Journal articles: 'Impact damage'

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Schimmer, Florian, Sven Ladewig, Nicole Motsch, Joachim M. Hausmann, and Ingo Ehrlich. "Comparison of Low-Velocity Impact Damage Behavior of Unidirectional Carbon Fiber-Reinforced Thermoset and Thermoplastic Composites." Key Engineering Materials 809 (June 2019): 9–14. http://dx.doi.org/10.4028/www.scientific.net/kem.809.9.

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This paper investigates the damage behavior of thermoset and thermoplastic fiber-reinforced composites. The specimens were subjected to low-velocity impacts (LVI) to produce barely visible impact damages (BVID). To compare the dependency of the matrix system and the laminate lay-up on the impact damage, four test series were set up. Therefore, laminates with an epoxy (EP) and a polyether ether ketone (PEEK) matrix in a quasi-isotropic (QI) [+45/0/-45/90]2s and an orthotropic (OT) fiber lay-up [0/90]4s were manufactured. To eliminate the influence of variant fiber systems, the thermoplastic tape and the thermoset prepreg contain similar carbon fibers (CF). After impact testing with three different impact energies, inner damages were investigated by using ultrasonic analyses. To get a deeper understanding of the interior damage mechanisms, cross sections of the damaged areas were examined via reflected light microscopy. By using these destructive and non-destructive test methods, significant differences in the damage behavior of composites with thermoplastic and thermoset matrix systems were identified for both laminate lay-ups.

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Henkel, Ralf R., and Daniel R. Franken. "Sperm DNA Fragmentation: Origin and Impact on Human Reproduction." Journal of Reproductive and Stem Cell Biotechnology 2, no. 2 (December 2011): 88–108. http://dx.doi.org/10.1177/205891581100200204.

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Sperm DNA can be damaged due to a multitude of different noxae, which include disease, and occupational and environmental factors. Depending on the magnitude of the damage, such lesions may be repaired by the oocyte or the embryo. If this is not possible, a permanent damage can be manifested leading to mutations of the male genome. In cases where the oocyte or the embryo does not counter these damages to the male genome in terms of repair or an early abortion, sperm DNA damage and fragmentation can be a cause of numerous diseases including childhood cancer.

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Miśkiewicz, Mikołaj, Dawid Bruski, Jacek Chróścielewski, and Krzysztof Wilde. "Improvement of the load capacity of the road overpass as a result of repairs after breakage caused by vehicle impacts." MATEC Web of Conferences 284 (2019): 01004. http://dx.doi.org/10.1051/matecconf/201928401004.

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Damages of spans of the overpass caused by impact of underpassing vehicles are relatively frequent. Objects that use prefabricated load-bearing elements that are not designed for such impacts are particularly exposed. After impact, such structural elements suffer extensive damage that must be repaired. Taking advantages of this recovery actions it is worth to perform strengthening that will protect object against possible future impacts. In this study the influence of the structural strengthening of the damaged overpass on its strength parameters is investigated. For this purpose the advanced computational model was created. The numerical model includes the response of the reinforcement and prestressing tendons. This model enables precise description of damage caused due to the vehicle‘s impact and further analysis of re-impact of the strengthened structure.

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Blahovec, J. "Impact induced mechanical damage of Agria potato tubers." Research in Agricultural Engineering 51, No. 2 (February 7, 2012): 39–43. http://dx.doi.org/10.17221/4900-rae.

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Potato variety Agria was cultivated in different fertilisation and/or irrigation regimes. Tuber damage after impact was studied two months after the harvest with aim to find some relation between the regime of cultivation and impact test tuber damage. It was found that tuber cracking and/or crushing belongs to the most frequent mechanisms of damage masking usual bruising in many cases. Most severe tuber cracking was observed for cultivation with irrigation and classical methods of fertilisation. On the other hand, bruising was most frequent in case without any irrigation and fertilisation and in cases used for fertilisation the pig slurry. In every cultivation regime the bruising was more pronounced in narrower tuber side in comparison to the wider flat side.

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Katunin, Andrzej, and Pawel Kostka. "Characterisation of Impact Damage of Composite Structures Using Wavelet-Based Fusion of Ultrasonic and Optical Images." Advanced Composites Letters 23, no. 5 (September 2014): 096369351402300. http://dx.doi.org/10.1177/096369351402300504.

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This paper presents the novel approach for the impact damage characterisation of composite structures, which is based on fusion of ultrasonic scans and optical images. Both internal (inter-fibre failure, fibre failure, delaminations) and external (scratches and surface cracks) damages occurred in the composite structures during their operation need to be analysed due to their occurrence on both of these levels, especially in the case of impact damages. The presented approach allows for the improvement of the characterisation quality, i.e. the whole damaged area could be detected and localized. In order to assure the proper damage identification the wavelet-based fusion with application of appropriate wavelets and parameters of a fusion algorithm was used, which allows for distinction of different types of damages and overall improvement of the resulted image with respect to the human perception capability. The approach was validated experimentally on the glass-epoxy laminated plates after the low-velocity impacts. Representative cases of damaged structure were presented and analysed.

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Zaleha, M., Shahruddin Mahzan, and M. I. Idris. "Passive Damage Detection of Natural Fibre Reinforced Composites Using Sensor Response Data." Applied Mechanics and Materials 534 (February 2014): 17–23. http://dx.doi.org/10.4028/www.scientific.net/amm.534.17.

