• Title, Summary, Keyword: Impact Energy

Search Result 2,733, Processing Time 0.058 seconds

Impact Energy Absorption Mechanism of Largely Deformable Composites with Different Reinforcing Structures

  • Kang, Tae-Jin;Kim, Cheol
    • Fibers and Polymers
    • /
    • v.1 no.1
    • /
    • pp.45-54
    • /
    • 2000
  • Impact behaviors of the large deformable composites of Kevlar fiber reinforced composites of different preform structures have been investigated. An analytic tool was developed to characterize the impact behavior of the Kevlar composites. The image analysis technique, and deply technique were employed to develop energy balance equation under impact loading. An energy method was employed to establish the impact energy absorption mechanism of Kevlar multiaxial warp knitted composites. The total impact energy was classified into four categories including delamination energy, membrane energy, bending energy and rebounding energy under low velocity impact. Membrane and bending energy were calculated from the image analysis of the deformed shape of impacted specimen and delamination energy was calculated using the deplying technique. Also, the impact behavior of Kevlar composites under high velocity impact of full penetration of the composite specimen was studied. The energy absorption mechanisms under high velocity impact were modelled and the absorbed energy was classified into global deformation energy, shear-out energy, deformation energy and fiber breakage energy. The total energy obtained from the model corresponded reasonably well with the experimental results.

  • PDF

Study on the Prediction of the Work-Energy to the Maximum Load and Impact Bending Energy from the Bending Properties (국산 소경재의 휨 성질을 이용한 충격에너지와 최대하중까지 일-에너지 예측연구)

  • Cha, Jae-Kyung
    • Journal of the Korea Furniture Society
    • /
    • v.19 no.5
    • /
    • pp.350-357
    • /
    • 2008
  • This research investigates the bending properties to predict the work-energy to maximum load and impact bending energy from static bending and impact bending test. Specimens were prepared from lumber made of thinning crop-trees. Matched specimens were used for MC 12% and green moisture specimens to measure the effect of moisture content on the absorbed energy from static and impact bending tests. The bending properties such as MOE, MOR, etc. is a good predictor to investigate the work-energy and work-energy per unit volume from static bending and impact bending test. The impact bending energy is increased with increasing moisture content. However, the work to maximum load from static bending test is increasing with increasing the MC only for higher density species.

  • PDF

Impact energy absorbing effect by the buckling of impact limiter's case of radioactive material transport cask (방사성물질 수송용기 충격완충제 케이스의 좌굴변형에 의한 충격흡수효과)

  • Ku, Jeong-Hoe;Seo, Gi-Seok;Min, Deok-Gi;Kim, Yeong-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.22 no.4
    • /
    • pp.826-833
    • /
    • 1998
  • The energy-absorbing characteristic of impact limiters affects the cask design so significantly that it should be evaluated as accurate as possible. The objective of this study is to find the influence of the impact limiter's steel case and gusset plates which enclose the shock absorbing cellular material on the impact energy absorption. The influence of impact limiter's steel case and gusset plate stiffeners on the impact energy absorption behavior under horizontal drop impact was evaluated for a radioactive isotope transport cask. Though the impact limiters mitigate the impact damage of the cask, the impact limiter's steel case and gusset plate stiffeners increase the impact force so significantly that should be designed as soft as possible. The impact analysis without considering impact limiter's steel case and gusset plates stiffener gives non-conservative results, so the stiffness of the steel case and gusset plates should be considered in impact analysis.

