JP3882081B2

JP3882081B2 - Damage detection method for shape memory alloy, self-sensing heating control method, and panel self-repair method

Info

Publication number: JP3882081B2
Application number: JP2003129758A
Authority: JP
Inventors: 龍男杉山; 淑雄秋宗; 一雄松尾; 一郎萩原; 泰裕毛利
Original assignee: National Institute of Advanced Industrial Science and Technology AIST
Current assignee: National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2003-05-08
Filing date: 2003-05-08
Publication date: 2007-02-14
Anticipated expiration: 2023-05-08
Also published as: JP2004333306A

Description

【０００１】
【発明の属する技術分野】
この発明は、ＳＭＡ線の抵抗変化を測定し抵抗の時間微分値より、損傷位置を検出し、ＳＭＡ線に通電加熱制御を行うことにより、マルテンサイト相からオーステナイト相への変態を検知制御することよって損傷拡大を防止するものであり、具体的には形状記憶合金の損傷位置検出方法、自己感知型加熱制御法及び自己修復方法並びに複合材料製パネル及び絶縁皮膜で覆った形状記憶合金に関する。
【０００２】
【従来の技術】
ＳＭＡ（形状記憶合金）の特異な物性値、強い力／重量比、加熱制御が簡単などの利便性により、多くの分野（機械、電気、自動車工学、宇宙航空工業、医療機器等）で多くの利用法が見出されつつあり、特に近年ＳＭＡをセンサーやアクチュエータとして埋め込んだスマートマテリアルが注目を集めている。
その理由は、スマートマテリアルは簡単な制御により、能動的な観測装置として利用できたり、また、環境に応じて自らを適合させたりできるからである。このような点から、構造物の自己補修、能動制振、騒音制御、ロボットの部品等への利用法が多数報告されている。
【０００３】
従来、ＳＭＡを用いた損傷検出方法として、複合材料内に埋設したＳＭＡの抵抗を測定し電気抵抗の変化から損傷を検知する方法が提案されている（特許文献１参照）。この方法では複合材パネル周囲の環境、特に温度の変化により抵抗値が変化するため損傷を検知の精度が悪く、パネルに損傷が生じたことは解っても発生した位置が不明であるという問題がある。
また、形状記憶合金部材の多数回の繰返し熱サイクル試験を行う場合に、これを短期間で簡単に行う方法として、形状記憶合金部材を通電加熱する方法が提案されている。この場合、抵抗値を測定することによって変形量を判別しようとするものである（特許文献２参照）。
【０００４】
通常、ＳＭＡの変態は自己通電加熱(以下、加熱)により引き起こさせる。この場合、ＳＭＡは限界温度を超えて加熱され、マルテンサイト相からオーステナイト相へと変態する。このとき、最初に与えられていた非弾性歪が除かれて、より高い温度で設定されていた元の形状に戻る。
ＳＭＡを構造物の自己修復のような用途で使用する場合は、出来るだけ早く変態を起こさせる必要があり、そのためには大電流を流さなければならない。
しかし、大電流を流すと過加熱が生じ、形状記憶能力が失われたり、異常な変形やＳＭＡの剥離が生じたり、ひどい場合には、周りが燃えたりするかもしれない。特に周囲温度や対流、放射熱の状態が不明な場合、定められた加熱電流で正確な加熱時間を決めることはきわめて困難である。
【０００５】
【特許文献１】
特開平８−１５２０８号公報
【特許文献２】
特開２００１−９９７７０号公報
【０００６】
【発明が解決しようとする課題】
本発明は、絶縁皮膜で覆ったＳＭＡ線を、複合材料内に格子状に埋設したパネルにおいて、パネルの損傷位置及び方向を、ＳＭＡ線の抵抗を随時測定し抵抗の時間微分をもとめ損傷位置等の判定を行い、損傷を検知したＳＭＡ線にパルス電流を流しＳＭＡ線の加熱を行うと共に抵抗測定を行い、抵抗の時間微分からパルス電流を遮断することで周囲温度等の影響を受けることなく加熱電流や加熱時間の適正化を図り、高速かつ過加熱することなく損傷の進展を阻止することができる形状記憶合金の損傷位置検出方法、自己感知型加熱制御法及び自己修復方法並びに複合材料製パネル及び絶縁皮膜で覆った形状記憶合金を提供することを課題とする。
【０００７】
【課題を解決するための手段】
本発明は、ＳＭＡ線の抵抗変化を測定し抵抗の時間微分値より、損傷位置及び方向を検出し、ＳＭＡ線に通電加熱制御を行うことにより、マルテンサイト相からオーステナイト相への変態を検知・制御することができ、さらに損傷拡大を防止できるとの知見を得た。
本発明は、この知見に基づいて、
１．複合材料内に、交差する絶縁皮膜で覆った形状記憶合金(以下、ＳＭＡ) 線を格子状に埋設したパネルにおいて、パネルの損傷位置を、ＳＭＡ線の抵抗を随時測定し抵抗の時間微分をもとめ時間微分許容限度を、抵抗の時間微分値の０．９％の以内とすることにより損傷位置の判定を行うことを特徴とするパネル中の形状記憶合金の損傷位置検出方法。
２．損傷位置検出過程でＳＭＡ線の抵抗変化を測定し、比抵抗の時間微分を計算で求め、時間微分許容限度よりＳＭＡの菱面体相(以下、R相)の有無にかかわらず、スマート複合材料の損傷位置を確認することを特徴とする上記１記載のパネル中の形状記憶合金の損傷位置検出方法。
３．複合材料内に、交差する絶縁皮膜で覆ったＳＭＡ線を格子状に埋設したパネルにおいて、パネルの損傷位置を、ＳＭＡ線の抵抗を随時測定し抵抗の時間微分をもとめ時間微分許容限度より損傷位置等の判定を行い、損傷を検知したＳＭＡ線に、パルス電流を流しＳＭＡ線の加熱を行い、損傷の修復を行うことを特徴とするパネルの自己修復方法。
４．損傷位置検出過程でＳＭＡ線の抵抗変化を測定し、比抵抗の時間微分を計算で求め、時間微分許容限度よりＳＭＡのＲ相の有無にかかわらず、スマート複合材料の損傷位置を確認することを特徴とする上記３記載のパネルの自己修復方法。
５．複合材料内に、交差する絶縁皮膜で覆ったＳＭＡ線を格子状に埋設したパネルにおいて、パネルの損傷位置を、ＳＭＡ線の抵抗を随時測定し抵抗の時間微分をもとめ時間微分許容限度より損傷位置等の判定を行い、損傷を検知したＳＭＡ線にパルス電流を流してＳＭＡ線の高速加熱を行い、かつ同時に抵抗測定を行い、比抵抗の時間微分をもとめ、R相の有無にかかわらず、ＳＭＡ線の変態開始・終了を判定することを特徴とするパネル中の形状記憶合金の自己感知型加熱制御法。
６．複合材料内に、交差する絶縁皮膜で覆ったＳＭＡ線を格子状に埋設したパネルにおいて、パネルの損傷位置を、ＳＭＡ線の抵抗を随時測定し抵抗の時間微分をもとめ時間微分許容限度より損傷位置等の判定を行い、損傷を検知したＳＭＡ線にパルス電流を流してＳＭＡ線の高速加熱を行い、かつ同時に抵抗測定を行い、比抵抗の時間微分をもとめ時間微分規定値の範囲に入った時にパルス電流を遮断することにより過加熱することなく損傷の加熱による修復を終了させることを特徴とするパネルの自己修復方法。
７．ＳＭＡ線の加熱を行うと共に同時に抵抗測定を行い、比抵抗の時間微分をもとめ、ＳＭＡのR相の有無にかかわらず、ＳＭＡの変態開始・終了を判定することを特徴とする上記６記載のパネルの自己修復方法。
を提供する。
【０００８】
さらに本発明は、
８．加熱過程でＳＭＡ線にパルス電流を流し、ＳＭＡ線の加熱及び抵抗測定を行い、抵抗の時間微分値が時間微分規定値を超えた時にパルス電流を遮断することを特徴とする上記３〜７のいずれかに記載のパネル中の形状記憶合金の自己感知型加熱制御法又はパネルの自己修復方法。
９．抵抗の時間微分許容限度は、比抵抗の時間微分値をもとめ、その値の０．９％の以内とすることを特徴とする上記１〜８のいずれかに記載のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法。
１０．抵抗の時間微分許容限度は、比抵抗の時間微分値をもとめ、その値の０．５％以内とすることを特徴とする上記９に記載の形状記憶合金のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法。
１１．抵抗の時間微分規定値は、比抵抗の時間微分値をもとめ、その値の±６０％の範囲とすることを特徴とする上記６〜１０のいずれかに記載のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法。
１２．抵抗の時間微分規定値は、比抵抗の時間微分値をもとめ、その値の±３０％の範囲とすることを特徴とする上記６〜１０のいずれかに記載のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法。
１３．複合材料製パネルが、カーボン繊維系複合材料又はガラス繊維系材料を成型したことを特徴とする上記１〜１２のいずれかに記載のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法に使用する複合材料製パネル。
１４．絶縁皮膜が、熱可塑性樹脂からなるポリイミド・ポリエーテルイミド・弗素樹脂であることを特徴とする上記１〜１３のいずれかに記載のパネル中の形状記憶合金の損傷位置検出方法、パネル中の形状記憶合金の自己感知型加熱制御法及びパネルの自己修復方法。
を提供する。
【０００９】
【発明の実施の形態】
従来、ＳＭＡの損傷検出、加熱制御は、単独で行っている、これは簡便な方法ではあるが、ＳＭＡ材料を有効に利用しているとは言えない。
図１に、ＳＭＡ線２を埋め込んだスマートマテリアル、複合パネル１の模式図を示す。直交する２組のＳＭＡ線２は、互いに接触しないように配置され、ＳＭＡ線２と複合パネル１は糊で固着されている。図１のスマートマテリアルのパネル表面に亀裂が入った場合、すなわち図２（ａ）に示すようにＳＭＡ線を埋め込んだパネルに亀裂３が入った場合、亀裂３の近傍のＳＭＡ線２を早急に加熱収縮させて亀裂３の進展を阻止 (自己補修)するためにＳＭＡ線に大電流を流さなければならない。
そのため、損傷位置を正確に把握しないと、損傷近傍のSMA線２を加熱収縮させることができない。また、加熱電流や加熱時間を余分に設定していると、ＳＭＡ線に過加熱が生じ、形状記憶能力が失われたり、異常な変形やＳＭＡ線の剥離が生じたり、また、火災が生じる可能性もある。
【００１０】
一般にSMA線の周囲温度や対流、放射熱の状態が不明な場合が多いので、定められた加熱電流で正確な加熱時間を決めることはきわめて困難である。
そこで、損傷位置を正確に把握しＳＭＡ線の高速加熱により、しかも過加熱することなく、早急に変態を起こし終了させる加熱制御法が必要である。
ＳＭＡはその金属相により、ヤング率、減衰、比熱、などの多くの物性値が異なる。その構造上の特徴により、ＳＭＡの抵抗値はマルテンサイト相からオーステナイト相へと変わるとき、これら２つの相の体積比に大きく依存する。