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This paper presents the detection of impact damage in a natural fibre reinforced composite plate under low velocity impact damage. Lead Zirconate Titanate (PZT) sensors were placed at ten different positions on each plate in order to record the response signals. The response signals captured from each sensor were collected for impacts performed by a data acquisition system. The impacted plates were examined with optical microscope to examine the damaged areas. It was found that the damaged size grew proportionally with impact force. The results also revealed that PZT sensors can be used to detect the damage extent with the waveform of sensor signals implying the damage initiation and propagation which detected above the damage force of 150N.

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Suchomel, Josef, Jan Šipoš, Ladislav Čepelka, and Marta Heroldová. "Impact of Microtus arvalis and Lepus europaeus on apple trees by trunk bark gnawing." Plant Protection Science 55, No. 2 (February 17, 2019): 142–47. http://dx.doi.org/10.17221/64/2018-pps.

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A unique evaluation of the apple tree trunk bark damage caused by common vole and European hare was presented. Damage was found in an apple orchard under organic farming, in Central Moravia (Czech Republic), at 700 m a.s.l. There were two cultivated apple cultivars Red Spring and Melodie/Angold. Damage occurred in winter with the snow cover lasting from December to February. In total 1 012 trees and 95.7% of trees were damaged. The cv. Red Spring was damaged more than cv. Melodie/Angold. Almost 90% of the dead trees were killed by common voles. While hares damaged both cultivars equally, voles damaged the cv. Red Spring to a significantly greater extent (P = 0.04). The study confirms the need of further research on the development of methodologies for orchard protection from damage caused by small mammals.

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Verma, Amrit Shankar, Nils Petter Vedvik, Zhen Gao, Saullo G. P. Castro, and Julie J. E. Teuwen. "Bondline Thickness Effects on Damage Tolerance of Adhesive Joints Subjected to Localized Impact Damages: Application to Leading Edge of Wind Turbine Blades." Materials 14, no. 24 (December 8, 2021): 7526. http://dx.doi.org/10.3390/ma14247526.

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The leading edges of wind turbine blades are adhesively bonded composite sections that are susceptible to impact loads during offshore installation. The impact loads can cause localized damages at the leading edges that necessitate damage tolerance assessment. However, owing to the complex material combinations together with varying bondline thicknesses along the leading edges, damage tolerance investigation of blades at full scale is challenging and costly. In the current paper, we design a coupon scale test procedure for investigating bondline thickness effects on damage tolerance of joints after being subjected to localized impact damages. Joints with bondline thicknesses (0.6 mm, 1.6 mm, and 2.6 mm) are subjected to varying level of impact energies (5 J, 10 J, and 15 J), and the dominant failure modes are identified together with analysis of impact kinematics. The damaged joints are further tested under tensile lap shear and their failure loads are compared to the intact values. The results show that for a given impact energy, the largest damage area was obtained for the thickest joint. In addition, the joints with the thinnest bondline thicknesses displayed the highest failure loads post impact, and therefore the greatest damage tolerance. For some of the thin joints, mechanical interlocking effects at the bondline interface increased the failure load of the joints by 20%. All in all, the coupon scale tests indicate no significant reduction in failure loads due to impact, hence contributing to the question of acceptable localized damage, i.e., damage tolerance with respect to static strength of the whole blade.

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Wang, Kai Lun, Zhi Dong Guan, Jun Guo, and Zeng Shan Li. "Impact Damage Resistance of Thin-Core Sandwich Structures Subjected to Low-Velocity Impact." Applied Mechanics and Materials 684 (October 2014): 176–81. http://dx.doi.org/10.4028/www.scientific.net/amm.684.176.

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This paper aims at evaluating the damage resistance of thin core sandwich structures, composed of aramid paper honeycomb core and carbon/ epoxy laminates face-sheets subjected to low velocity impact. The impact tests are performed using the instrumented impact-testing machine and resulting impact damages are inspected by Ultrasonic C-scan. In order to study the failure process of the core, which is important in the damage of the structures, flatwise compression test was carried out. Four parameters have been analyzed as follows: maximum load, total energy absorbed during impact, impact dent depth, and impact damage area. Nearly all impact force histories of panels have “twin peaks”, but the second peak of the 3mm-core structure is much larger than the first, which is quite different from others, when impact energy reached 5J, which were caused by the thickness of the core. Impact damages of thin-core sandwich structures are mainly delamination in the face-sheet and core crushing at low energy, and fiber breakage at relatively high energy. The damage processes of different groups of structures are essentially different and the impact resistance of the sandwich structure is greatly influenced by the face-sheet and core thickness.

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N. L. Schulte, G. K. Brown, and E. J. Timm. "Apple Impact Damage Thresholds." Applied Engineering in Agriculture 8, no. 1 (1992): 55–60. http://dx.doi.org/10.13031/2013.26033.

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R. Mathew and G. M. Hyde. "POTATO IMPACT DAMAGE THRESHOLDS." Transactions of the ASAE 40, no. 3 (1997): 705–9. http://dx.doi.org/10.13031/2013.21290.

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Ritter, J. E. "Spherical Particle Impact Damage." Key Engineering Materials 71 (January 1992): 107–20. http://dx.doi.org/10.4028/www.scientific.net/kem.71.107.

