CST方式搬送波型動ひずみ測定器の広測定帯域化の解析と実証

摘要

Carrier type dynamic strain amplifiers are frequently used for stress measurement with strain gages. That is because the carrier type dynamic strain amplifier can conduct high precision measurement since it is highly resistant against hum noise from the power supply frequency in principle and is free from the thermoelectomotive force even if a metal contact is used in wiring to a Wheatstone bridge for measuring.rnA problem of the carrier type dynamic strain amplifier is generation of Capacitive component (hereinafter referred to as the C component) in an input cable connecting from the amplifier to the input sensor (Wheatstone bridge for measuring). The C component varies with cable length, cable materials, or ambient temperature change. The aforementioned changing adversely affects the stability of the amplifier. In this paper, we realize and analyze the method that increases the stability of amplifier by detecting, eliminating and self tracking the above C component constantly. Used carrier frequency at 12kHz and 28kHz.rnWe made amplifiers with noise resistant and wide band frequency of measurement range and verified the theory of the Capacitance Self Tracing with the above amplifiers.%構造物に使用される鋼材や，軽量化を図る航空機や自動 車などの構造部材にかかる応力を測定し，適切な形状や使 用量を求めるためには，これらの動的な応力測定が必要で ある。この測定には通常，小型軽量で，測定対象物にほと んど影響しないひずみゲージを直接部材に貼り，動ひずみ 測定器と接続する方法が用いられる。この動ひずみ測定器 には，電源などによるハムノイズや外乱ノイズに強く，金 属接点による熱起電力に影響されない搬送波型動ひずみ測 定器がよく使用される。