そこで、ＳＭＡの抵抗値を測定すればその体積比、すなわち、変態の過程を知ることができる。図２の（ｂ）は、本発明によりＥＷ２とＮＳ３のＳＭＡ線を加熱し収縮させ、ＳＭＡ線の相変態により亀裂の幅が狭まった様子を示す。
しかし、その抵抗値は温度に依存するだけでなく、熱処理によっても変わり、さらに、変態の繰り返しが多くなるとその抵抗値は変化していく。
【００１１】
一例として、Ｔｉ−Ｎｉ合金の代表的な温度−比抵抗特性を図３に示す。このような変化は、ＳＭＡに加わる応力変化によっても生じる。
また、図３を見ると、比抵抗の変化は、マルテンサイト相に介在するＲ相の存在する場合は存在しない場合より大きいことが分かる。Ｒ相の有無はその熱処理に依存し、Ｒ相が存在すると、変態の繰り返しが多くなるに従い、比抵抗の再現性が悪くなり、抵抗値は温度により一様に変化しなくなる。
しかし、図３から分かるように、Ｒ相の有無にかかわらず、変態の始まりと終わりに明確な変曲点が存在する。
ＳＭＡの変態の開始と終了を求めるための時間に対する比抵抗の時間微分の計算値と実測値とを図４に示す。比抵抗の時間微分は変態の開始と終了の間で比抵抗の時間微分は最小値から最大値へと変化し、再び最小値へと変化する。
【００１２】
一方、図５に示すように、加熱を続けたときの比抵抗の変化はその時間微分に比べさほど明確でないため、比抵抗の時間微分を使用する方が、制御に対し有効であり、抵抗変化は、温度に対する微分を見るのではなく、比抵抗の時間に対する微分を求めることで周囲環境の変動を除外することができ、変態開始と終了に対応する抵抗変化値を明確に検出できることから、その開始と終了を予測する制御方法と制御回路を創案した。
【００１３】
格子状に埋設したＳＭＡ線の抵抗値を順次測定し、比抵抗の時間微分値を計算する。外部から応力を受けることでＳＭＡ線は比抵抗の時間微分値が大きく変化する。
そこで、ＳＭＡ線の時間微分値の挙動をモニターし、埋設したＳＭＡ線個々の時間微分値を比較し、応力を受けたＳＭＡ線を判定することで、損傷位置を精度良く検知することができる。
比抵抗の時間微分値が大きく変化したＳＭＡ線に加熱電流を流しながら抵抗値を測定し、比抵抗の時間微分値を計算し、その値が増加し始めると変曲点を通過し変態が始まり、減少し安定すると変態が終了したと判定し加熱電流を遮断することで自己修復を完了させる方法である。
これにより、周囲温度等の影響を受けることなく損傷位置を判定し加熱電流や加熱時間の適正化が図られ、ＳＭＡの変態を適切に行うことができ、損傷の進展を阻止することができる。また、過加熱を抑止することができ、形状記憶能力の消失、異常な変形、剥離を抑制することができ、また、火災の防止になる
【００１４】
次に、本発明の実施例を説明する。なお、これらの実施例等は本発明とその効果を容易に理解できるようにするための説明であり、本発明はこれらの説明に限定されるものではない。したがって、本発明の技術思想に基づく変形、態様、及び他の実施例等はいずれも本発明に包含されるものである。
【００１５】
（実施例）
熱可塑性樹脂からなるポリイミド・ポリエーテルイミド・弗素樹脂を用いた絶縁皮膜で覆った形状記憶合金を、カーボン繊維系複合材料やガラス繊維系材料に格子状に埋設したパネルを用い損傷の自己修復実験を行った。
図６に、複合材料パネル１に予亀裂４を入れ、引張り荷重を加え、亀裂４を進展させ、自己修復システムで損傷位置、方向を検知し、加熱制御を行い自己修復の確認を行った実験の概略図を示す。
図７は本実施例の制御回路５の概略図である。
【００１６】
実験の概略手順は
１．デジタル I/Oの指令によりＳＷを開にし、スキャナでＳＭＡ線を次々に選択しながら、ＳＭＡ線に流れる電流値を A/D 変換機で読みとり、これより、比抵抗の時間微分値を計算する。
２．直交する2本のＳＭＡ線において比抵抗の時間微分値が設定した許容限度を超えていれば、その直交点に損傷が発生していることになる。この場合は手順3.にいく。超えていなければ、手順1.に戻る。
３．直交点(この座標を(x,y)とする)の周り(x-1〜x+1,y-1〜y+1)に対応するＳＭＡ線の比抵抗の時間微分値を比較すると、その大小により損傷の大きい方向が分かるので、損傷の大きい方のＳＭＡ線と(x,y)に対応するＳＭＡ線について、加熱制御処置を施こす。
このとき、ＳＷを閉じることで加熱電流が流れる。なお、そのＳＭＡの変態がすでに終了していれば、その隣を加熱する。変態終了後、手順１．へ戻る。
【００１７】
すなわち、ＳＭＡ線の電圧ＶｔｓｔとＶｓｍｐをＡ／Ｄ変換器を通してパソコンに取り込みＲｓとＶｔｓｔ、ＶｓｍｐからＳＭＡ線の抵抗値を測定し、比抵抗の時間微分を計算して、時間微分値の挙動をモニターを行い時間微分許容限度値と比較することで、損傷位置、方向の判定を行いながら、加熱制御を行うＳＭＡ線を決定し、決定したＳＭＡ線の加熱・抵抗値測定を行い比抵抗の時間微分を計算して、時間微分規定値に達するまでＳＭＡ線の加熱抵抗感知を繰り返すことにより自己修復を行う手順で実施した。
【００１８】
図８は、複合材料パネル５の予亀裂４から亀裂が進展することにより、ＳＭＡ線が応力変動を受け、比抵抗の時間微分値が大きく変化する挙動をモニターした結果を示す例である。
時間微分許容限度値を０．５％に設定し、格子状に埋設したＳＭＡ線の抵抗値を順次測定を行い、比抵抗の時間微分値の計算を行い時間微分値の挙動をモニターし埋設した個々のＳＭＡ線を時間微分許容限度値と比較することで微小な損傷の位置、方向を検知することができた。
時間微分許容限度値が０．６〜０．９％では損傷が拡大するが損傷の位置より認知しやすくなる。
【００１９】
また、時間微分限度値が１％以上になると複合材料パネル亀裂が進展し破断してしまう。時間微分規定値を±３０％の範囲に設定し、格子状に埋設したＳＭＡ線の抵抗値を順次測定を行い、比抵抗の時間微分値の計算を行い時間微分値の挙動をモニターし埋設した個々のＳＭＡ線を比較することで正確に損傷位置を検知することができ、複合材料パネルの損傷部位のＳＭＡ線に加熱電流を流し過加熱することなく加熱制御を行うことができ損傷の進展を阻止した。
【００２０】
しかし、時間微分規定値を−４０〜−６０％の範囲においては、若干の過加熱が見られ、＋７０％以上では、変態が未完了の状態で自己修復が不完全であり、−７０％以上では、形状記憶能力の消失、異常な変形、剥離に至る過加熱であった。
加熱制御の通電加熱電流を変えたときの変態終了時間の関係を図９に示す。通電加熱電流が大きいと変態終了時間が早くなり、この例のＳＭＡ変態終了温度である６２°Ｃを超えると自動的に加熱電流が遮断制御され自己修復が完了した。
実験では、加熱期間は０．１秒としたが、変態終了時間を短縮したい場合は、加熱電流を多くし、加熱時間は精度に応じて決めると良い。
このように、加熱電流や加熱時間を自由に選べることが、本方法の有効性を示す点の一つである。
【００２１】
【発明の効果】
本発明は、絶縁皮膜で覆ったＳＭＡ線を、複合材料内に格子状に埋設したパネルにおいて、パネルの損傷位置をＳＭＡ線の抵抗を随時測定し、抵抗の時間微分をもとめて損傷位置等の判定を行い、損傷を検知したＳＭＡ線にパルス電流を流し、ＳＭＡ線の加熱及び抵抗測定を行い、抵抗の時間微分からパルス電流を遮断することによって、周囲温度等の影響を受けることなく加熱電流や加熱時間の適正化を図ることができる著しい効果を有する。
また、本発明によって、高速かつ過加熱することなく損傷の進展を阻止することができる。そして、このため形状記憶能力の消失、異常な変形、剥離を抑制することができ、また、火災の防止になるという優れた効果を有する。
さらに、本発明の制御方法と制御回路を用いると、周囲温度や対流、放射熱の状態が不明な場合でもＳＭＡの相変態の状態を自動検知することができ、加熱電流や加熱時間はＳＭＡの用途に応じ自由に設定できるので利用域が広く、ＳＭＡを目的に応じて変態させたいスマートマテリァルに対してすべて応用することができる。
【図面の簡単な説明】
【図１】ＳＭＡ線を埋め込んだスマートマテリアル、複合パネルの模式図である。
【図２】ＳＭＡ線を埋め込んだパネルに亀裂が入った場合（ａ）とＥＷ２とＮＳ３のＳＭＡ線を加熱し収縮させ、ＳＭＡ線の相変態により亀裂の幅が狭まった様子（ｂ）を示す模式図である。
【図３】Ｔｉ−Ｎｉ合金の代表的な温度−比抵抗特性を図である。
【図４】比抵抗の時間微分の計算値と実測値とを示す図である。
【図５】比抵抗の時間微分と比抵抗の変化を示す図である。
【図６】複合材料パネルに予亀裂を入れ、引張り荷重を印加し、亀裂を進展させ、自己修復システムで損傷位置を検知し、加熱制御を行い自己修復の確認を行った実験の概略説明図である。
【図７】本実施例の制御回路の概略図である。
【図８】亀裂が生じたときの時間微分のモニター例を示す図である。
【図９】加熱電流を変えたときの変態終了時間を示す図である。
【符号の説明】
１．複合パネル
２．ＳＭＡ線
３．亀裂
４．予亀裂
５．制御回路[0001]
BACKGROUND OF THE INVENTION
The present invention, from the time differential value of the measured change in resistance of SMA wire resistance, to detect the damaged position, by performing the energization heating control to the SMA wire, by detecting control transformation from the martensite phase to the austenite phase Accordingly, the present invention relates to a method for preventing damage expansion, and more specifically, relates to a shape memory alloy damage position detection method, a self-sensitive heating control method and a self-healing method, a composite panel and a shape memory alloy covered with an insulating film.
[0002]
[Prior art]
Due to the unique physical properties of SMA (shape memory alloy), strong force / weight ratio, and convenience such as easy heating control, it can be used in many fields (mechanical, electrical, automotive engineering, aerospace industry, medical equipment, etc.) Use methods are being discovered, and in particular, smart materials in which SMA is embedded as a sensor or actuator have recently attracted attention.