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Adler, William F. "Particulate impact damage predictions." Wear 186-187 (July 1995): 35–44. http://dx.doi.org/10.1016/0043-1648(95)07177-6.

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Sator, N., and H. Hietala. "Damage in impact fragmentation." International Journal of Fracture 163, no. 1-2 (September 29, 2009): 101–8. http://dx.doi.org/10.1007/s10704-009-9406-8.

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Guo, Xiaohui. "Sandstone Impact Damage Study." Academic Journal of Science and Technology 5, no. 3 (April 22, 2023): 21–26. http://dx.doi.org/10.54097/ajst.v5i3.7351.

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In order to study the impact of impact on sandstone, dynamic impact is conducted on sandstone through drop hammer test, wave velocity test is conducted on the impacted specimen by using wave velocity instrument, and the damage effect of impact on sandstone is analyzed by using wave velocity damage calculation formula. The results show that the greater the impact velocity, the smaller the measured wave velocity and the greater the damage to the sandstone.

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Wang, Yitao, Teng Zhang, Yuting He, Jiyuan Ye, Hanzhe Zhang, and Xianghong Fan. "Analysis of Damage of Typical Composite/Metal Connecting Structure in Aircraft under the Influences of High-Velocity Fragments." Applied Sciences 12, no. 18 (September 15, 2022): 9268. http://dx.doi.org/10.3390/app12189268.

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A two-stage light gas gun was used to conduct a high-velocity impact test on the aircraft’s typical composite/metal connecting structure (CFRP/AL). The battle damage simulations used for the CFRP/AL connecting structure were carried out under different intersection conditions. Then, the damage morphology and mechanism of high-velocity prefabricated spherical fragments on typical structures, the dynamic process of hyper-velocity impact, and the formation of debris clouds on the secondary damage morphology of different component structures were investigated. Next, based on the X-ray computerized tomography (CT), the typical mode of different damage areas and evolution trends of CFRP under high-velocity impacts were explored. Finally, a simulation model was established for battle damages of typical structures by combining FEM methods, and structural components’ energy dissipation capabilities for fragments under different velocities were analyzed. The study results provide a reference and model support for the rapid repair of battle-damaged aircraft and aircraft survivability design.

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Mouhoubi, Said, and Krimo Azouaoui. "Residual properties of composite plates subjected to impact fatigue." Journal of Composite Materials 53, no. 6 (August 1, 2018): 799–817. http://dx.doi.org/10.1177/0021998318791324.

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This work deals with post-impact residual mechanical behavior of composite plates made with glass fiber cloth and two different thermosetting resins (epoxy and polyester). It is well known that damages induced by multiple impacts greatly reduce the residual properties. How are the residual strength or stiffness affected by the impacts? How does impact energy and number of impacts contribute to the degradation of mechanical properties? What kind of supports induces more damages and consequently a larger reduction in residual properties? These are some questions that we attempt to clarify in this paper. To investigate and assess the effect of the energy level and number of impacts on the total induced damage and residual properties, impact fatigue tests were carried out at selected energy range of: 3 J, 4 J, 5 J, and 6 J. Then, coupons containing the damaged area are cut out, in order to estimate the tensile, compressive, and shear residual properties, particularly residual strength. The energy level and number of impacts are major factors influencing the loss of stiffness and strength. However, stiffness is more affected than strength by the repeated impacts. A clear decrease of compressive residual strength with the number of impacts for the two fixture conditions (clamped on two opposite sides and a circular clamp) is demonstrated. The drop in the case of the circular clamping is more visible, confirming a greater extent of damages. A three-parameter damage model is proposed and applied, with some conclusions are withdrawn in this investigation.

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Touchard, Fabienne, Michel Boustie, Laurence Chocinski-Arnault, Pedro Pascual González, Laurent Berthe, Davi de Vasconcellos, Luigi Sorrentino, Pawel Malinowski, and Wieslaw Ostachowicz. "Mechanical and laser impact effects on woven composites with hemp or glass fibres." International Journal of Structural Integrity 8, no. 3 (June 12, 2017): 286–307. http://dx.doi.org/10.1108/ijsi-06-2016-0022.

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Purpose The purpose of this paper is to study the damage induced in “green” and synthetic composites under impact loading. Design/methodology/approach The study was focussed on epoxy-based composites reinforced with woven hemp or glass fibres. Six assessment techniques were employed in order to analyse and compare impact damages: eye observation, back face relief, terahertz spectroscopy, laser vibrometry, x-ray micro-tomography and microscopic observations. Findings Different damage detection thresholds for each material and technique were obtained. Damage induced by mechanical and laser impacts showed relevant differences, but the damage mechanisms are similar in both types of impact: matrix cracks, fibre failure, debonding at the fibres/matrix interface and delamination. Damage shape on back surfaces is similar after mechanical or laser impacts, but differences were detected inside samples. Originality/value The combination of these six diagnoses provides complementary information on the damage induced by mechanical or laser impacts in the studied green and synthetic composites.

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Chen, An, Weifeng Zang, and Lei Li. "Shear Strength of Honeycomb Sandwich Panel with Impact Damage." Journal of Physics: Conference Series 2541, no. 1 (July 1, 2023): 012021. http://dx.doi.org/10.1088/1742-6596/2541/1/012021.

