High fatigue resistant metal sheet and fixing belt and fixing apparatus using the same and evaluation apparatus of metal material fatigue resistance and method thereof

An endless belt shape fixing belt, comprising:

• an endless belt shape metal sheet;
• and
• a releasing layer formed on the outer surface of said metal sheet, wherein said metal sheet satisfies at least one of the following expressions:
• 0.7<IH/IL≦1 (1)0.25<ZL/ZH≦1 (2)0.7<QH/QL≦1 (3)
• when a first alternating voltage is applied and when a second alternating voltage having the same effective voltage value as the effective voltage value of the first alternating voltage and having higher frequency than the frequency of the first alternating voltage is applied, wherein respectively
• IL represent an effective value of current density when the first alternating voltage is applied;
• IH, an effective value of current density when the second alternating voltage is applied;
• ZL, an impedance when the first alternating voltage is applied;
• ZH, an impedance when the second alternating voltage is applied;
• QL, a calorific power when the first alternating voltage is applied;
• and
• QH, a calorific power when the second alternating voltage is applied.

An fixing apparatus comprising:

• a first roller;
• a second roller;
• a fixing belt including an endless belt shape metal sheet and a releasing layer formed on the outer surface thereof and that is wound around the first roller and the second roller;
• and
• a third roller disposed in a way to be pressed against the first roller via the fixing belt, wherein the metal sheet satisfies at least one of the following expressions:
• 0.7<IH/IL≦1 (1)0.25<ZL/ZH≦1 (2)0.7<QH/QL≦1 (3)
• when a first alternating voltage is applied and when a second alternating voltage having the same effective voltage value as the effective voltage value of the first alternating voltage and having higher frequency than the frequency of the first alternating voltage is applied, wherein respectively
• IL represent an effective value of current density when the first alternating voltage is applied;
• IH, an effective value of current density when the second alternating voltage is applied;
• ZL, an impedance when the first alternating voltage is applied;
• ZH, an impedance when the second alternating voltage is applied;
• QL, a calorific power when the first alternating voltage is applied;
• and
• QH, a calorific power when the second alternating voltage is applied.

An evaluation apparatus of metal material fatigue resistance, comprising:

• a high frequency power source for applying an alternating voltage to a test piece;
• a current measuring instrument for measuring current through a test piece;
• and
• a controller for calculating a ratio of currents through a test piece when a plurality of alternating voltages of the same effective voltage value and different in frequency are applied to a test piece from the high frequency power source, and evaluating fatigue resistance of a test piece based on calculation results thereof.

An evaluation apparatus of metal material fatigue resistance, comprising:

• a high frequency power source for applying an alternating voltage to a test piece;
• a calorific power measuring instrument for measuring a calorific power of each point of a test piece;
• and
• a controller for comparing calorific powers of the same point of a test piece when a plurality of alternating voltages of the same effective voltage value and different in frequency are applied to the test piece from the high frequency power source, and evaluating fatigue resistance of a test piece based on the comparison results thereof.

An evaluation method of metal material fatigue resistance, comprising the steps of:

• applying a plurality of alternating voltages of the same effective voltage value and different in frequency to a test piece and measuring currents through the test piece when each alternating voltage is applied;
• calculating a ratio of measured currents;
• and
• evaluating fatigue resistance of the test piece based on calculation results thereof.

An evaluation method of metal material fatigue resistance, comprising the steps of:

• applying a plurality of alternating voltages of the same effective voltage value and different in frequency to a test piece and measuring calorific powers of the same point of the test piece when each alternating voltage is applied;
• comparing the measured calorific powers;
• and
• evaluating fatigue resistance of the test piece based on the comparison results.