The reason is that the smart material can be used as an active observation device by simple control, and can adapt itself according to the environment. From this point of view, many reports have been made on methods for self-repair of structures, active vibration suppression, noise control, robot parts, and the like.
[0003]
Conventionally, as a damage detection method using SMA, a method has been proposed in which the resistance of an SMA embedded in a composite material is measured to detect damage from a change in electrical resistance (see Patent Document 1). In this method, the resistance value changes due to the environment around the composite panel, especially the temperature, so the accuracy of detecting damage is poor, and even if it is understood that the panel has been damaged, the position where it occurred is unknown. is there.
In addition, as a method for easily performing this in a short time when a large number of repeated thermal cycle tests are performed on the shape memory alloy member, a method of energizing and heating the shape memory alloy member has been proposed. In this case, the amount of deformation is determined by measuring the resistance value (see Patent Document 2).
[0004]
Usually, SMA transformation is caused by self-energized heating (hereinafter referred to as heating). In this case, the SMA is heated above the limit temperature and transforms from the martensite phase to the austenite phase. At this time, the inelastic strain applied first is removed, and the original shape set at a higher temperature is restored.
When SMA is used for applications such as self-healing of structures, it is necessary to cause transformation as soon as possible, and for that purpose a large current must be passed.
However, when a large current is applied, overheating occurs, shape memory ability is lost, abnormal deformation or SMA peeling occurs, and in severe cases, the surroundings may burn. In particular, when the ambient temperature, convection, and radiant heat state are unknown, it is extremely difficult to determine an accurate heating time with a predetermined heating current.
[0005]
[Patent Document 1]
JP-A-8-15208 [Patent Document 2]
JP-A-2001-99770 [0006]
[Problems to be solved by the invention]
The present invention relates to a panel in which an SMA wire covered with an insulating film is embedded in a lattice shape in a composite material, the damage position and direction of the panel, the resistance of the SMA wire is measured at any time, the time differential of the resistance is obtained, the damage position, etc. The SMA wire is heated by applying a pulse current to the SMA wire where the damage is detected, the resistance is measured, and the pulse current is cut off from the time derivative of the resistance, and it is heated without being affected by the ambient temperature. Shape memory alloy damage position detection method, self-sensing heating control method and self-healing method, and composite material panel capable of optimizing current and heating time and preventing damage from progressing at high speed without overheating It is another object of the present invention to provide a shape memory alloy covered with an insulating film.
[0007]
[Means for Solving the Problems]
The present invention is, from the time differential value of the measured change in resistance of SMA wire resistance, to detect the damaged position and orientation, by performing the energization heating control to the SMA wire, - detecting the transformation from the martensite phase to the austenite phase The knowledge that it can control and can prevent damage expansion is obtained.
The present invention is based on this finding.
1. In a composite material, a shape memory alloy (hereinafter referred to as SMA) wire covered with intersecting insulating films is embedded in a grid pattern. The damage position of the panel is measured, and the resistance of the SMA wire is measured as needed to determine the time derivative of the resistance. A damage position detection method for a shape memory alloy in a panel , characterized in that a damage position is determined by setting an allowable time differential limit within 0.9% of a time differential value of resistance .
2. The resistance change of the SMA wire is measured in the process of detecting the damage position, the time derivative of the specific resistance is calculated, and the smart composite material is detected regardless of the presence or absence of the rhombohedral phase (hereinafter R phase) of the SMA from the time derivative tolerance limit. 2. The method for detecting a damage position of a shape memory alloy in the panel according to 1 above, wherein the damage position is confirmed.
