinforced concrete [SFRC]. Impact test were carried out on SFRC with aspect ratio (l/d) as 60. The specimens were tested at 7 days and 28 days strength for concrete grade category like M20, M30 and M40. The specimens for impact studies were tested by drop weight Impact test method which was recommended by ACI-544 committee. The addition of steel fibers to concrete has improved the impact resistance considerably. The test results showed the variation of impact energy strength with different volume fraction of fibers.

A Novel Method for Impact Testing of Small Specimens - Numerical Simulation and Experiments

A novel method for dynamic testing of small specimens, based on impact loading, is proposed. This is motivated by the desire to elicit the dynamic mechanical response of single solder joints measuring 0.5 mm smaller in size. Impact loading is generated through impact of a tubular striker against a loading plate which is initially in contact with the specimen. The mechanical response of the specimen is derived from noting the stress waves generated in slender bars attached to the loading plate and specimen. Through this approach, dynamic tension or compression can be conveniently applied using the same test apparatus, and exact alignment of the slender bars attached is not critical. In addition, wave dispersion or attenuation in the bars (e.g., when polymer bars are used) has much less influence on the accuracy of results obtained. The equations governing this novel approach are derived and validated by finite element modeling. A prototype of a miniature impact tester was consequently fabricated, and tests on small aluminum specimens showed results comparable to that employing traditional split Hopkinson bar systems. The test arrangement was utilized for dynamic testing of lead-free single solder joint specimens, and initial results obtained are presented.

サッカー用スポーツソックスの衝撃ずり落ち試験法

サッカー用スポーツソックスの衝撃ずり落ち試験法

Mobile Impact Testing for Structural Flexibility Identification with only a Single Reference

AbstractIn contrast to the traditional impact test method requiring a number of sensors to measure the entire structure, a mobile impact test method sequentially measuring segments of the structure and the related data processing strategy is proposed. Especially, only a single reference node is required when integrating measurements of the segments to identify the flexibility characteristic of the entire structure. Equations are first derived to adjust the magnitudes of mode shapes of the substructure to a same scaling level. Then the phase angle concept is utilized to determine the coherent signs of mode shapes for structural flexibility identification. The advantage of the proposed method is that it outputs the same flexibility identification results as the traditional impact test method, whereas it only requires a single reference no matter how many segments of the structure are divided, thus it significantly speeds up the impact test and makes it be an ideal approach for rapid testing of short/middle span bridges. Numerical and experiment examples investigated successfully verify the effectiveness of the proposed method for structural flexibility identification.

Structural Identification by Processing Dynamic Macro Strain Measurements

In contrast to traditional modal identification methods processing structural accelerations for modal parameter identification, a multiple reference impact testing method using long-gauge fiber optical sensors and the related data processing approach are proposed. First, macro strains of key structural elements during the impact testing are measured through long-gauge fiber optic sensors, which subsequently are used to estimate the strain frequency response functions (FRFs) of the structure. Second, an approach is proposed to estimate strain mode shapes from the strain FRFs, and corresponding displacement mode shapes are calculated by applying an improved conjugate beam method. Finally, the strain flexibility character of the structure is identified by using the identified strain and displacement mode shapes with normalization. The advantage of long-gauge fiber optic sensors measuring averaged strains in a long length (e.g., 1 meter) provides the opportunity for strain modal analysis. The output of the proposed method, strain flexibility, is meaningful for static strain prediction and structural capacity evaluation. Examples investigated successfully verified the effectiveness of the proposed method for structural strain flexibility identification.

The Effect of Intermetallic Phases on Ductile to Brittle Transition of Aluminium-Iron Alloy

The effect of intermetallic phases and grain size on ductile to brittle transition temperature of Aluminium-Iron alloy (Al–11% Fe) was investigated in this research work. An Izod impact testing method was adopted to study the DBTT in the temperature interval of 77 K to 373 K. The ductile-brittle transition points: fracture transition plastic (FTP), fracture-appearance transition temperature (FATT), impact energy transition temperature (IETT), fractional surface area of cleavage (brittle) and fibrous (ductile) fractures and grain size of the samples were also determined. The fracture toughness of Al-Fe alloy found decreasing with temperature in contrast to conventional materials. The fractographic investigation revealed that the microstructural changes play a major role in determining the fracture toughness of these alloys. Annealing of these samples slightly improved the fracture toughness as the spherical morphology of intermetallic particles resists the crack propagation.

