Papers by Keyword: Charpy Impact Test

Abstract: Polylactic acid (PLA) has become a promising material for medical implants due to its biocompatibility, biodegradability, and favorable mechanical properties. With advancements in Fused Deposition Modeling (FDM) 3D printing technology, it is possible to further optimize the performance of PLA by adjusting printing parameters. This optimization is crucial for enhancing the energy absorption and durability of PLA, especially in applications like medical implants that require reliable mechanical strength. This study utilized Response Surface Methodology (RSM) with the Box-Behnken Design (BBD) to investigate the effects of key FDM 3D printing parameters—layer thickness, infill pattern, and infill density—on the energy absorption and durability of PLA. A total of 15 experiments were conducted, with each factor tested at three levels. The standard Charpy impact test (ISO 179) was used to measure energy absorption in samples of dimensions 80x10x4 mm. This research aims to identify the key FDM 3D printing parameters that maximize the energy absorption and durability of polylactic acid (PLA) for use in medical implants, leveraging PLA's biocompatibility and mechanical properties. The study found that infill density and infill pattern are the two most critical factors affecting the energy absorption and durability of PLA. An infill density of 80% was determined to be optimal, as higher densities significantly improved energy absorption. Additionally, the grid infill pattern, combined with the highest layer thickness of 0.3 mm, provided the best performance. In conclusion, these findings offer valuable insights for optimizing PLA in medical implant applications, with potential for further refinement based on specific use cases.

Abstract: Dynamic explicit finite element (FE) analysis of the Charpy impact test was conducted in this study to investigate the inertial effect on the stress field ahead of the V-notch in a Charpy specimen. The deformation behavior of the Charpy specimen and the constraint effect on the stress field in the plastic zone near the V-notch were numerically simulated using three-dimensional FE analysis, while considering the contact of the specimen with the striker and anvil. The effect of the strain rate on the flow stress and the increase in temperature during impact loading were included in the dynamic analysis. This analysis shows that the impact load exhibits oscillation and the contact stiffness between the specimen and the striker affects the oscillation of the impact load. The analysis was validated by comparison with experimental results obtained using an instrumented Charpy impact testing machine, which measured the impact load and the load point displacement. The oscillation of the load–time curve was recorded. The magnitude and period of the peak inertia load obtained by the FE analysis were almost consistent with the experimental results. The contact stiffness between the specimen and the striker affected the stress field near the V-notch in the specimen. This indicates that the stress field in the Charpy specimen should be analyzed by the dynamic analysis procedure considering the contact stiffness based on the Hertzian contact theory.

Abstract: This work investigated the toughness behavior of polyester matrix composites reinforced with up to 30% in volume of long, continuous and aligned fibers extracted from the eucalyptus wood by means of Charpy impact tests. It was found that the addition of eucalyptus fibers results in a marked increase in the absorbed impact energy of the composites. Macroscopic observation of the post-impact specimens and SEM fracture analysis showed that longitudinal rupture through the Eucalyptus fiber interface with the polyester matrix is the main mechanism for the remarkable toughness of these composites.

Abstract: Charpy impact test is very sensitive to mechanical processing technologies and product defects. Charpy impact test can give quantitative test data and improve the product quality of advanced manufacturing industry and the safety of the application of new materials. The Charpy impact test machine has elastic deformation. The center of percussion is different from the designed center of strike and this difference can affect the vibration energy on the pendulum. In this article, by using the finite element analysis method, we simulate experimental processes having different distance to the center of percussion and obtain the numerical quantity related effects. In the end, we verify the accuracy of the finite element analysis by using different energy level impact test.

Abstract: Feasibility analysis of replacing split Hopkinson bars test by Charpy impact test for determination of Johnson-Cook’s material model parameters. The results show that the Charpy impact test may, due to the strain rates achieved, successfully replace the mentioned experimental test. Moreover the results shows that some further studies should be conducted to improve efficiency of the proposed method.

Abstract: The effect of the notch depth on the impact properties of the adhesively bonded steel butt joint under the Charpy impact test is studied using both the finite element method (FEM) and experimental method. The results obtained from numerical simulation showed that the value of the peak stress Seqv increased first and then decreased evidently when the notch depth increased from 2 mm to 8 mm. Comparing the results with that from Izod impact test, it is found that the response time retarded about 0.02 ms and the peak value of the stress Seqv decreased evidently under the Charpy impact test. The results from the experiments showed that the effect of notch depth on the impact energy absorbed by unit area of joint is as same as that from the Izod impact test.