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Abstract Impact damage may reduce the mechanical property of honeycomb sandwich composites. In this paper, the impact damage and post-impact shear behavior of honeycomb sandwich plates are studied experimentally. The same impact damage energy was applied to all six test specimens. The damage region and depth of the impact crater were measured by using equipment. Shear tests were conducted on intact and damaged specimens to compare their strain fields and failure modes. The results show that there were no buckling phenomenon in the skin occurred both in intact and damaged specimens during the whole shear experiment. The failure mode of the pristine specimens is different from that of damaged specimens. The shear failure load after impact decreases by 17.1% compared to the non-impact panel. This leads to the conclusion that the impact damage worsens the mechanical property of the honeycomb composite panel and has a great effect on it.

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Britto, Pedro C., Dirk Jaeger, Stephan Hoffmann, Renato C. G. Robert, Alexander C. Vibrans, and Alfredo C. Fantini. "Feasibility of Sustainable Management of Secondary Atlantic Forest: Recovery and Mortality Rates of Damaged Trees Two Years After Harvesting." Environmental Sciences Proceedings 3, no. 1 (November 20, 2020): 39. http://dx.doi.org/10.3390/iecf2020-08484.

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Subject to overexploitation in past centuries, the Atlantic Forest is now strictly protected, including a ban on timber harvesting. However, this strict protection is a very controversial issue. It resulted in a lack of willingness of landholders to conserve and possibly even expand native forest areas. The lack of knowledge on impacts of potential timber-harvesting causes conflicts between conservation and management of the remnant Atlantic Forest. We believe that sustainable forest management, with reduced harvesting impact, has the potential to generate income for the landowners while sustaining important ecological services of the forest. Therefore, we assessed the harvesting impact of a conventional harvesting method (CM) and compared it to an alternative harvesting method (AM) in three different stands. We measured damage intensities of all remnant trees directly after harvesting and two years after harvesting. Tree damages were recorded in three different tree zones (crown, bole and leaning) and rated in three different intensity classes (minor, moderate and severe). Furthermore, we assessed the recovery and mortality rates of each damaged tree two years after harvesting. Improved AM harvesting reduced the impacts on trees with multiple damages, in particular to crown and bole damages combined. There is a strong relationship between steep terrains and crown damage. High mortality rates were related to stands with a high density of smaller trees and also to trees with leaning damage. Moreover, completely recovered trees were related to trees with light bole damage.

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Snepsts, Guntars, Mara Kitenberga, Didzis Elferts, Janis Donis, and Aris Jansons. "Stem Damage Modifies the Impact of Wind on Norway Spruces." Forests 11, no. 4 (April 19, 2020): 463. http://dx.doi.org/10.3390/f11040463.

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Bark stripping caused by cervids can have a long-lasting negative effect on tree vitality. Such trees of low vitality might be more susceptible to other disturbances. The amplifying effects of disturbance interactions can cause significantly more damage to forest ecosystems than the individual effects of each disturbance. Therefore, this study aimed to assess the impact of bark stripping (stem damage) on the probability of wind damage and snapping height for Norway spruces (Picea Abies (L.) H. Karst.). In this study, we used the Latvian National Forest Inventory data from the period 2004–2018. In the analysis, we used data based on 32,856 trees. To analyse the data, we implemented a Bayesian binary logistic generalised linear mixed-effects model and the linear mixed-effects model. Our results showed that stem damage significantly increased the probability of wind damage and affected the snapping height of Norway spruces. Similarly, root damage, the slenderness ratio, the stand age, the stand density, the soil type, and the dominant tree species had a significant influence on the probability of wind damage. In both periods, trees with stem damage had significantly (p < 0.05) higher probability (odd ratio 1.68) to be wind damaged than trees without stem damage. The stem damaged Norway spruce trees snapped in the first 25% of the tree height, while trees without stem damage snapped around half (50%) of the tree height. Our results show that stem damage significantly alters the effect of wind damage on Norway spruces, suggesting that such damage must be incorporated into wind-risk assessment models.

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Wang, Feng, Haibo Wang, Ying Xu, Bing Cheng, and Qianqian Wang. "Analysis of Energy Dissipation Characteristics of Damaged Sandstone under Impact Load." Shock and Vibration 2021 (July 22, 2021): 1–10. http://dx.doi.org/10.1155/2021/4200452.

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Before rock burst, coal, and gas outburst dynamic load, rock mass in geotechnical engineering has been an indifferent degree of damage. The dissipation energy of rock mass under dynamic load reflects the difficulty of rock breaking. In view of the energy dissipation of damaged rock mass under dynamic load, the cyclic loading and unloading test is carried out to make sandstone in different damage states, and the damage degree of sandstone is characterized by the change of longitudinal wave velocity before and after cyclic loading and unloading. Then, the rock with different damage degrees is tested by adopting the split Hopkinson pressure bar (SHPB). Finally, the energy dissipation characteristics of damaged rock under impact load are analyzed. The results show that the damage factor of sandstone increases with the increase of the upper limit of stress after cyclic static loading. The dynamic strength and peak strain of damaged sandstone increase with the increase of impact pressure and decrease with the increase of damage degree. With the increase of damage degree of sandstone, the reflection energy and dissipation energy of sandstone increase, while the transmission energy decreases.