Impact Toughness of 0.3 Mass% Carbon Tempered Martensitic Steels Evaluated by Instrumented Charpy Test

The effect of tempering temperature on the impact toughness of 0.3 mass% carbon martensitic steels with prior austenite grain (PAG) size of about 6 μm and 30 μm were investigated. Instrumented Charpy impact test (ICIT) method was used to evaluate the impact toughness. The tempering temperature of 723K gives the largest difference in the Charpy impact energy at room temperature (RT) between the specimens with two different PAG sizes. Investigation of the test temperature dependence of Charpy impact energy in the 723K tempered steels shows a steep transition at around 200 K for the 6 μm PAG specimen, while it shows a continuous slow transition in a wide range of temperature for the 60 μm PAG specimen. ICIT waveform analysis shows that the fracture propagation energy in stead of the fracture initiation energy mainly controls the temperature dependence of the impact energy. The carbide size distribution in these two specimens was investigated by SEM and TEM. The 60 μm PAG specimen shows the distribution of coarser carbides than does the 6 μm PAG specimen, which seems to be the main reason for the observed difference between them in the Charpy impact energy and the other properties of impact fracture.

Fracture toughness of filament wound BFR and GFR arc shaped specimens with Charpy impact test method

The aim of this study is an examination of Charpy impact behaviors of ±6 layered basalt (BFR) and glass fiber reinforced (GFR) epoxy composite pipe at the degree of ±55° filament winding angle with the arc-shaped specimen technique of different notch depth ratios (a/W). As a result of Charpy impact experiments, BFR composites were determined to have higher impact energy level and impact fracture toughness than GFR composites. The occurred average delamination areas in between layers were detected by an image processing method during the impact process. The delamination damage in GFR composites was observed to be more dominant damage than in BFR composites. It is understood that damage modes change when the notch depth ratio increases for composites. In BFR composites, the predominant damage mode was determined to be fiber breakage as a consequence of experiments and SEM analyses.

Mechanical Behavior and Fracture Toughness Evaluation of Multiphase Polymer Nanocomposites Using Impact and J-Integral via Locus Method

Fracture behaviors of fibrillar silicate clay (MMT) filled thermoplastic polyolefin (TPO) containing polypropylene (PP) blended with ethylene-propylene-diene monomer (EPDM) were systematically investigated using impact test method and J-integral by locus method. Drastic increase in impact strength is observed for all developed compositions and generally shows higher value for the selected phases containing dispersed nanoclay in PP matrix. A fracture mechanics approach has been adopted by mode I test, and the effects of specimen geometry have been investigated. Increase in interlaminar fracture energy value, Gc, and J-integral value, Jc, is marked as the crack propagated through the composite; that is, a rising “R-curve” is observed. Toughness measurements revealed that the fracture toughness increased with increasing clay content reaching maximum at 3 wt% of clay than pure PP. Moreover, enhancement of fracture toughness was more remarkable than that of stiffness. The fracture surfaces taken from different specimens were observed for exploring the fracture mechanisms using transmission electron microscopy (TEM) revealed a strong particle-matrix adhesion.

철도차량 전면창유리 충격시험에 관한 연구

철도차량 전면창유리 충격 시험 및 특성 파악을 위해 유럽 및 국내의 전면창유리 충격 시험 방법을 비교 검토하였다. EN 15152에 따른 고속철도차량의 전면창유리 충격 시험이 가능한 정도인 약 500km/h 속도로 충돌체를 발사할 수 있는 압축 공기식 충격 실험 발사 장치를 설계 및 제작하였으며, 이 발사장치의 충돌체 발사 성능 확인을 위해 속도 보정 실험을 실시하여 압축 공기에 따른 충돌체의 발사 속도 관계식을 도출하였다. 도시철도 및 일반철도에 사용되는 동일한 사양의 전면창유리 시편(<TEX>$1000mm{\times}700mm$</TEX>)에 제작한 발사 장치를 이용해 충돌 시험을 수행하여 충돌 속도에 따른 시편의 충격 특성을 살펴보았다. This study describes impact test methods for a rolling-stock windscreen executed in Korea and Europe. Air-pressurized impact test equipment for the front windscreens of high speed trains was designed and manufactured. The equipment is capable of launching a projectile at 500km/h, in accordance with EN 15152's impact test method. Calibration of the test equipment was conducted to find an equation relating air pressure and projectile velocity. Specimens (<TEX>$1000mm{\times}700mm$</TEX>) having similar specifications with the front windscreens in metro and conventional trains were used to conduct impact tests with this equipment to research the impact characteristics of the screens according to the impact velocity.

Impact Test Method for Automobile Plastic Tank Research and Equipment Development

The automobile fuel tank is an important component of the car, and it played an important role in the safety. Its one of the parts of car must be test in china and another place such as Europe before this parts used in a new car. In this article, the difference of requirement of low-temperature impact resistance is compared in GB18296-2001 and 70/221/EEC or ECE R34, then discuss the simple structure of pendulum for impact test according to GB18296-2001 and find it is not suitable for the impact test which required in 70/221/EEC.After that, designed an impact test rig meeting the requirements of the standard of GB18296-2001 and regulations of 70/221/EEC.The impact test bench is easy to operate, efficiency and safety.