A Study on Low Velocity Impact Characteristics of DP 780 High Strength Steel Sheet with Thickness of 1.7 mm on the Free Boundary Condition Using Three-Dimensional Finite Element Analysis (3 차원 유한요소해석을 이용한 자유경계조건에서의 두께 1.7 mm DP780 고강도 강판의 저 속 충격 특성 분석)

  • Ahn, Dong-Gyu;Nam, Gyung-Heum;Seong, Dae-Yong;Yang, Dong-Yol;Lim, Ji-Ho
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.27 no.11
    • /
    • pp.46-56
    • /
    • 2010
  • The present research works investigated into the low velocity impact characteristics of DP 780 high strength steel sheet with 1.7 mm in thickness subjected to free boundary condition using three-dimensional finite element analysis. Finite element analysis was carried out via ABAQUS explicit code. Hyper-elastic model and the damping factor were introduced to improve an accuracy of the FE analysis. An appropriate FE model was obtained via the comparison of the results of the FE analyses and those of the impact tests. The influence of the impact energy and nose diameter of the impact head on the force-deflection curves, impact time, absorption characteristics of the impact energy, deformation behaviours, and stress-strain distributions was quantitatively examined using the results of FE analysis. The results of the FE analysis showed that the absorption rate of impact energy lies in the range of the 70.7-77.5 %. In addition, it was noted that the absorption rate of impact energy decreases when the impact energy increases and the nose diameter of the impact head decreases. The local deformation of the impacted region was rapidly increased when the impact energy was larger than 76.2 J and the nose diameter was 20 mm. A critical impact energy, which occur the instability of the DP780, was estimated using the relationship between the plastic strain and the impact energy. Finally, characteristics of the plastic energy dissipation and the strain energy density were discussed.

A STUDY ON IMPACT CHARACTERISTICS OF THE STACKING SEQUENCES IN CFRP COMPOSITES SUBJECTED TO FALLING-WEIGHT IMPACT LOADING

  • Im, K.H.;Park, N.S.;Kim, Y.N.;Yang, I.Y.
    • International Journal of Automotive Technology
    • /
    • v.4 no.4
    • /
    • pp.203-211
    • /
    • 2003
  • This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP (Carbon-fiber reinforced plastics) laminate plates based on considerations of stress wave propagation theory, which were converted to measurements of load and displacement verses time. The delamination area of impacted specimens for the different ply orientations was measured with an ultrasonic C-scanner to determine the correlation between impact energy and delamination area. The energy absorbed by a quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen embedding GFRP (Glass-fiber reinforced plastics) layer was higher than that of normal specimens. Also, a falling weight impact tester was built to evaluate the characteristics and impact strength of CFRPs.

Benefits of the S/F Cask Impact Limiter Weldment Imperfection

  • Ku, Jeong-Hoe;Lee, Ju-Chan;Kim, Jong-Hun;Park, Seong-Won;Park, Hyun-Soo
    • Nuclear Engineering and Technology
    • /
    • v.32 no.2
    • /
    • pp.191-203
    • /
    • 2000
  • This paper describes the beneficial effect of weldment imperfection of the cask impact limiter, by applying intermittent-weld, for impact energy absorbing behavior. From the point of view of energy absorbing efficiency of an energy absorber, it is desirable to reduce the crush load resistance and increase the deformation of the energy absorber within certain limit. This paper presents the test results of intermittent-weldment and the analysis results of cask impacts and the discussions of the improvement of impact mitigating effect by the imperfect-weldment. The rupture of imperfect weldment of an impact limiter improves the energy-absorbing efficiency by reducing the crush load amplitude without loss of total energy absorption. The beneficial effect of weldment imperfection should be considered to the cask impact limiter design.

  • PDF

Estimation of Ship Collision Energy with Bridge (교량의 선박충돌 에너지 산정)

  • Lee Seong-Lo;Kang Sung-Soo
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.416-419
    • /
    • 2004
  • The kinetic energy during ship collision with bridge piers is released as the permanent deformations of structure and friction between the impact surfaces. So the ship collision energy is estimated from the equations of motions for ship-pier collisions which include the influence of the surrounding water, different impact angles and impact locations. The normal impact energy and tangent impact energy at a collision location and angle can be transformed into the normal impact force and friction force acting on the structure. Also the kinetic energy after collisions is calculated from the linear and angular impulse of ship collisions. The collision energy absorption system such as the protective structures for bridges is designed by evaluating the damage portions of ship and structure during the ship-structure collisions varying from the soft impact to hard impact and then the estimation of it will be suited for the design of protective measures.