Abstract: The objective of this work was to investigate the toughness behavior of epoxy matrix composites reinforced with up to 30% in volume of long, continuous and aligned sisal fibers by means of Charpy impact tests. The addition of sisal fibers results in a visible improvement in the energy absorption ability of the composites. Macroscopic observation of the post-impacted specimens and the SEM fracture analysis showed that longitudinal rupture through the sisal fiber interface with the epoxy matrix is the main mechanism for the higher toughness attended by these composites.

Abstract: This report described the Impact Test result and Bioactivity Properties of biodegradable Polycaprolactone (PCL) blend with nano- Montmorillonite (MMT) and Hydroxyapatite (HA). The amount of nano-MMT is varies from 2 to 4 by weight % meanwhile the amount of HA is fixed to 10 by weight percentage (wt%). The addition of nano-MMT and HA filler is to tune and indirectly improve the mechanical and bioactive properties of PCL. The samples for these test are injected from injection molding machine. The Impact test are conducted using Charpy Method. From the analysis it is found that the toughness of PCL are decreased by the addition of these fillers. PCL/MMT composites gives a better result compare to PCL/MMT/HA composites. This is due to the HA characteristic which is brilttle and tends to reduce the ductile properties of the polymer. From the Simulated Body Fluis (SBF) result, formation of apatite layer at the surface of the composites is evidence of excellent bioactivity properties of HA. The enhance of bioactivity has been proved while incorporation of HA into PCL/MMT composite. SEM-EDX image showed the bulk formation of apatite layers on the composite surface with 10 wt% HA after 3 days immersed in SBF solution.

Abstract: The Charpy V-notch test is a standardized high strain-rate test which is used to find out behaviour of materials in different temperatures by measuring the amount of energy absorption of a specimen. As a result of the Charpy V-notch test, one gets brittle-ductile transition of material. This research examines the effects of two different notch manufacturing methods on the results of impact tests performed on ultra-high-strength (UHS) steels. The goal of this study is to establish whether there is any effect on absorpted impact energy when specimens are manufactured differently and by another producer. Tested materials were bainitic-martensitic UHS steel (YS/TS 960/1000), S650MC HS steel and abrasion-resistant steel (ARS) with a hardness of 500 HBW. Impact test samples were manufactured by two different milling tools by another producer. The dimensions of the samples were measured after manufacturing. Impact test samples were tested at +20, -40 and -100 degrees Celsius with a Zwick Roell PSW750 –instrumented impact test hammer. Specimens were made in T-L orientation. Samples were impacted with 450 J. The results show that there was some difference between the used tools in the absorpted energy of the specimens.

Abstract: Prolonged high temperature exposure of welded C-Mn steels is likely to cause microstructural changes leading to an inrease in the ductile-to-brittle transition temperature (DBTT) of the welded joint. Consequently, such degrading material properties should be quantified in view of establishing accurate component life prediction model. This study examined effects of isothermal aging on DBTT behavior of the heat affected zone (HAZ) in welded Type A516 Gr 70 steels. Microstructures of the as-received weld region revealed the presence of pearlite and ferrite in the base metal while upper and lower bainite are found in the HAZ and weld metal, respectively. Hardness measures for the weld metal region, HAZ and base steel are 172, 209 and 150, respectively. Aging at 420 oC, 500 hours lowers hardness value of the HAZ by 20 %. A series of Charpy impact tests on V-notched specimens are performed for as-received and thermally aged samples at 420 oC for 500, 800 and 1200 hours. Results showed that the absorbed impact energy displays a sigmoidal variation with test temperatures. DBTT ranges from -60 to 5 oC for HAZ while narrow range from -25 to 12 oC for weld metal region. Absorbed impact energy variations in samples aged for durations up to 800 hours display another saturation level over test temperatures between -30 to 10 oC. Fractographic analysis on HAZ fracture surface indicated brittle fracture at -60 oC while ductile failure dominated at 27.7 oC. A mix-mode fracture mechanism is displayed for test conducted at -38 oC.