• Title/Summary/Keyword: drop weight test

Search Result 154, Processing Time 0.022 seconds

VHCF Characteristics of SCMH2 Steel Depending on the Surface Treatment Conditions (SCMH2 고속회전축재의 표면처리조건에 따른 VHCF 피로특성에 관한 연구)

  • Suh, C.M.;Suh, C.H.;Suh, M.S.
    • Journal of Welding and Joining
    • /
    • v.31 no.4
    • /
    • pp.47-53
    • /
    • 2013
  • SCMH2 steel is widely used in the industrial members of car and tractor. This study focused on material properties and evaluation technology of the SCMH2 steel regarding the surface treatment followed by carburizing and nitriding, by means of impact test, hardness test. and fatigue test including HCF (high cycle fatigue) and VHCF (very high cycle fatigue). Drop weight impact tester (Instron, 9250 Hv) and Cantilever type rotating-bending fatigue tester (YRB200, 3150 rpm) were used to characterize the SCMH2 standard specimen before and after carburizing/nitriding. In order to understand those effects on fatigue characteristics and material properties, the fractured surfaces were carefully observed and analyzed by SEM (scanning electron microscope) and EDS (energy-dispersive X-ray spectroscopy).

Experimental investigation of impact behaviour of shear deficient RC beam to column connection

  • Murat, Aras;Tolga, Yilmaz;Ozlem, Caliskan;Ozgur, Anil;R. Tugrul, Erdem;Turgut, Kaya
    • Structural Engineering and Mechanics
    • /
    • v.84 no.5
    • /
    • pp.619-632
    • /
    • 2022
  • Reinforced concrete (RC) structures may be subjected to sudden dynamic impact loads such as explosions occurring for different reasons, the collision of masses driven by rockfall, flood, landslide, and avalanche effect structural members, the crash of vehicles to the highway and seaway structures. Many analytical, numerical, and experimental studies focused on the behavior of RC structural elements such as columns, beams, and slabs under sudden dynamic impact loads. However, there is no comprehensive study on the behavior of the RC column-beam connections under the effect of sudden dynamic impact loads. For this purpose, an experimental study was performed to investigate the behavior of RC column-beam connections under the effect of low-velocity impact loads. Sixteen RC beam-column connections with a scale of 1/3 were manufactured and tested under impact load using the drop-weight test setup. The concrete compressive strength, shear reinforcement spacing in the beam, and input impact energy applied to test specimens were taken as experimental variables. The time histories of impact load acting on test specimens, accelerations, and displacements measured from the test specimens were recorded in experiments. Besides, shear and bending crack widths were measured. The effect of experimental variables on the impact behavior of RC beam-column connections has been determined and interpreted in detail. Besides, a finite element model has been established for verification and comparison of the experimental results by using ABAQUS software. It has been demonstrated that concrete strength, shear reinforcement ratio, and impact energy significantly affect the impact behavior of RC column-beam connections.

Numerical and Experimental Investigation on Impact Performance of Fiber Metal Laminates Based on Thermoplastic Composites (열가소성 복합재료를 기반한 섬유금속적층판의 충격 거동에 관한 실험 및 수치적 연구)

  • Lee, Byoung-Eon;Kang, Dong-Sik;Park, Eu-Tteum;Kim, Jeong;Kang, Beom-Soo;Song, Woo-Jin
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.24 no.5
    • /
    • pp.566-574
    • /
    • 2016
  • Fiber metal laminates, which are hybrid materials consisting of metal sheets and composite layers, have contributed to aerospace and automotive industries due to their reduced weight and improved damage tolerance characteristics. In this study, the impact performance of the laminates, which are comprised of a self-reinforced polypropylene and two aluminum sheets, and the pure aluminum alloy sheet material were investigated experimentally via numerical simulation. In order to compare the impact performance, the laminates and aluminum alloy were examined by assessing the impact force, energy time histories, and specific energy absorption. ABAQUS is a commercial software that is used to simulate the actual drop-weight tests. Based on this study, it is noted that the impact performance of the laminates was superior to that of the aluminum alloy. In addition, a good agreement between the experimental and numerical results can be achieved when the impact force and energy time histories from the experiments and the numerical simulations are compared.