3. In a panel in which SMA wires covered with intersecting insulating films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time by measuring the resistance of the SMA wire , and the damage position is determined from the time differential allowable limit. A self-repairing method for a panel, comprising: applying a pulse current to the SMA wire in which damage is detected, heating the SMA wire , and repairing the damage.
4). Measure resistance change of SMA wire during damage position detection process, find time derivative of specific resistance by calculation, and confirm damage position of smart composite material regardless of presence or absence of R phase of SMA from time derivative allowable limit 4. The panel self-repairing method according to 3 above.
5). In a panel in which SMA wires covered with intersecting insulating films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time by measuring the resistance of the SMA wire , and the damage position is determined from the time differential allowable limit. Etc., a pulse current is passed through the SMA wire in which damage is detected, the SMA wire is heated at the same time, and the resistance is measured at the same time to determine the time derivative of the specific resistance, regardless of the presence or absence of the R phase. A self-sensing heating control method for a shape memory alloy in a panel , characterized by determining the start / end of transformation of a wire .
6). In a panel in which SMA wires covered with intersecting insulating films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time by measuring the resistance of the SMA wire , and the damage position is determined from the time differential allowable limit. a determination is equal, performs a fast heating of the SMA wires by supplying a pulse current to the SMA wire is detected damage, and simultaneously performs a resistance measurement, when entering the range of the ratio time differentiation of the determined time derivative specified value of the resistor A panel self-healing method characterized in that the repair by damage heating is terminated without overheating by interrupting the pulse current.
7). 7. The panel as described in 6 above, wherein the SMA wire is heated and the resistance is measured at the same time, the time derivative of the specific resistance is obtained, and the start / end of the SMA transformation is determined regardless of the presence or absence of the R phase of the SMA. self-healing methods.
I will provide a.
[0008]
Furthermore, the present invention provides
8). Flowing a pulse current to the SMA wire in the heating process, subjected to heat and resistance measurements of the SMA wire, the time differential value of the resistance of the 3-7, characterized by interrupting the pulse current when exceeding the time differential prescribed value A self-sensing heating control method for a shape memory alloy in a panel or a method for self-repairing a panel .
9. The tolerance of time differentiation of the resistance is obtained within 0.9% of the value obtained by obtaining the time differentiation value of the specific resistance, and the shape memory alloy in the panel according to any one of the above 1 to 8, wherein Damage position detection method, self-sensing heating control method of shape memory alloy in panel, and self-repair method of panel .
10. 10. The tolerance position of the shape memory alloy in the shape memory alloy panel as described in 9 above, wherein the allowable time differential limit of the resistance is within 0.5% of the value obtained by obtaining the time differential value of the specific resistance. Detection method, self-sensing heating control method of shape memory alloy in panel, and self-repairing method of panel .
11. The time differential prescribed value of the resistance is obtained from the time differential value of the specific resistance, and is within a range of ± 60% of the value . Damage to the shape memory alloy in the panel according to any one of 6 to 10 above A position detection method, a self-sensing heating control method for a shape memory alloy in a panel, and a panel self-repair method.
12 The time differential prescribed value of the resistance is obtained from the time differential value of the specific resistance, and is within a range of ± 30% of the value . Damage to the shape memory alloy in the panel according to any one of the above 6 to 10 A position detection method, a self-sensing heating control method for a shape memory alloy in a panel, and a panel self-repair method.
13. The method for detecting a damage position of a shape memory alloy in a panel according to any one of 1 to 12 above , wherein the composite material panel is formed by molding a carbon fiber-based composite material or a glass fiber-based material , and the shape in the panel A composite panel used in a memory alloy self-sensing heating control method and a panel self-healing method.
