基于BS7910《金属结构缺陷可接受性评定方法指南》标准的高强钢焊接接头CTOD(crack tip opening displacement)值的评定方法可以有效克服各国规范CTOD允许值的差异,但是评定结果的保守度一直被关注.文中通过高强钢E47的CTOD试验测试数据...基于BS7910《金属结构缺陷可接受性评定方法指南》标准的高强钢焊接接头CTOD(crack tip opening displacement)值的评定方法可以有效克服各国规范CTOD允许值的差异,但是评定结果的保守度一直被关注.文中通过高强钢E47的CTOD试验测试数据,以有限元模拟辅助手段通过δ5法模拟得到裂纹尖端的真实应力.基于BS7910中的2A级评定方法,对失效评定曲线评估点的横坐标即载荷比进行修正.结果表明:修正后横坐标值小于1,评估点在失效评定曲线安全范围内,且修正后的评估点位置偏于安全.由临界韧度比确定的CTOD允许值δmin较修正前有明显降低,使基于失效评定曲线求CTOD允许值方法更为精确.展开更多
根据多连杆压力机的行程曲线特点,提出了以80%公称力作为公称力控制线,并据此绘制压力机载荷许用区间图,即将力-行程曲线划分为安全区、临界区和危险区。当成形力处于公称力控制线下方,则设备载荷能够满足成形要求;当成形力处于公称力...根据多连杆压力机的行程曲线特点,提出了以80%公称力作为公称力控制线,并据此绘制压力机载荷许用区间图,即将力-行程曲线划分为安全区、临界区和危险区。当成形力处于公称力控制线下方,则设备载荷能够满足成形要求;当成形力处于公称力控制线和公称力曲线之间的临界区,需要进一步对变形功进行校核。另一方面,采用数值积分的方法对成形力和作用距离进行积分,得到变形功,与压力机许用变形功进行比较,提出能量校核的前提和校核方法。最后提出了成形力和变形功校核流程图,并用于前门内板等零件的分析。结果表明,采用22500 k N压力机满足前门内板一模双件载荷要求。展开更多
This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable cond...This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.展开更多
文摘基于BS7910《金属结构缺陷可接受性评定方法指南》标准的高强钢焊接接头CTOD(crack tip opening displacement)值的评定方法可以有效克服各国规范CTOD允许值的差异,但是评定结果的保守度一直被关注.文中通过高强钢E47的CTOD试验测试数据,以有限元模拟辅助手段通过δ5法模拟得到裂纹尖端的真实应力.基于BS7910中的2A级评定方法,对失效评定曲线评估点的横坐标即载荷比进行修正.结果表明:修正后横坐标值小于1,评估点在失效评定曲线安全范围内,且修正后的评估点位置偏于安全.由临界韧度比确定的CTOD允许值δmin较修正前有明显降低,使基于失效评定曲线求CTOD允许值方法更为精确.
文摘根据多连杆压力机的行程曲线特点,提出了以80%公称力作为公称力控制线,并据此绘制压力机载荷许用区间图,即将力-行程曲线划分为安全区、临界区和危险区。当成形力处于公称力控制线下方,则设备载荷能够满足成形要求;当成形力处于公称力控制线和公称力曲线之间的临界区,需要进一步对变形功进行校核。另一方面,采用数值积分的方法对成形力和作用距离进行积分,得到变形功,与压力机许用变形功进行比较,提出能量校核的前提和校核方法。最后提出了成形力和变形功校核流程图,并用于前门内板等零件的分析。结果表明,采用22500 k N压力机满足前门内板一模双件载荷要求。
文摘This paper considers the influence of changes of the transmission lines of permissible load current depending on conductor and ambient temperatures, climate conditions. The theoretical background of the allowable conductor temperature as well as load current determination principles are proposed. On one hand, the principles are based on mechanical limitations; on the other hand, they are based on thermal limitations. The simulation tasks were based on specific data information of three existing overhead lines of Latvian power system as well as the planned 330 kV overhead line. Moreover, the special thermovision device was used for precious determination of conductor temperature of the existing transmission lines. The simulation results of the obtained data are reviewed in the paper.