Effect of excitation type on dynamic system parameters of a reinforced concrete bridge

  • Wahab, M.M. Abdel;De Roeck, G.
    • Structural Engineering and Mechanics
    • /
    • v.7 no.4
    • /
    • pp.387-400
    • /
    • 1999
  • Damage detection in civil engineering structures using the change in dynamic system parameters has gained a lot of scientific interest during the last decade. By repeating a dynamic test on a structure after a certain time of use, the change in modal parameters can be used to quantify and qualify damages. To be able to use the modal parameters confidentially for damage evaluation, the effect of other parameters such as excitation type, ambient conditions,... should be considered. In this paper, the influence of excitation type on the dynamic system parameters of a highway prestressed concrete bridge is investigated. The bridge, B13, lies between the villages Vilvoorde and Melsbroek and crosses the highway E19 between Brussels and Antwerpen in Belgium. A drop weight and ambient vibration are used to excite the bridge and the response at selected points is recorded. A finite element model is constructed to support and verify the dynamic measurements. It is found that the difference between the natural frequencies measured using impact weight and ambient vibration is in general less than 1%.

A Study on Low-Velocity Impact Characterization of Sandwich Panels with Metal and Laminate Composite Facesheets (금속재와 적층복합재 면재를 갖는 샌드위치 패널의 저속충격 특성 연구)

  • Lee, Jae-Youl;Lee, Sang-Jin;Jo, Se-Hyun;Mok, Jai-Kyun;Shin, Kwang-Bok
    • Proceedings of the KSR Conference
    • /
    • 2007.05a
    • /
    • pp.144-150
    • /
    • 2007
  • In this paper, the low velocity response of four different sandwich panels with metal and laminate composite facesheets has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Square samples of 100mm sides were subjected low-velocity impact loading using an instrumented testing machine at six energy levels. Impact parameters like maximum force, time to maximum force, deflection at maximum force and absorbed energy were evaluated and compared for four different types of sandwich panels. The impact test results show that sandwich panel with composite laminate facesheet could not observe damage mode of a permanent visible indentation after impact and has a good impact damage resistance in comparison with sandwich panel with metal aluminum facesheet.

  • PDF

A Study of Dance Movement Training on the Wellness of young Women (율동적 동작 훈련이 젊은 여성의 Wellness에 미치는 영향)

  • ;Lou Heber
    • Journal of Korean Academy of Nursing
    • /
    • v.25 no.3
    • /
    • pp.538-548
    • /
    • 1995
  • Exercises are achievement oriented, the process is frequently perceived as hard and difficult Participants drop out from exercise programs in the middle of the training period. Dance movement, which is the deliberate and systematic use of movement, is enjoyable during the movement and provides opportunities for persons to express them-selves. Regular long term dance movement may in-duce a training effect with a decreased drop out rate. Dance movement could be one way to attain wellness, however, there have been few studies to evaluate both physiological and psychological aspects of dance movement. This study focused on evaluating the effects of dance movement training on body weight, resting blood pressure and heart rate, limb circumference and strength, stress response and subjective feelings. This quasi-experimental study was designed as a nonequivalent control group pre test -post test study. Ten healthy fe-male subjects, aged between 19 and 31 years volunteered for an eight week dance movement program. Ten healthy female subjects, between 19 and 21 years of age paticipated as controls. None of the subjects had performed regular physical activity for six months prior to the study. Dance movement was created with reference to Heber's movement guide. The Dance movement program consisted of approximately 30 minutes of dance, three days per week, for eight weeks. During each 30 minute work out, there were approximately 5 minutes of warm-up dancing, 20 minutes of conditioning dance and 5 minutes of cool-down dancing. The intensity for the conditioning phase was at between 60% and 65% of age-adjusted maximum heart rates. Body weight, resting blood pressure and heart rate, circumference of mid upper arm, mid thigh and mid calf, muscle strength of upper and lower limb, physical and psychological response to stress were measured prior to, and following the experimental treatment. Body weight was measured by digital weight scale(Kyung In Corp., Korea). Resting systolic and diastolic blood pressure were measured by sphygmomanometer, Resting heart rate was measured for one minute in a relaxed sitting position using the radial artery. Circumference of mid upper arm, mid thigh and mid calf was determined by tape measure. Muscle strength of the upper extremities was measured by a grip dynamometer (Takei Corp. No.1857, Japan) and that of the extremities was measured by the length of time the leg could be held at 45° Physical and psychological responses to stress were measured using the Symptoms of Stress (SOS)Scale. Paticipants in the dance movement were interviewed by the facilitator following the eight weeks, and their thematic responses about the dance movement were recorded. Following the eight week dance movement train-ing, body weight decreased significantly, circumference of mid thigh and mid calf increased. The length of time leg - raising could be held tended to increase following the dance movement training. Resting systolic and resting heart rate showed a tendency to decrease. Total mean score of stress response tended to de-crease, and mean score of habitual patterns, do-pression, anxiety / fear, anger and cognitive disorganization decreased remarkably following the eight week dance movement. Thematic responses about the dance movement were positive following the training.