14 14. The method for detecting a damage position of a shape memory alloy in a panel according to any one of 1 to 13 above , wherein the insulating film is polyimide, polyetherimide, or fluorine resin made of a thermoplastic resin , and the shape in the panel Self-sensing heating control method for memory alloy and self-healing method for panel .
I will provide a.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Conventionally, damage detection and heating control of SMA are performed independently. This is a simple method, but it cannot be said that SMA material is effectively used.
FIG. 1 shows a schematic diagram of a smart material composite panel 1 in which an SMA wire 2 is embedded. Two sets of SMA wires 2 orthogonal to each other are arranged so as not to contact each other, and the SMA wires 2 and the composite panel 1 are fixed with glue. When a crack is generated on the surface of the smart material panel of FIG. 1, that is, as shown in FIG. 2 (a), when a crack 3 enters a panel embedded with an SMA line, the SMA line 2 near the crack 3 is immediately removed. A large current must be passed through the SMA wire in order to prevent the crack 3 from progressing (self-repair) by heat shrinking.
Therefore, unless the damage position is accurately grasped, the SMA wire 2 in the vicinity of the damage cannot be heated and contracted. Also, if the heating current and heating time are set excessively, the SMA wire may be overheated, resulting in loss of shape memory capability, abnormal deformation, peeling of the SMA wire, or fire. There is also sex.
[0010]
In general, since the ambient temperature, convection, and radiant heat state of the SMA wire are often unknown, it is extremely difficult to determine an accurate heating time with a predetermined heating current.
Therefore, there is a need for a heating control method in which the damage position is accurately grasped, and the transformation is promptly caused to end by rapid heating of the SMA wire and without overheating.
SMA differs in many physical properties such as Young's modulus, attenuation, and specific heat depending on its metal phase. Due to its structural characteristics, the resistance value of SMA greatly depends on the volume ratio of these two phases when changing from the martensite phase to the austenite phase.
Therefore, by measuring the resistance value of SMA, the volume ratio, that is, the transformation process can be known. FIG. 2 (b) shows that the EW2 and NS3 SMA wires are heated and contracted according to the present invention, and the crack width is narrowed by the phase transformation of the SMA wires.
However, the resistance value not only depends on the temperature, but also changes depending on the heat treatment, and further, the resistance value changes as the number of transformations increases.
[0011]
As an example, a typical temperature-specific resistance characteristic of a Ti—Ni alloy is shown in FIG. Such a change is also caused by a change in stress applied to the SMA.
Moreover, when FIG. 3 is seen, it turns out that the change of a specific resistance is larger than the case where it does not exist when the R phase intervening in a martensite phase exists. The presence or absence of the R phase depends on the heat treatment. When the R phase is present, the reproducibility of the specific resistance deteriorates as the number of transformations increases, and the resistance value does not change uniformly with temperature.
However, as can be seen from FIG. 3, there is a clear inflection point at the beginning and end of the transformation regardless of the presence or absence of the R phase.
FIG. 4 shows calculated values and actual measured values of specific resistance with respect to time for determining the start and end of SMA transformation. The time derivative of the specific resistance changes from the minimum value to the maximum value between the start and end of the transformation, and then changes again to the minimum value.
[0012]
On the other hand, as shown in FIG. 5, since the change in specific resistance when heating is continued is not so clear as compared with the time derivative, it is more effective for control to use the time derivative of specific resistance, and the resistance change Rather than looking at the derivative with respect to temperature, it is possible to exclude the fluctuation of the surrounding environment by obtaining the derivative with respect to time of the specific resistance, and it is possible to clearly detect the resistance change value corresponding to the start and end of the transformation. A control method and control circuit to predict the start and end were devised.
[0013]