Effects of Flexible Functional Layer Incorporated with Rubber Powder on the Vibration Reduction of Cement Concrete Pavement

Small sized specimen of cement concrete pavement structure was prepared indoors. By utilizing the dynamic signal tester and obtaining the vibration frequency domain signals through the falling-ball vibration impact test method, the attenuation rules of the vibration response of the pavement structure were analyzed and the effects of the flexible functional layer on the vibration-reduction and energy-absorption were studied. The results showed that, after compared with the normal flexible functional layer, the flexible functional layer incorporated with rubber powder resulted in the pavement structure having the better capacities of vibration-reduction energy-absorption and impact resistance. Accordingly, the rupture failure of the cement concrete pavement induced by vehicle load can be reduced.

High-speed impact test using an inertial mass and an optical interferometer

A high-speed impact testing method for evaluating mechanical properties of materials is proposed using an inertial mass and a dual beat-frequencies laser Doppler interferometer (DB-LDI). In this method, an inertial mass levitated using an aerostatic linear bearing is made to collide with the material being tested at a high initial velocity. During the collision, the velocity of the mass, which is even higher than the critical velocity (±0.56 m/s) defined by the frequency difference of the Zeeman laser, is accurately measured using the DB-LDI. The position, acceleration, and impact force of the mass are calculated from the measured velocity. Using the proposed method, the mechanical properties of a visco-elastic material under a high-speed impact loading condition can be accurately evaluated.

Implementation of One Kind of Side Impact Method for Child Restraint System Based on Sled Test

Although accident analysis shows that side impact accidents continue to be dangerous for children in cars, the majority technical regulations of Child Restraint Systems (CRS) are focused on the crash performance under the frontal and rear impacts and do not include a side impact test, the main reason is that no good method to test side impact performance of CRS has been agreed on yet in the world. In this paper one side impact test method based on double sled concept is presented and realized. And several CRS models are tested; injury response values are measured from child dummy. It is observed that the sled buck concept is repeatable and able to distinguish preliminarily between CRS models.

Ball Impact Reliability of Zn-Sn High-Temperature Solder Joints Bonded with Different Substrates

In this study, the high-speed deformation behavior of solder joints formed with Pb-free Zn-Sn and commercial Pb-Sn alloys bonded on different substrates was investigated by the ball impact test method. Overall, Zn-Sn joints exhibited greater impact strength but inferior impact toughness than Pb-Sn joints. This can be ascribed to the high hardness of Zn-Sn solders resulting in partial or overall interfacial fracture. In contrast, the joints with soft Pb-Sn solders all showed a ductile fracture feature. It is suggested that, for the joints revealing brittle fracture, the impact toughness (impact energy) increased with the plastic ability of interfacial intermetallic compounds, while for those showing a ductile fracture mode, the impact energy deteriorated with a hardened solder matrix resulting from substrate dissolution.

충격공진시험을 이용한 다양한 공극률을 가진 투수성 아스팔트 혼합물의 동탄성계수 변화 측정에 관한 연구

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

Experimental evaluations of material damping in timber beams of structural dimensions

Understanding the inherent damping mechanisms of floor vibrations has become a matter of increasing importance following the development of new composite floor layouts and increased span. The present study focuses on the evaluation of material damping in timber beam specimens with dimensions that are typical of common timber floor structures. Using the impact test method, 11 solid wood beams and 11 glulam beams made out of Norway Spruce (Picea abies) were subjected to flexural vibrations. The tests involved different spans and orientations. A total of 420 material damping evaluations were performed, and the results are presented as mean values for each configuration along with important statistical indicators to quantify their reliability. The consistency of the experimental method was validated with respect to repeatability and reproducibility. General trends found an increasing damping ratio for higher modes, shorter spans, and edgewise orientations. It is concluded from the results that material damping of timber beams of structural dimensions is governed by shear deformation, which can be expressed more conveniently with respect to the specific mode shape and its derivatives.

Influence of the percentage of recycled material on the mechanical properties of low-density polyethylene, polyethylene terephthalate, and polyvinyl chloride

The aim of this article was to fabricate virgin polyvinyl chloride, polyethylene terephthalate, and low-density polyethylene blended with their corresponding recycled material in different ratios of virgin/recycled via injection molding and to evaluate their tensile strength, impact fracture, and hardness behavior. Raman spectroscopy was used to qualitatively study the characteristics of the recycled material in comparison with the virgin material. The impact testing method was the Charpy impact test, and for the hardness measurement, the shore D hardness method was used. The tensile tests were performed following the ATSM 683 standard. Scanning electron microscopy was used for chemical analysis and imaging to confirm the presence of contaminants.