  • PDF

A Study on the Impact Behavior of Bulletproof Materials According to the Combining Method

  • Jihyun Kwon;Euisang Yoo
    • Elastomers and Composites
    • /
    • v.57 no.4
    • /
    • pp.157-164
    • /
    • 2022
  • Representative bulletproof materials, such as aramid or ultra-high molecular weight polyethylene(UHMWPE), have excellent strength and modulus in the plane direction but are very vulnerable to forces applied in the thickness direction. This paper reports a study on the effects of reinforcement in the thickness direction when bulletproof composite fabrics are prepared to improve their performance. Aramid and UHMWPE fabrics were combined using the film-bonding, needle-punching, or stitching methods and then subjected to low-velocity projectile and ball-drop impact tests. The results of the low-velocity projectile test indicated that the backface signature(BFS) decreased by up to 29.2% in fabrics obtained via the film-bonding method. However, the weight of the film-bonded fabric increased by approximately 23% compared with that obtained by simple lamination, and the fabric stiffened on account of the binder. Flexibility, light weight for wearability, and excellent bulletproof performance are very important factors in the development of bulletproof materials. When the needle-punching method was used, the BFS increased as the fibers sustained damage by the needle. When the composite fabrics were combined by stitching, no significant difference in weight and thickness was observed, and the BFS showed similar results. When a diagonal stitching pattern was employed, the BFS decreased as the stitching density increased. By contrast, when a diamond stitching pattern was used, the fabric fibers were damaged and the BFS increased as the stitching density increased.

Estimation of fracture toughness of X65 and X70 steels by DWTT (X65 및 X70강 가스배관의 DWTT 및 파괴인성평가)

  • Cho, Ye-Won;Song, Young-Ho;Kim, Jeong-Min;Kim, Woo-Sik;Park, Joon-Sik
    • Journal of the Korean Institute of Gas
    • /
    • v.16 no.3
    • /
    • pp.54-64
    • /
    • 2012
  • DWTT (Drop Weigh Tearing Test) is one critical method that can exhibit the fracture properties of line pipe steel, since it estimates the properties with real pipe steel. In this study, the ductile portion, inverse fracture ratio and absorbed energy of API X65 and X70 line pipe steels were estimated with temperature variation. Both steels showed that the ratio of ductile area and absorbed energy were decreased with respect to decreasing the test temperature. However, while the ductile fracture behavior exhibited until $-40^{\circ}C$ for the X70 steel, but it showed until $-30^{\circ}C$ for the X65 steel. The fracture properties were discussed with respect to test temperatures.

Additional Effect of Zeolite Based on Bactericidal Activated Carbon Spheres with Enhanced Adsorption Effect and Higher Ignition Temperature

  • Zhu, Lei;Ye, Shu;Asghar, Ali;Bang, Seong-Ho;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
    • /
    • v.53 no.1
    • /
    • pp.68-74
    • /
    • 2016
  • In this study, the fabrication of zeolite combined activated carbon spherical samples was carried out as follows. Briefly, ZSM-5 zeolite and activated carbon were composed as main absorbent materials; by controlling the weight percentage of zeolite and binder materials, a series of spherical samples (AZP 4, 6, 8) were prepared. These spherical samples were characterized by BET, XRD, SEM, EDX, and pressure drop; benzene and iodine adsorption tests, bactericidal effect test, and ignition temperature test were also performed. The adsorption capability was found to depend on the BET surface area; the spherical samples AZP6 with high BET surface area of $1011m^2/g$ not only exhibited excellent removal effects for benzene (24.9%) and iodine (920mg/g) but also a good bactericidal effect. The enhanced ignition temperature may be attributed to the homogeneous dispersion conditions and the proper weight percentage ratio between zeolite and activated carbon.

Vibration performance characteristics of a long-span and light-weight concrete floor under human-induced loads

  • Cao, Liang;Liu, Jiepeng;Zhou, Xuhong;Chen, Y. Frank
    • Structural Engineering and Mechanics
    • /
    • v.65 no.3
    • /
    • pp.349-357
    • /
    • 2018
  • An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.