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Abrate, Serge. "Impact on Laminated Composites: Recent Advances." Applied Mechanics Reviews 47, no. 11 (November 1, 1994): 517–44. http://dx.doi.org/10.1115/1.3111065.

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Impact damage in structures made out of composite materials is a major concern since such damage can be introduced during the life of the structure, and its mechanical properties can be drastically reduced as a result. In a previous review of the literature on impact on composite materials, this author considered 285 published before 1989. In this article over 300 articles most of which appeared after 1989 are reviewed. These figures indicate that this is a very active area of research, and the present paper seeks to present a comprehensive view of the latest developments. Taken together, these two reviews present a comprehensive view of the state of knowledge in the area. Most the current research effort is focused on low velocity impact damage and, in particular, the damage predictions and the evaluation and prediction of residual properties of damaged laminates. A significant number of papers deal with ballistic impacts on laminated composites and the use of composite materials in designing light armor.

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Nyman, Tonny, Anders Bredberg, and Joakim Schon. "Equivalent Damage and Residual Strength for Impact Damaged Composite Structures." Journal of Reinforced Plastics and Composites 19, no. 6 (April 2000): 428–48. http://dx.doi.org/10.1177/073168440001900601.

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NYMAN, TONNY, ANDERS BREDBERG, and JOAKIM SCHON. "Equivalent Damage and Residual Strength for Impact Damaged Composite Structures." Journal of Reinforced Plastics and Composites 19, no. 6 (January 1, 2000): 428–48. http://dx.doi.org/10.1106/5c3a-0mnm-phlb-t96f.

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Kubiak, Tomasz, Lukasz Borkowski, and Nina Wiacek. "Experimental Investigations of Impact Damage Influence on Behavior of Thin-Walled Composite Beam Subjected to Pure Bending." Materials 12, no. 7 (April 6, 2019): 1127. http://dx.doi.org/10.3390/ma12071127.

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The paper deals with buckling, postbuckling, and failure of pre-damaged channel section beam subjected to pure bending. The channel section beams made of eight-layered GFRP laminate with different symmetrical layups have been considered. The specimens with initially pre-damaged web or flange were investigated to access the influence of impact damage on work of thin-walled structure in the full range of load till failure. The bending tests of initially pre-damage beams have been performed on a universal tensile machine with especially designed grips. The digital image correlation system allowing to follow the beam deflection have been employed. The experimentally obtained results are presented in graphs presenting load-deflection or load vs. angle of rotation relations and in photos presenting impact damages areas before and after bending test. The results show that the impact pre-damages have no significant influence on the work of channel section beams.

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Matemilola, S. A., and W. J. Stronge. "Low-Speed Impact Damage in Filament-Wound CFRP Composite Pressure Vessels." Journal of Pressure Vessel Technology 119, no. 4 (November 1, 1997): 435–43. http://dx.doi.org/10.1115/1.2842327.

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Quasi-static and impact tests were conducted on filament-wound carbon fiber composite pressure vessels to study factors that affect burst pressure. Observed damage included fiber microbuckling, matrix cracking, and delamination. Fiber microbuckling of the outer surface layer near the impact point was the main factor that reduced the burst pressure of the vessels. This type of damage was visually detectable on the surface. For similar levels of missile kinetic energy, the impact damage to filament-wound composite pressure vessels depends on size and shape of the colliding body in the contact area. Burst pressure for a damaged vessel decreases with the ratio of axial length of damaged fibers 1, to vessel wall thickness h, up to a ratio 1/h = 3; beyond this length of damaged section the burst pressure was independent of length of damage. Strain measurements near the region of loading showed that damage related to fiber microbuckling is sensitive to strain rate. At locations where impact damage was predominately due to fiber microbuckling, the failure strain was about six times the strain for microbuckling during quasi-static loading.

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Sawal, Nurashikin, and Md Akil Hazizan. "Effect of Core Thicknesses on Impact Performance of Thermoplastic Honeycomb Core Sandwich Structure under Low-Velocity Impact Loading." Key Engineering Materials 471-472 (February 2011): 461–65. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.461.

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Low-velocity impact test on sandwich panels composed of aluminum face sheets and thermoplastic honeycomb cores have been performed to characterize the impact performance as a function of core thickness and drop heights. Impact parameters like maximum impact force, impact energy and impact damage area were evaluated and compared. Consequent damages were inspected visually on the impact surface as well as the rear surface. The experimental results found that panels with thicker core exhibited higher impact force than thinner core counterparts, allowing the panel to absorbed more energy. Higher degree of impact damage can be observed at elevated drop heights as most of the damage took the form of local core crushing, face sheet buckling and debonding between the face sheet and core,. Resulting damage area were different according to the core thickness as thicker core prone to absorbed more energy that lead to more damage propagation.

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Bao, Guocheng, Gongpu Wang, Bing Wang, Lianglong Hu, Xiaowei Xu, Haiyang Shen, and Longlong Ji. "Study on the drop impact characteristics and impact damage mechanism of sweet potato tubers during harvest." PLOS ONE 16, no. 8 (August 24, 2021): e0255856. http://dx.doi.org/10.1371/journal.pone.0255856.