  • PDF

A Study on Characteristics of Impact Fracture in CFRP Laminate Plates (탄소섬유강화 복합재 적층판의 충격파괴 특성에 관한 연구)

  • Yang, I.Y.;Jung, J.A.
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.3 no.5
    • /
    • pp.38-46
    • /
    • 1995
  • In this paper, an experimental study on the effects of the impact damage and the perforation characteristic of CFRP laminates with different fiber stacking orientation and ply number was done through an observation of interrelations between the impact energy vs. transmitted energy and the impact energy vs. absorbed energy per unit volume. The velocities of the ball before or after impact are measured by the high-speed camera. And when CFRP laminates are subjected to tranverse impact by a steel ball(${\phi}10$), the delamination shapes generated by impact damage are observed by using SAM (Scanning acoustic Microscope).

  • PDF

Experimental research on dynamic response of red sandstone soil under impact loads

  • Wang, Tong;Song, Zhanping;Yang, Jianyong;Wang, Junbao;Zhang, Xuegang
    • Geomechanics and Engineering
    • /
    • v.17 no.4
    • /
    • pp.393-403
    • /
    • 2019
  • The cycling impact test of red sandstone soil under different axial pressure and different impact loads are conducted to reveal the mechanical properties and energy consumption mechanism of red sandstone soil with static-dynamic coupling loading. The results show that: Under the action of different axial pressure and different impact loads, the peak stress of the specimen increases, and then tends to be stable with the times of impact. With the increase of impact times, the specific energy absorption value of the red sandstone soil specimen is increased first and then gentle development trend. When the impact loads are certain, the larger the axial pressure is, the smaller the peak value of energy absorption, which indicates that the energy utilization rate is not high under the condition of large axial pressure. Through the analysis of energy utilization, it is found that the smaller the impact load, the higher the energy utilization rate. The greater the axial pressure, the lower the energy utilization rate. when the axial pressure is large, the impact loads corresponding to the maximum values of reflectivity, transmissivity and absorptivity are the same. The relationship between reflectivity and transmissivity is negatively correlated.

Influence of laminated orientation on the mechanical and thermal characteristics of carbon-fiber reinforced plastics

  • Shin, Hee-Jae;Kwac, Lee-Ku;Lee, Min-Sang;Kim, Hong-Gun
    • Carbon letters
    • /
    • v.16 no.4
    • /
    • pp.241-246
    • /
    • 2015
  • Rapid industrial development in recent times has increased the demand for light-weight materials with high strength and structural integrity. In this context, carbon fiber-reinforced plastic (CFRP) composite materials are being extensively used. However, laminated CFRPs develop faults during impact because CFRPs are composed of mixed carbon fiber and epoxy. Moreover, their fracturing behavior is very complicated and difficult to interpret. In this paper, the effect of the direction of lamination in CFRP on the absorbed impact energy and impact strength were evaluated, including symmetric ply (0°/0°, −15°/+15°, −30°/+30°, −45°/+45°, and −90°/+90°) and asymmetric ply (0°/15°, 0°/30°, 0°/45°, and 0°/90°), through drop-weight impact tests. Further, the thermal properties of the specimens were measured using an infrared camera. Correlations between the absorbed impact energy, impact strength, and thermal properties as determined by the drop-weight impact tests were analyzed. These analyses revealed that the absorbed impact energy of the specimens with asymmetric laminated angles was greater than that of the specimens with symmetric laminated angles. In addition, the asymmetry ply absorbed more impact energy than the symmetric ply. Finally, the absorbed impact energy was inversely proportional to the thermal characteristics of the specimens.