PSI - Issue 6

A.A. Chevrychkina et al. / Procedia Structural Integrity 6 (2017) 283–285 Author name / Structural Integrity Procedia 00 (2017) 000–000

284

2

a)

b) Fig. 1. Geometry of a) Sample 1, b) Sample 2

rate of deformation by reducing the working part. In addition, a comparative analysis with the starting material was carried out. The obtained experimental data were described using a structurally-temporal approach.

2. Experiments

An additive material, printed from ABS plastic on a 3D printer, is considered. Samples of two types with a working part length of 5 and 10 mm were researched, the thickness of samples was 1 mm. Samples were printed in layers, layer thickness 0.06 mm. Static experimentation were conducted on Shimadzu AG-50kNX at strain rate 10 − 5 − 10 − 3 s − 1 . The values of modulus of elasticity E = 1700 GPa and tensile strength σ c = 36 . 5 MPa were determined. Values of tensile strength at strain rate 10 2 − 10 3 s − 1 were determined on Instron CEAST 9350. Fixation of signals were occurred in an automated mode using a piezoelectric force sensor and the displacement sensor of the hammer. A typical force profile versus time: the force increases linearly to its maximum value, then the force value decreases slightly and remains constant for a while, at this time in the sample processes develop that lead to destruction. The dynamic strength is the ratio of the maximum value of the force to the initial area of the cross sample. Reducing the working part of the sample leads to an increase in the strain rate at a constant impact energy. The shorter length of the working part of sample 2 allows a higher strain rate to be achieved than for sample 1 at the same impact speed. As in the case of static loading, and for dynamic loading, the value of the tensile strength for Sample 1 di ff ers little from the Sample 2. Comparison of the data for the printed material and the raw material allows us to assume that with a high quality of printing, the strength properties vary slightly. The tests carried out showed that the ultimate strength of the printed samples from ABS plastic depends significantly on the strain rate, the critical stress values increase nonlinearly with increasing strain rate. Tests of samples made of ABS plastic are carried out under quasistatic and dynamic tensile loads. The e ff ect of increasing the ultimate strength values with increasing strain rate is well described using a structurally-time approach. As a criterion of destruction is the criterion of incubation time. 1 τ c t t − τ c σ ( s ) σ c ds ≤ 1 , (1) where σ is tensile stress, it increases linearly with time, σ c is static tensile strength, τ c is the incubation time associated with the dynamics of a relaxation process preparing the break. Experimental data on samples 1 and 2, printed on a 3D printer, and the experimental data of raw material from paper Yin and Wang (2010) are shown in the fig.2. In this case, the change in the dimensions of the sample did not significantly change the strength, but only made it possible to study the material at high strain rates. A good agreement between the experimental data and the theoretical curve constructed using the incubation time criterion (1) was obtained. Parameters of theoretical curve E = 1700 GPa, τ c = 57 µ s , σ c = 36 . 5 MPa are determined. 3. Results and discussion