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Collision of falling in the mechanical harvesting process of sweet potato is one of the main causes of epidermal destruction and damage to sweet potato tubers. Therefore, a sweet potato mechanical characteristic test and a full-factor sweet potato drop test were designed. Based on the analysis of the fitting mathematical model, the impact of the drop height, collision material and sweet potato chunk size on the damage of the sweet potato were studied. The mathematical models were established by fitting analysis of the IBM SPSS Statistics 22 software between the drop height and the sweet potato chunk size with each test index (impact force, impact stress, broken skin area and damaged area). The critical epidermal destruction height and the critical damage height of a certain size of sweet potato when it collides with a collision material can be calculated by the mathematical model, and the critical epidermal destruction mass and critical damage mass of sweet potato when it falls from a certain height and collides with a collision material can also be calculated. Then a series of critical values (including critical epidermal destruction force value, critical epidermal destruction impact stress, critical damage force value, critical damage impact stress) of mechanical properties of sweet potato were obtained. The results show that the impact deformation of sweet potato includes both elastic and plastic ones, and has similar stress relaxation characteristics. The critical damage impact stress of sweet potato is that the average value of the impact stress on the contact surface is less than it’s Firmness. The results provided a theoretical basis for understanding the collision damage mechanism of sweet potato and how to reduce the damage during harvest.

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Wang, Weizu, Shuangming Zhang, Han Fu, Huazhong Lu, and Zhou Yang. "Evaluation of litchi impact damage degree and damage susceptibility." Computers and Electronics in Agriculture 173 (June 2020): 105409. http://dx.doi.org/10.1016/j.compag.2020.105409.

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Hu, Hao, Qiangqiang Zheng, Xin Gao, Bing Cheng, Qianqian Wang, and Xian Ni. "Fracture Characteristics and Geometric Fractal of Damaged Sandstone under Impact Load." Shock and Vibration 2020 (November 16, 2020): 1–10. http://dx.doi.org/10.1155/2020/6617197.

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Before the rock mass in the engineering is broken under load, it is usually in a state of varying degrees of damage. Aiming at the fracture characteristics of damaged sandstone under impact load, this paper adopts a method of the cyclic static load to cause the sandstone specimens to have varying degrees of damage. Then, the wave velocity of sandstone before and after the damage is measured using the nonmetallic acoustic velocimeter, and the change rule of damage factor is analyzed. Finally, the split Hopkinson pressure bar (SHPB) is used to test the impact dynamics of sandstone with different damage degrees. The broken rock block is screened by a vibrating screen, and the crushing characteristics are analyzed. The results show that not only the damage factor of damaged sandstone but the growth rate increases, with the raising upper limit of stress. Under the impact load of the same incident energy, the fragmentation degree of the damaged sandstone increases with the increase of the upper stress limit, while the average diameter of the broken rock block decreases gradually, and the reduction rate increases first and then decreases.

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Ouroua, Yacine, Said Abdi, and Imene Bachirbey. "Rupture by impact-induced fatigue of a copper foil strip embedded in a multifunctional composite material." Journal of Composite Materials 55, no. 19 (February 14, 2021): 2631–43. http://dx.doi.org/10.1177/0021998321994327.

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Multifunctional composite materials are highly sought-after by the aerospace and aeronautical industry but their performance depends on their ability to sustain various forms of damages, in particular damages due to repeated impacts. In this work we studied the mechanical behavior of a layered glass-epoxy composite with copper inserts subjected to fatigue under repeated impacts with different energy levels. Damage evolution as a function of impact energy was carefully monitored in order to determine the effect of the copper inserts on mechanical characteristics of the multifunctional composite, such as endurance and life. Results of repeated impact tests show that electric current interruption in the copper inserts occurs prior to the total perforation of the composite material, and after about 75% of the total number of impacts to failure. This is the case for the three energy levels considered in this study, [Formula: see text] = 2, 3 and 4 Joules. The epoxy resin was dissolved chemically in order to preserve the mechanical structure of the damaged copper inserts and the composite fibers for further inspection and analysis. Scanning electron microscopy (SEM) of the fractured copper inserts revealed interesting information on the nature of the damage, including information on plastic deformation, strain hardening, cracking mode, temperature increase during the impacts, and most importantly the glass fibers and their roles during the impact-fatigue tests.

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Choi, Yunshil, and Jung-Ryul Lee. "Dual-energy wave subtraction imaging for evaluation of barely visible impact damage with an ultrasonic propagation imaging system." Journal of Intelligent Material Systems and Structures 29, no. 17 (August 1, 2017): 3411–25. http://dx.doi.org/10.1177/1045389x17721040.

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Barely visible impact damage from low-velocity impacts have been studied as critical design factors of composite structures. In this article, a dual-energy wave subtraction algorithm using an ultrasonic propagation imaging system is proposed to evaluate barely visible impact damage as a strategy of fast in situ nondestructive evaluation or structural health monitoring (SHM). The ultrasonic propagation imaging system is a type of nondestructive evaluation or SHM system and is based on scanning laser-induced guided ultrasound and fixed sensors. The amplitude of ultrasonic signals generated by the ultrasonic propagation imaging system increases with the increasing energy of the laser beam. Two ultrasonic signals generated by different excitation energies of the laser beam can be equalized by multiplying a constant factor to one of them. Therefore, the residuals after subtraction of two signals may be close to zero. However, the two different energy induced signals in the damaged area will be nonzero due to the change in material conditions regarding the laser ultrasonic generation mechanism. The dual-energy wave subtraction algorithm eliminates most of the incident ultrasonic waves and amplifies anomalous waves. A composite wing skin including two barely visible impact damages as well as a composite sandwich panel, including a single barely visible impact damage, were inspected to validate the proposed algorithm.

