ORALS

SESSION: ManufacturingMonPM1-R4 Advanced Manufacturing / Mechanics / Structural Plasticity	Mamalis International Symposium on Advanced Manufacturing of Advanced Materials and Structures with Sustainable Industrial Applications
Mon Nov, 5 2018 / Room: Sao Conrado (50/2nd)
Session Chairs: Pengwan Chen; Session Monitor: TBA

14:25: [ManufacturingMonPM106]
Dynamic Compressive Behavior of An E-Glass/Polyester Composite Material Subjected to Repeated Loads
Alper Tasdemirci¹ ; Mesut Bayhan¹ ; Semih Berk Seven¹ ; Ayda Ramyar¹ ; Mustafa Guden¹ ; ¹İzmir Institute of Technology, İzmir, Turkey;
Paper Id: 124 [Abstract]

Composite materials are generally used as spall liner of the vehicle hull in military applications to protect the cabin crew from injuries [1]. In these applications, composite materials may be subjected to single or multiple impact loads. There are several studies on single loading impact events, but very few studies focused on repeated loadings. To determine the multi hit protection capability of materials using Split Hopkinson Pressure Bar (SHPB), Chen and Luo modified the conventional SHPB apparatus to deform ceramic specimen using two consecutive stress pulses [2]. Xia et al. performed an experimental study on OFHC Copper materials using stuffed strikers [3]. Rachel et al. conducted a study on copper and iron using a single striker bar formed two rods of dissimilar materials [4]. Bazle et al. carried out ballistic tests to obtain the multi hit capacity of S-2 glass/SC15 thick section composites [5]. In this study, multi-hit compressive behavior of a composite material was investigated both experimentally and numerically in the through-thickness direction. Repeated loading tests were carried out using the SHPB set-up, and LS-DYNA was used to simulate the tests numerically. To understand the failure mechanisms and damage progression, MAT_162 material model was selected. DYNAIN method was used to model the multiple impacts. This method allows to incorporate the damage attained in the specimen occurred during the first impact in the numerical model of the subsequent loadings. It was observed that delamination was occurred between the layers at regions particularly close to the specimen-incident bar interface. After the second hit, matrix damage propagated along the interfaces and the composite failed catastrophically. Experimental and numerical results showed close agreement in terms of failure mechanisms and damage initiation/progression. The numerical model can successfully predict the amount of strength decrease between the repeated loadings.

References:
[1] R. A. Ash, "9 - Vehicle armor A2 - Bhatnagar, Ashok," in Lightweight Ballistic Composites (Second Edition), ed: Woodhead Publishing, 2016, pp. 285-309.
[2] W. Chen and H. Luo, "Dynamic compressive responses of intact and damaged ceramics from a single split Hopkinson pressure bar experiment," Experimental Mechanics, vol. 44, pp. 295-299, Jun 2004.
[3] K. Xia, R. Chen, S. Huang, and S. N Luo, Controlled multipulse loading with a stuffed striker in classical split Hopkinson pressure bar testing vol. 79, 2008.
[4] R. E. Briggs, D. R. Drodge, D. M. Williamson, and W. G. Proud, "TWO-STEP LOADING IN A SPLIT HOPKINSON PRESSURE BAR," AIP Conference Proceedings, vol. 955, pp. 1173-1176, 2007.
[5] Z. H. Bazle, L. H. Jessica, and John W Gillespie, Jr., "Multi-hit ballistic impact on S-2 glass/SC15 thick-section composites: experiments," The Journal of Strain Analysis for Engineering Design, vol. 47, pp. 480-494, 2012/10/01 2012.

SESSION: ManufacturingMonPM1-R4 Advanced Manufacturing / Mechanics / Structural Plasticity	Mamalis International Symposium on Advanced Manufacturing of Advanced Materials and Structures with Sustainable Industrial Applications
Mon Nov, 5 2018 / Room: Sao Conrado (50/2nd)
Session Chairs: Pengwan Chen; Session Monitor: TBA

14:50: [ManufacturingMonPM107]
The Investigation of Low-velocity Drop Weight Impact on Concrete Plates
Alper Tasdemirci¹ ; Semih Berk Seven¹ ; Mehmet Alper Cankaya² ; Cetin Uysal³ ; Selcuk Saatci³ ; Mustafa Guden¹ ; ¹İzmir Institute of Technology, İzmir, Turkey; ²Izmir Katip Celebi University, Izmir, Turkey; ³Izmir Institute of Technology, Izmir, Turkey;
Paper Id: 123 [Abstract]

Concrete is used as a structural material which has a very wide range of applications. Concrete structures may be exposed to a variety of static and dynamic loading conditions in their lifespan. Due to this reason, it is important to investigate and understand the mechanical behavior of concrete under different impact conditions. In literature, the drop weight testing machine was used to investigate the impact behavior of different kind of cementitious material under low-velocity impact [1]. Perforation tests were performed using circular plain and fiber reinforced concrete [2]. In this study, drop weight impact tests on prismatic concrete plates were accomplished using drop tower test apparatus and modeled using finite element software LS-DYNA. In numerical analysis, JOHNSON_HOLMQUIST_CONCRETE (MAT_111) material model was selected to define material model for concrete samples since this material model is well suited for concrete materials subjected to impact loadings [3]. The dynamic mechanical characterization study of concrete material to determine the parameters of the HJC material model was done in the previous work [4]. The test setup consists of 20 mm diameter hemispherical striker tip impacting on a 200x200x20 mm prismatic specimen with the 100 mm hollow specimen holder. To see the effect of striker impact velocity on the behavior of concrete, two different impact velocities (1 m/s and 3 m/s) were applied. The effectiveness of the HJC material model and the validation of the parameters used in the numerical analysis were presented with the comparative study. The results obtained from experimental tests are in a good agreement with the numerical analysis results. Also, numerical results showed similar crack profiles with the experimental results.

References:
[1] N. Banthia, S. Mindess, A. Bentur, and M. Pigeon, "Impact Testing of Concrete Using a Drop-Weight Impact Machine Impact Testing of Concrete Using a Drop-weight Impact Machine," vol. 1106, no. March, pp. 63-69, 1989.
[2] S. Mindess and C. Yan, "Perforation of plain and fibre reinforced concretes subjected to low-velocity impact loading," Cem. Concr. Res., vol. 23, no. 1, pp. 83-92, 1993.
[3] T. J. Holmquist, G. R. Johnson, and W. H. Cook, "A computational constitutive model for concrete subjected to large strains, high strain rates, and high pressures.pdf," 14th International Symposium on Ballistic, Quebec City, Canada. pp. 1-10, 1993.
[4] A. Tasdemirci, M. A. Cankaya, S. B. Seven, C. Uysal, S. Saatci, M. Guden "The effect of strain rate on the compressive mechanical behavior of concrete," Int. J. Impact Eng., vol. under review, 2018.