The resistance value of the SMA wire embedded in the grid is sequentially measured, and the time differential value of the specific resistance is calculated. By receiving stress from the outside, the time differential value of the specific resistance of the SMA wire changes greatly.
Therefore, monitoring the behavior of the time differential value of the SMA wire, and comparing the embedded the SMA wire each time differential value, by determining the SMA wire stressed, it is possible to accurately detect the damage location.
The resistance value is measured while passing a heating current through the SMA wire where the time differential value of the specific resistance has changed significantly, the time differential value of the specific resistance is calculated, and when the value starts to increase, the transformation starts through the inflection point. This is a method in which the self-repair is completed by determining that the transformation has been completed when it decreases and stabilizes, and cutting off the heating current.
Thereby, the damage position is determined without being affected by the ambient temperature and the like, the heating current and the heating time are optimized, the SMA can be appropriately transformed, and the progress of the damage can be prevented. Moreover, overheating can be suppressed, loss of shape memory ability, abnormal deformation and peeling can be suppressed, and fire can be prevented.
Next, examples of the present invention will be described. In addition, these Examples etc. are the description for enabling easy understanding of the present invention and its effects, and the present invention is not limited to these descriptions. Accordingly, all modifications, aspects, and other examples based on the technical idea of the present invention are included in the present invention.
[0015]
(Example)
Self-healing experiment of damage using a panel in which shape memory alloy covered with insulation film using polyimide, polyetherimide, fluorine resin made of thermoplastic resin is embedded in carbon fiber composite material or glass fiber material Went.
Fig. 6 shows an experiment in which a pre-crack 4 was inserted into the composite material panel 1, a tensile load was applied, the crack 4 was propagated, the damage position and direction were detected by a self-healing system, heating control was performed, and self-healing was confirmed. The schematic of is shown.
FIG. 7 is a schematic diagram of the control circuit 5 of this embodiment.
[0016]
The general procedure of the experiment is as follows. The SW in the open by a command from the digital I / O, while selecting the SMA wire one after another in the scanner, the current flowing through the SMA wire is read by the A / D converter, than this, to calculate the time differential value of the resistivity .
2. If the time differential value of the specific resistance exceeds the set allowable limit in the two orthogonal SMA lines , the orthogonal point is damaged. In this case, go to step 3. If not, return to step 1.
3. When the time differential values of the specific resistances of the SMA lines corresponding to (x-1 to x + 1, y-1 to y + 1) around the orthogonal point (the coordinates are (x, y)) are compared, since the direction of larger damage seen by the magnitude, the SMA wire corresponding to the larger of the SMA wire damage (x, y), straining facilities heating control treatment.
At this time, heating current flows by closing SW. If the SMA transformation has already been completed, the adjacent area is heated. After completion of transformation, procedure 1. Return to.
[0017]
That is, the SMA line voltages Vtst and Vsmp are taken into a personal computer through an A / D converter, the resistance value of the SMA line is measured from Rs, Vtst, and Vsmp, the time derivative of the specific resistance is calculated, and the behavior of the time derivative value is calculated. By monitoring and comparing with the time differential permissible limit value, the SMA line for heating control is determined while judging the damage position and direction, the heating and resistance value measurement of the determined SMA line is performed, and the specific resistance time The differential was calculated, and the self-repair was performed by repeating the sensing of the heating resistance of the SMA wire until the time differential specified value was reached.
[0018]
FIG. 8 is an example showing a result of monitoring the behavior in which the SMA wire undergoes stress fluctuation and the time differential value of the specific resistance changes greatly as the crack progresses from the pre-crack 4 of the composite material panel 5.
The time differential allowable limit value was set to 0.5%, the resistance value of the SMA wire embedded in a grid was measured sequentially, the time differential value of specific resistance was calculated, and the behavior of the time differential value was monitored and embedded. The position and direction of minute damage could be detected by comparing each SMA line with the time differential allowable limit value.