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Schulte, Nancy L., Edward J. Timm, and Galen K. Brown. "`Redhaven' Peach Impact Damage Thresholds." HortScience 29, no. 9 (September 1994): 1052–55. http://dx.doi.org/10.21273/hortsci.29.9.1052.

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`Redhaven' peaches [Prunus persica (L.) Batsch] were dropped onto several impact surfaces to determine impact conditions that initiate bruising. After impact, the peaches were tested for flesh firmness and sorted into firm, soft, and very soft groups for bruise analysis. The drop height that did not bruise decreased as fruit softened. The peach shoulder area bruised most easily. A drop of only 8 mm onto a hard surface initiated bruising on a soft peach, whereas a Poron 15250 cushion could protect the peach for a ≤85-mm drop. Impact damage threshold estimates were developed for the three flesh firmness conditions. The threshold estimates and impact history information collected by an instrumented sphere can be used to develop handling equipment design and operation guidelines that essentially avoid impact bruises on peaches.

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35

Harding,, J. "Impact Damage in Composite Materials." Science and Engineering of Composite Materials 1, no. 2 (April 1989): 41–68. http://dx.doi.org/10.1515/secm.1989.1.2.41.

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Xia, Kaiwen, and Thomas J. Ahrens. "Impact induced damage beneath craters." Geophysical Research Letters 28, no. 18 (September 15, 2001): 3525–27. http://dx.doi.org/10.1029/2001gl013001.

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Nyoungue, A., Z. Azari, M. Abbadi, S. Dominiak, and S. Hanim. "Glass damage by impact spallation." Materials Science and Engineering: A 407, no. 1-2 (October 2005): 256–64. http://dx.doi.org/10.1016/j.msea.2005.07.031.

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38

A. D. Sharma, O. R. Kunze, and N. N. Sarker. "Impact Damage on Rough Rice." Transactions of the ASAE 35, no. 6 (1992): 1929–34. http://dx.doi.org/10.13031/2013.28817.

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James A. Bartsch, C. Gene Haugh, Kirk L. Athow, and Robert M. Peart. "Impact Damage to Soybean Seed." Transactions of the ASAE 29, no. 2 (1986): 0582–86. http://dx.doi.org/10.13031/2013.30193.

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Tennyson, R. C., and C. Lamontagne. "Hypervelocity impact damage to composites." Composites Part A: Applied Science and Manufacturing 31, no. 8 (August 2000): 785–94. http://dx.doi.org/10.1016/s1359-835x(00)00029-4.

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41

Atkinson, Dale, and Alan Watts. "Impact damage and optical scatter." International Journal of Impact Engineering 14, no. 1-4 (January 1993): 49–60. http://dx.doi.org/10.1016/0734-743x(93)90008-u.

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42

Chung-Yue, Wang, and Ching H. Yew. "Impact damage in composite laminates." Computers & Structures 37, no. 6 (January 1990): 967–82. http://dx.doi.org/10.1016/0045-7949(90)90009-q.

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Davies, G. A. O., X. Zhang, G. Zhou, and S. Watson. "Numerical modelling of impact damage." Composites 25, no. 5 (May 1994): 342–50. http://dx.doi.org/10.1016/s0010-4361(94)80004-9.

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Maekawa, I., H. S. Shin, and H. Miyata. "Particle Impact Damage on Ceramics." Key Engineering Materials 51-52 (January 1991): 173–78. http://dx.doi.org/10.4028/www.scientific.net/kem.51-52.173.

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Bless, Stephan, and Tiffany Chen. "Impact damage in layered glass." International Journal of Fracture 162, no. 1-2 (July 28, 2009): 151–58. http://dx.doi.org/10.1007/s10704-009-9379-7.

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46

Kang, Ki Weon, Jung Kyu Kim, and Heung Seob Kim. "Impact Damage and Strength Reduction Behavior of Honeycomb Sandwich Structure Subjected to Low Velocity Impact." Key Engineering Materials 306-308 (March 2006): 279–84. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.279.

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The goals of the paper are to identify the impact damage and strength reduction behavior of sandwich structure, composed of carbon/epoxy laminates skin and Nomex core with two kinds of thickness (10 and 20mm). For these, low velocity impact tests were conducted using the instrumented impact-testing machine and damages are inspected by SAM. And then, subsequent static tests are conducted under flexural loading to identify the strength reduction behavior of the impacted sandwich structures. The impact damages are mainly delamination in carbon/epoxy skin and their behavior is mostly independent of core thickness. Also, their energy absorbing behavior is identified through calculating the energy absorbed by impact damage. Finally, the strength reduction behavior is evaluated through Caprino’s model, which was proposed on the unidirectional laminates.

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Cao, Yang, Yuchen Zhang, Menghua Lin, Di Wu, and Kunsong Chen. "Non-Destructive Detection of Damaged Strawberries after Impact Based on Analyzing Volatile Organic Compounds." Sensors 22, no. 2 (January 6, 2022): 427. http://dx.doi.org/10.3390/s22020427.

