Papers by Keyword: Drop Weight Impact Test

Abstract: This study deals with high-density polyethylene (HDPE) which was put to the drop weight and tensile impact tests. HDPE is a semicrystalline thermoplastic polymer which is used in common applications such as packaging, consumer goods and car tanks. The injection moulded HDPE samples were subjected the drop weight impact test at different potential energies and the results were subsequently evaluated and discussed. The second test was performed on pendulum test machine where impact resistance in tensile was studied. It was found out that HDPE is a low-cost material with high-performance properties in the field of the impact resistance which was evaluated in penetration and tensile test where the plastic deformation creates.

Abstract: The construction industry has seen an incredibly fast increase in utilizing natural fibres for making low-cost building materials to achieve sustainable construction. One of such applications is natural fibre-reinforced cementitious materials for either structural or non-structural purpose. Impact properties are engineering properties received increasing attentions from engineering community for structural materials. This research therefore studies impact resistance of hemp fibre reinforced cementitious composites at early ages. Hemp fibre with various lengths, 10 mm and 20 mm, are utilized to reinforce cementitious materials. Hemp fibre reinforced cementitious composite slabs were tested under repeating dropping mass till failure at the age of 7, 14 and 28 days. Cracking behaviour, impact resistance, absorbed impact energy and survived impact blows upon failure are qualitatively/quantitatively analysed. It has been found that 20 mm-long hemp fibre reinforcement leads to higher impact resistance, more absorbed impact energy and survived more impact blows upon failure. Cementitious composite slabs reinforced by 20 mm-long hemp fibres exhibit higher impact crack resistance ratio than those reinforced by 10 mm-long fibres. Longer fibres are more effective in inhibiting the growth of micro-cracks and blunting the propagation of micro-cracks before they join up to form macro cracks leading to ultimate failure.

Abstract: PVA fiber reinforced cement-based composite is a new high-performance cement-based composite material, which usually manufactured with PVA short fibers (does not exceed 2.5% vol.) and cement-based matrix. It has a significant strain-hardening characteristic and excellent crack controlling ability. Its ultimate tensile strain is up to 3% and crack width is not exceed 100μm. PVA fiber reinforced cement-based composite can be utilized to fabricated high energy absorption opponents, such as protective shield, seismic joint, impact-resistant site, etc. In this paper, the basic mechanical properties of PVA fiber reinforced cement-based composite has been tested and verified first. Then the impact resistance of PVA reinforced cement-based composite has been investigated via drop weight impact test, and compared with ones of plain concrete and steel fiber reinforced concrete with the same strength grade. Through analyzing the test results, it is concluded that PVA reinforced cement-based composite’s impact energy absorption is 48 times than plain concrete, and 9 times than steel fiber reinforced concrete respectively. The impact numbers of PVA reinforced cement-based composite is slightly lower than steel fiber reinforced concrete, but its impact absorption energy after initial cracking is 15 times than steel fiber reinforced concrete. In conclusion, PVA reinforced cement-based composite is an excellent impact material.

Abstract: This paper presents experimental and numerical simulation for deformation and fatigue life prediction of various cables, such as electrical, optical and network cables. The cable damage is produced by the tensile, bending and torsional action under moving and fixing condition, and by direct external impact. To obtain material responses of the cable, uniaxial tensile tests and drop-weight impact tests were adopted, and the nonlinear constitutive equations based on various strain energy potentials or material models were employed to analyze deformation of polymer sheath and metallic armor layer of the cable. Finite element results were compared with experimental data for deformation and impact absorption energy of the cable during direct external impact. Also, fatigue strength of the cable was predicted from variation of calculated stress level under tensile conditions. Fractured surface of the cable were analyzed by scanning electron microscopy (SEM).

Abstract: Impact behaviors of Aluminum Honeycombs Sandwich Panel (AHSP) by drop weight test were investigated in this study. Two types of specimens with l/2" and l/4" cell size were tested by two impactors with the weight of 5.25kgf and 11.9kgf respectively. Transient, contact and elastic-plastic analyses were performed by finite element method. Impact behavior of AHSP about impact sites appeared nearly the same in low impact energy, but it was different in high impact energy. Face was the strongest about impact and short-edge was the weakest. The damaged area of AHSP was enlarged with the increase of impactor weight that is corresponding to impact energy. After 3-point bending test, fracture modes of AHSP were analyzed with AE counts, lower face sheet was fractured in the long-edge direction first, and then separation between face sheet and core happened. In the short-edge direction after core wrinkled, lower face sheet was torn, impact behavior by FE analysis were increased localized damage in high velocity because the faster velocity of the impact was, the smaller the stress of core was. Consequently, impactor weight had an effect on widely damaged area, while the impact velocity gave rise to localized damaged area.