Material Properties of HY 80 Steel after 55 Years of Operation for FEM Applications

The paper presents the results of testing the properties of HY 80 steel from the hull of a Kobben class 207 submarine after 60 years of operation in extreme sea conditions. Steels from the HY family in the post-war period were used to build American and German submarines. For the obtained fragment of steel from the hull of the Polish submarine ORP Jastrząb (ORP-Boat of the Republic of Poland), static tensile tests were performed on an MTS testing machine. Dynamic tensile tests were carried out on a rotary hammer for the strain rate in the range of 500–2000 s−1. Results: Based on the obtained results, the Johnson–Cook model and the failure parameters of HY 80 steel in terms of the finite element method (FEM) were developed. Conclusion: This model can be used to simulate fast-changing processes such as resistance of structures to collisions, shelling, and the impact of pressure waves caused by explosions in water and air related to submarines.

Determination of Dynamic Characteristics of Austenitic Steel to be Utilized in Fem Simulation and its Verification

This paper presents the dynamic mechanical properties of austenitic steel with improved durability, which is used in the construction of hulls of minesweepers, mine destroyers, submarines and other naval vessels. Dynamic tensile tests performed on the steel samples using a rotary hammer with a strain rate of up to 1000 s-1 allowed determination of elastic-plastic characteristics of the material in the form of a polynomial of Johnson-Cook constitutive model, taking into account the influence of strain rate and temperature. A characteristic of this type is utilized in numerical calculations in the CAE software. The obtained characteristics were experimentally verified by bending tests of flat samples with a drop-weight type impact hammer. Simultaneously numerical calculations were performed in order to compare the deformation state.

Effects of Additives on Tensile Properties of Polyhydroxyalkanoate/Polycaprolactone Polymer Blends

Bioplastics have attracted attention over the years from a perspective of environmental protection. Recently, attention is focused on bioplastics derived from inedible objects. Polyhydroxyalkanoates (PHAs) are known as a microbial origin plastic and expected to deal effectively with the food security issue. In this study, in order to use PHA for industrial and machinery parts and products, polycaprolactone (PCL) was blended with a PHA-based pellet to improve ductility and tensile strength. The effects of additives on tensile strength and elongation at break, dynamic tensile tests of the polymer blends were examined using split Hopkinson bar (SHPB) method at high strain rates.

UJI TARIK DINAMIS BATANG SAMPEL ALUMINUM 6061T8 DENGAN METODA FOTOGRAFIS = DYNAMIC TEST PULL ROD 6061T8 ALUMINUM SAMPLES WITH PHOTOGRAPHICALLY METHODS

The model system of a photographic using light-emiting dioda (LED) iluminator and a 35-mm rotating drum camera has ben developed for diagnosis of dynamic-tensile tests conducted with split tension bar. Back-lit photographs of deforming tensile samples are obtained at rates up to 50 kHz that test were conducted with 6061T8 aluminum, since this material is relatively well characterized and relatively insentive to strain rate and work hardening. The LED exposures are precisely time corrected with the conventional bar-straingage records. The system can be used to extended the measurement of stressstrain-gage curves beyond the onset of plastic instability. ABSTRAKSistem pemodelan fotografis yang menggunakan iluminator LED (Light Emiting Dioda) dan kamera film 35 mm di coba untuk digunakan mendiagnosis uji tarik dinamis batang uji. Pengulangan pada uji fotografis pada beberapa bentuk sampel uji tarik aluminum 6061T8 dengan kecepatan sampai dengan 50 kHz , yang mana material ini relatif memiliki karakteristik yang sangat bagus dan relatif lebih tahan terhadap kekuatan regangan rata-ratamya dan tingkat kekerasan yang tinggi. Pencahayaan LED pada saat yang tepat dapat terkoreksi hasilnya dengan pencatatan pengukuran batang sampel uji konvensional. Pemakaian ini dapat dipergunakan lebih luas untuk pengukuran kurva tegangan-regangan terhadap deformasi plastis yang labil.

The Research of Strain Rate of Common Bolt Materials

In this article, quasi-static tensile and dynamic tensile tests of three common bolt materials (three kinds of steels) were conducted, and their stress-strain curves at various strain rates were obtained. By this means, the mechanical properties of three common bolt materials were analyzed. Based on the John-Cook model, author established the constitutive relation models of three materials which could describe their strain rate dependence, and used these models in the numerical simulation. The research show us that bolt material strain rate effect not only could affect the bolt impact strength, but also could not be ignored in the study of impact strength of equipments connected by bolts. The research has great significance to the study of impact resistance strength of equipments and bolts.