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Strawberries are susceptible to mechanical damage. The detection of damaged strawberries by their volatile organic compounds (VOCs) can avoid the deficiencies of manual observation and spectral imaging technologies that cannot detect packaged fruits. In the present study, the detection of strawberries with impact damage is investigated using electronic nose (e-nose) technology. The results show that the e-nose technology can be used to detect strawberries that have suffered impact damage. The best model for detecting the extent of impact damage had a residual predictive deviation (RPD) value of 2.730, and the correct rate of the best model for identifying the damaged strawberries was 97.5%. However, the accuracy of the prediction of the occurrence time of impact was poor, and the RPD value of the best model was only 1.969. In addition, the gas chromatography–mass spectrophotometry analysis further shows that the VOCs of the strawberries changed after suffering impact damage, which was the reason why the e-nose technology could detect the damaged fruit. The above results show that the mechanical force of impact caused changes in the VOCs of strawberries and that it is possible to detect strawberries that have suffered impact damage using e-nose technology.

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Keršienė, Neringa, and Antanas Žiliukas. "INTERLAMINAR AND INTRALAMINAR DAMAGE MECHANISMS OF IMPACT RESISTANT AIRCRAFT MATERIALS UNDER LOW‐ENERGY IMPACT." Aviation 10, no. 3 (September 30, 2006): 3–8. http://dx.doi.org/10.3846/16487788.2006.9635933.

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For low-velocity impact, drop‐weight impact tests performed by EADS (European Aeronautic Defence and Space Company) Corporate Research Center Germany have been carried out for 2‐D woven E‐Glass/epoxy composite systems to determine material response as a function of absorbed energy and damaged area. Nondestructive techniques like visual inspection and analysis of impact response of the woven fabric laminates at different energy levels are utilized to assess the initiation and progression of interlaminar and intralaminar damage. The dominant damage modes for woven reinforced composite systems were found to be matrix cracking with branching into the adjacent layers, intralaminar cracking by mixture of localized matrix shear and matrix/fibre interfacial debonding, front face indentation, and back face fibre damage. The use of woven fabrics as opposed to cross‐ply unidirectional prepreg tapes is specifically discussed from the point view of microstructure and property. In the case of low‐energy impact, damage resistance under impact loading of woven and multiaxial non‐crimp fabrics is presented and compared. The assumption that shear‐response dominated for woven reinforced composite systems was found to be in good agreement with the experimental results.

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Huang, Yinyuan, Felix Thompson EShun, Junfeng Hu, Xutong Zhang, Jianping Zhao, Siqi Zhang, Rui Qian, Zhou Chen, and Dingding Chen. "Research on Low-Velocity Impact Response of Novel Short-Fiber-Reinforced Composite Laminates." Polymers 15, no. 4 (February 8, 2023): 840. http://dx.doi.org/10.3390/polym15040840.

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Short-fiber-reinforced polymers (SFRPs) based on unidirectionally arrayed chopped strands (UACSs) have excellent formability and outstanding mechanical response. The low-velocity impact response, such as the delamination, damage tolerance and energy absorption of UACS composites, are essential to guarantee the stability and safety of composite components in service. The current study investigates the low-velocity impact response of continuous carbon-fiber-reinforced polymer (CFRP) and UACS laminates with vertical slits under drop-weight impact with various impact energies (4, 7 and 11 J). The in-plane size of the studied samples is 100 mm × 100 mm, and the stacking sequence is [0/90]4s. The time–history curves of load and energy are examined during low-velocity impact experiments, as well as the nonvisible damages are obtained by ultrasound C-scan imaging technique. A user-defined subroutine VUMAT, including the Johnson–Cook material and failure model, which is used to simulate the elastic–plastic property of the slits filled with resin, is coded in ABAQUS/Explicit. According to C-scan inspections of the impact-damaged laminates, UACS specimens show more severe delamination as impact energy increases. The damaged area of continuous CFRP laminates under impact energy of 11 J is 311 mm2, while that of UACS laminates is 1230 mm2. The slits have a negative effect on the load-bearing capacity but increase the energy absorption of UACS laminates by approximately 80% compared to the continuous CFRP laminates at 7 J. According to the variables of different damage modes in numerical simulation, cracks appear at the slits and then expand along the direction perpendicular to the slits, leading to the fracture of fiber. Nevertheless, as the damage expands to the slits, the delamination confines the damage propagation. The existence of slits could guide the path of damage propagation.

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Liu, Yi Ping, Ting Hui He, Li Qun Tang, and Xiao Qing Huang. "Analysis on Coupling Damage of Liquid Rubber Based Concrete under Fatigue and Impact Loading." Key Engineering Materials 452-453 (November 2010): 481–84. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.481.

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In this paper coupling damage behaviors of Liquid Rubber Based Concrete (LRBC) are studied experimentally. Compressive fatigue and impact alternant loading tests were carried out on cylindrical LRBC specimens. The elastic moduli were recorded before and after fatigue and impact tests. The quasi-static compressive stress-strain curves after fatigue and impact tests were obtained. According to the definition of dissipated energy, the cumulating of dissipated energy was used to define damage. The analysis on impact and fatigue damages during the loading processes show that fatigue and impact loading lead to the formation and development of inner damage. During the alternant loading process, impact and fatigue damages are coupled mutually, with the former affects the evolution of fatigue damage evidently.

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Journal articles on the topic 'Impact damage'

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