When the time differential allowable limit value is 0.6 to 0.9%, the damage is enlarged, but it is easier to recognize than the position of the damage.
[0019]
Further, when the time differential limit value is 1% or more, the composite material panel cracks and breaks. The time differential specified value was set in the range of ± 30%, the resistance value of the SMA wire embedded in a grid was measured sequentially, the time differential value of specific resistance was calculated, and the behavior of the time differential value was monitored and embedded. By comparing the individual SMA wires , the damage position can be detected accurately, and heating control can be performed without overheating by supplying a heating current to the SMA wires at the damaged part of the composite material panel. I stopped it.
[0020]
However, when the time differential specified value is in the range of −40 to −60%, slight overheating is observed, and when it is + 70% or more, transformation is incomplete and self-repair is incomplete, and −70% or more. Then, it was overheating that resulted in loss of shape memory ability, abnormal deformation, and peeling.
FIG. 9 shows the relationship of the transformation end time when the energization heating current of the heating control is changed. When the energization heating current is large, the transformation end time is shortened. When the SMA transformation end temperature of 62 ° C. in this example is exceeded, the heating current is automatically controlled to be cut off and self-repair is completed.
In the experiment, the heating period was set to 0.1 seconds. However, when it is desired to shorten the transformation end time, the heating current is increased, and the heating time may be determined according to accuracy.
Thus, one of the points showing the effectiveness of the present method is that the heating current and the heating time can be freely selected.
[0021]
【The invention's effect】
In the present invention, in a panel in which an SMA wire covered with an insulating film is embedded in a lattice in a composite material, the damage position of the panel is measured at any time by measuring the resistance of the SMA wire , and the time differential of the resistance is obtained to determine the damage position, etc. a judgment, flowing a pulse current to the SMA wire is detected damage, subjected to heat and resistance measurements of the SMA wire, by blocking the pulse current from the time derivative of the resistance, the heating current without being affected by such ambient temperature And having a remarkable effect that the heating time can be optimized.
Further, the present invention can prevent the progress of damage at high speed and without overheating. For this reason, loss of shape memory ability, abnormal deformation, and peeling can be suppressed, and an excellent effect of preventing fire can be obtained.
Furthermore, when the control method and the control circuit of the present invention are used, the state of SMA phase transformation can be automatically detected even when the ambient temperature, convection, or radiant heat state is unknown. Since it can be set freely according to the application, it has a wide range of use, and can be applied to all smart materials that want to transform SMA according to the purpose.
[Brief description of the drawings]
FIG. 1 is a schematic view of a smart material / composite panel in which an SMA line is embedded.
FIG. 2 shows a case in which a crack is formed in a panel embedded with an SMA wire (a), and the SMA wire of EW2 and NS3 is heated and contracted, and the width of the crack is narrowed by the phase transformation of the SMA wire (b). It is a schematic diagram.
FIG. 3 is a graph showing typical temperature-specific resistance characteristics of a Ti—Ni alloy.
FIG. 4 is a diagram showing a calculated value and a measured value of time differentiation of specific resistance.
FIG. 5 is a diagram showing a time derivative of specific resistance and a change in specific resistance.
FIG. 6 is a schematic explanatory diagram of an experiment in which a pre-crack is applied to a composite material panel, a tensile load is applied, a crack is propagated, a damage position is detected by a self-healing system, heating control is performed, and self-healing is confirmed. It is.
FIG. 7 is a schematic diagram of a control circuit according to the present embodiment.
FIG. 8 is a diagram illustrating a monitor example of time differentiation when a crack occurs.
FIG. 9 is a diagram showing the transformation end time when the heating current is changed.
[Explanation of symbols]
1. Composite panel2. 2. SMA wire Crack 4. Pre-cracking 5. Control circuit

