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为准确地测定超高强度钢板材表面裂纹断裂韧性K_1e值,本文提出用开始失稳断裂时的临界载荷Pc代替目前国内外流行的Pmax法计算K_1e、并用声发射技术监测了断裂试验全过程。根据记录的声发射特性从P-V曲线上确定Pc值。用表面裂纹R曲线法作验证,两种方法所得结果符合很好。本文还导出了计算P-V曲线初始切线斜率下降量的经验公式:△V/V=H/7.6(σ/σ_(o2)~2(M/φ)~2利用该式确定“条件载荷”P_o可简化试验方法。
In order to accurately determine the fracture toughness K_1e of super-strength steel sheet, this paper proposes to calculate K_1e by using the critical load Pc at the beginning of instability fracture instead of the current Pmax method at home and abroad. The whole process of fracture test is monitored by acoustic emission technique. The Pc value was determined from the P-V curve based on the recorded acoustic emission characteristics. Surface crack R curve method for verification, the results obtained by the two methods in good agreement. In this paper, an empirical formula for calculating the slope of the initial tangent of the PV curve is also derived: ΔV / V = H / 7.6 (σ / σ_ (o2) ~ 2 (M / φ) Simplify the test method.