Prediksi Kurva P-h dan Nilai Kekerasan pada Indentasi Bulat Berbasis Pendekatan Tegangan Representatif (?r)

Abstract

Abstrak:

Dalam penelitian ini model elemen hingga untuk indentasi bulat (Spherical) telah dikembangkan dan divalidasi. Sebuahpendekatan untuk memprediksi kurva P-h dari sifat material konstitutif telah dikembangkan dan diuji berdasarkanhubungan antara kelengkungan dan sifat-sifat material dan stres representatif (?r) Hubungan antara parameterkonstitutif material (di tetapkan sebagai yield stress (?y) dan koefisien pengerasan regang (n)) bahan elastis-plastik,kurva P-h (kurva tegangan-kedalaman indentasi) dan kekerasan (hardness) pada indentasi bulat telah diselidiki secarasistematis dengan menggabungkan analisis tegangan representatif dan pemodelan elemen hingga (Finite Elemen)menggunakan baja. Parametrik Finite elemen model indentasi bulat (Spherical) telah dikembangkan sebagai rangesimulasi. Dua pendekatan baru untuk mengkarakterisasi kurva P-h untuk indentasi bulat (Spherical) telahdikembangkan dan dievaluasi. Melalui pendekatan fitting kurva penuh dan pendekatan kedalaman indentasi(indentation depth). Kedua pendekatan tersebut terbukti memadai/efektif dalam memprediksi kurva P-h indentasibahan. Konsep dan metodologi yang dikembangkan kemudian digunakan untuk memprediksi nilai kekerasan (HRB)Rockwell B hardness melalui analisis langsung dan divalidasi dengan data eksperimen pada sampel yang dipilih daribajaKata kunci: Indentasi Bulat, stres representatif, koefisien pengerasan regang, Kurva P-h, HRB

Abstract:

In this work, the finite element model of spherical indentation has been developed and validated. An approach to predictthe P-h curve of the material constitutive properties have been developed and evaluated based on the relationshipsbetween curvature and material properties and representative stress (?r). The relationships between constitutiveparameters of the material (in the set as the yield stress (?y) and strain hardening coefficient (n) ) of elastic-plasticmaterial, P-h curve (Force-indentation depth curve) and hardness in the spherical indentation has been investigatedsystematically by combining the representative stress analysis and finite element modeling using steel. ParametricFinite element model of spherical indentation has developed a range of simulation. Two new approaches to characterizethe P-h curve for spherical indentation has been developed and evaluated. One is the full curve fitting approach whilethe other is depth indentation base approach. Both approaches proved to be adequate / effective in predicting theindentation P-h curve material. The Concepts and methodology developed is to be used to predict the value of hardness(HRB) Rockwell B hardness through direct analysis and validated with experimental data on selected samples of steel.Keywords: Spherical Indentation, representative stress, strain hardening coeff., P-h curve, HRB