Claims

In a composite material in which a shape memory alloy (hereinafter referred to as SMA) wire covered with intersecting insulating films is embedded in a grid, the damage position of the panel is determined based on the initial resistance value of the SMA wire. In the panel, the damage position is determined by comparing the resistance values, determining the time derivative, and setting the time derivative allowable limit within 0.9% of the resistance time derivative value. For detecting the damage position of a shape memory alloy.

Optionally measuring the change in resistance of the SMA wire in the damaged position detection process, before the resistance value at the time of measurement as a reference to compare the resistance value calculated time derivative of the resistance calculation, rhombohedral phase of SMA than the time derivative allowable limit (hereinafter 2. The method for detecting a damage position of a shape memory alloy in a panel according to claim 1, wherein the damage position of the smart composite material is confirmed regardless of the presence or absence of (R phase).

In a panel in which SMA wires covered with intersecting insulation films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time based on the initial resistance value of the SMA wire. comparing the time differential allowed limit seek time differential, a determination is more damaged position to within 0.9% of the time differential value of the resistor, the SMA wire is detected damage, flowing pulse current A method of self-healing a panel, comprising heating an SMA wire to repair damage.

Optionally measuring the change in resistance of the SMA wire in the damaged position detection process, before the resistance value at the time of measurement as a reference to compare the resistance value calculated time derivative of the resistance calculation, the presence of R-phase of the SMA from the time derivative allowable limit 4. The panel self-healing method according to claim 3, wherein the damage position of the smart composite material is confirmed regardless.

In a panel in which SMA wires covered with intersecting insulation films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time based on the initial resistance value of the SMA wire. comparing the time differential allowed limit seek time differential, a determination is more damaged position to within 0.9% of the time differential value of the resistance, by applying a pulse current to the SMA wire detects damage SMA wire is heated at the same time and resistance is measured at the same time. The resistance value is compared with the resistance value at the time of the previous measurement to obtain the time derivative of the resistance. A self-sensing heating control method for a shape memory alloy in a panel, characterized by determining termination.

In a panel in which SMA wires covered with intersecting insulation films are embedded in a lattice in a composite material, the damage position of the panel is measured from time to time based on the initial resistance value of the SMA wire , and the resistance value comparing the time differential allowed limit seek time differential, a determination is more damaged position to within 0.9% of the time differential value of the resistance, by applying a pulse current to the SMA wire detects damage performs a fast heating of the SMA wire, and performs resistance measurements of the SMA wire simultaneously compares the previous resistance value with respect to the resistance value of the measurement determined time derivative of the resistance, time differential defines a ± 60% of the time differential value When the resistance change of the SMA wire enters the range of the time differentiation specified value, the repair of the damage by heating is terminated without overheating by cutting off the pulse current when the change in resistance of the SMA wire enters the range of the time differential specified value. repair Law.

SMA wire is heated and resistance is measured at the same time. The resistance value is compared with the resistance value at the time of the previous measurement to obtain the time derivative of the resistance. The panel self-healing method according to claim 6, wherein:

During the heating process, a pulse current is passed through the SMA wire, the SMA wire is heated and the resistance is measured, the initial resistance value of the SMA wire is used as a reference, the resistance of the SMA wire is measured as needed, and the resistance value is compared to obtain the time derivative. 8. The panel self-healing method according to claim 3 , wherein the pulse current is cut off when the time differential value of the resistance exceeds a time differential regulation value.

The time differential tolerance limit of resistance is based on the initial resistance value of the SMA wire, and the resistance value of the SMA wire is measured at any time, the resistance value is compared, the time derivative of the resistance is obtained, and within 0.9% of the value A method for detecting a damage position of a shape memory alloy in a panel and a method for self-healing the panel according to any one of claims 1 to 4 and 6 to 8.

The time differential tolerance limit of resistance is based on the initial resistance value of the SMA wire, the resistance of the SMA wire is measured at any time, the resistance value is compared, the time derivative of the resistance is obtained, and within 0.5% of the value 10. A method for detecting a damage position of a shape memory alloy in a panel according to claim 9, and a method for self-repairing the panel.

The resistance time differential regulation value is to measure the resistance change of the SMA wire as needed, compare the resistance value with the resistance value at the previous measurement as a reference, find the time differential of the resistance, and make it within the range of ± 60% of that value A method for detecting a damage position of a shape memory alloy in a panel according to any one of claims 6 to 10 and a method for self-repairing the panel.

The resistance time differential regulation value is to measure the resistance change of the SMA wire as needed, compare the resistance value with the resistance value at the previous measurement as a reference, find the time differential of the resistance, and make it within the range of ± 30% of that value A method for detecting a damage position of a shape memory alloy in a panel according to any one of claims 6 to 10 and a method for self-repairing the panel.

13. The method for detecting a damage position of a shape memory alloy in a panel according to claim 1, wherein the composite material panel is formed by molding a carbon fiber-based composite material or a glass fiber-based material, and the panel. Composite panel used for self-healing methods.

14. The method for detecting a damage position of a shape memory alloy in a panel according to claim 1, wherein the insulating film is a polyimide / polyetherimide / fluorine resin made of thermoplastic resin. A composite panel used in the repair method.