Последовательность разрушения слоев двуслойной балки при трехточечном нагружении

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Аннотация

В статье рассматривается хрупкое разрушение двухслойной балки в условиях трехточечного нагружения в зависимости от рассматриваемых параметров — различных пропорций толщин, модулей Юнга и прочностей обоих слоев. На основании уравнений равновесия сил и моментов выводятся зависимости положения нейтральной оси балки, ее кривизны и определяются области параметров, при которых разрушение начинается ранее в слое, к которому прилагается нагрузка, чем во внешнем противоположном нагрузке слое. 

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1. Предварительные сведения

Среди множества различных технологий проектирования, расчета и создания слоистых композитов [1; 2] активно развивается методика, основанная на технологии самораспространяющегося высокотемпературного синтеза (СВС). Возможность создавать высокопрочные, устойчивые ко внешним воздействиям слоистые материалы разичных пропорций, упругих, прочностных, геометрических, структурных характеристик [3 MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFtaca aa@3C72@ 7] нуждается в предварительном определении наиболее оптимальных их соотношений для решения возможных задач промышленности, а также для корректной трактовки результатов экспериментальных исследований создаваемых материлов.

2. Постановка задачи

Рассмотрим балку прямоугольного поперечного сечения S MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaam4uaaaa@38DB@ из двух слоев различной толщины из упругих однородных материалов в условиях трехточечного нагружения. Нижний слой, противоположный стороне приложения нагрузки P, MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiuaiaaiYcaaaa@398E@ обозначим индексом 1 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaaGymaaaa@38BE@ , а верхний слой MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ индексом 2 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaaGOmaaaa@38BF@ . Толщина слоев и их пропорции могут быть различными, но сумма толщин равна фиксированной величине толщины балки b MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamOyaaaa@38EA@ .

Направим ось x MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiEaaaa@3900@ горизонтально вдоль оси балки, а y MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamyEaaaa@3901@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFtaca aa@3C72@ ортогонально оси x MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiEaaaa@3900@ вверх по толщине. Ось z MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamOEaaaa@3902@ направлена ортогонально плоскости xy MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiEaiaadMhaaaa@39FE@ по ширине a MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamyyaaaa@38E9@ балки (рис. 1), L MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamitaaaa@38D4@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ расстояние между опорами при трехточечном нагружении, h MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiAaaaa@38F0@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ толщина нижнего слоя, bh MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamOyaiabgkHiTiaadIgaaaa@3AC4@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ толщина верхнего слоя. Технология изготовления слоистых композитов методом СВС приводит к тому, что зона разделения слоев представляет собой диффузионную прослойку толщины Δ MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeuiLdqeaaa@3969@ .

 

Рис.1. Схема двухслойной балки с диффузионной прослойкой

Fig. 1. Scheme of a two-layer beam with a diffusion layer

 

Для выбраной системы координат рассмотрим нормальные компоненты σ(x,y) MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4WdmNaaGikaiaadIhacaaISaGaamyEaiaaiMca aaa@3DDC@ упругих напряжений по сечению в точке x MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamiEaaaa@3900@ , ортогональному нейтральной оси, координата которой y 0 (x) MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamyEamaaBaaaleaacaaIWaaabeaakiaaiIcacaWG 4bGaaGykaaaa@3C53@ . E(y) MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamyraiaaiIcacaWG5bGaaGykaaaa@3B30@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ модуль Юнга, ϰ(x) MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wzaGqb a8aacqWFWpq+caaIOaGaamiEaiaaiMcaaaa@4660@ MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFuaca aa@3C73@ кривизна нейтральной оси. Изменением напряжений по координате z MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamOEaaaa@3902@ пренебрегаем. Также полагаем, что отношение расстояния между опорами к толщине балки достаточно велико, чтобы не учитывать влияние касательных компонент напряжений.

Введем три параметра двухслойности MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaaruWqHXwAIjxAaGqbaKqzGfaeaaaaaaaaa8GacaWFtaca aa@3C72@ отношение модуля Юнга нижнего слоя к верхнему γ= E 1 / E 2 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGypaiaadweadaWgaaWcbaGaaGymaaqa baGccaaIVaGaamyramaaBaaaleaacaaIYaaabeaaaaa@3E97@ , отношение толщины нижнего слоя ко всей толщине балки η=h/b MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4TdGMaaGypaiaadIgacaaIVaGaamOyaaaa@3D03@ и отношение пределов прочности на растяжение нижнего слоя к верхнему λ= σ 1 * / σ 2 * MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4UdWMaaGypaiabeo8aZnaaDaaaleaacaaIXaaa baGaaGOkaaaakiaai+cacqaHdpWCdaqhaaWcbaGaaGOmaaqaaiaaiQ caaaaaaa@4200@ .

Требуется определить область параметров двухслойности γ,η,λ MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGilaiabeE7aOjaaiYcacqaH7oaBaaa@3E76@ , в которой хрупкое разрушение будет начинаться в верхнем слое раньше, чем в нижнем.

3. Решение задачи

В силу особой жесткости получаемых СВС материалов уместно будет решать задачу в рамках гипотезы плоских сечений. Также положим, что в диффузионной прослойке упругие свойства изменяются линейно от материала 1 до материала 2, тогда

σ(x,y)=ϰ(x)E(y)( y 0 y),E(y)= E 2 ,y h+1/2Δ,b , 1/2 E 1 + E 2 + E 2 E 1 (yh) Δ ,y h1/2Δ,h+1/2Δ , E 1 ,y 0,h1/2Δ . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4WdmNaaGikaiaadIhacaaISaGaamyEaiaaiMca caaI9aWefv3ySLgznfgDOfdaryqr1ngBPrginfgDObYtUvgaiuaacq WFWpq+caaIOaGaamiEaiaaiMcacaWGfbGaaGikaiaadMhacaaIPaGa aGikaiaadMhadaWgaaWcbaGaaGimaaqabaGccqGHsislcaWG5bGaaG ykaiaaiYcacaaMe8UaamyraiaaiIcacaWG5bGaaGykaiaai2dadaGa baqaauaabaqadeaaaeaacaWGfbWaaSbaaSqaaiaaikdaaeqaaOGaaG ilaiaaysW7caWG5bGaeyicI48aaKamaeaacaWGObGaey4kaSIaaGym aiaai+cacaaIYaGaeuiLdqKaaGilaiaadkgaaiaawIcacaGLDbaaca aISaaabaGaaGymaiaai+cacaaIYaWaaeWaaeaacaWGfbWaaSbaaSqa aiaaigdaaeqaaOGaey4kaSIaamyramaaBaaaleaacaaIYaaabeaaaO GaayjkaiaawMcaaiabgUcaRmaabmaabaGaamyramaaBaaaleaacaaI YaaabeaakiabgkHiTiaadweadaWgaaWcbaGaaGymaaqabaaakiaawI cacaGLPaaadaWcaaqaaiaaiIcacaWG5bGaeyOeI0IaamiAaiaaiMca aeaacqqHuoaraaGaaGilaiaaysW7caWG5bGaeyicI48aamWaaeaaca WGObGaeyOeI0IaaGymaiaai+cacaaIYaGaeuiLdqKaaGilaiaadIga cqGHRaWkcaaIXaGaaG4laiaaikdacqqHuoaraiaawUfacaGLDbaaca aISaaabaGaamyramaaBaaaleaacaaIXaaabeaakiaaiYcacaaMe8Ua amyEaiabgIGiopaajibabaGaaGimaiaaiYcacaWGObGaeyOeI0IaaG ymaiaai+cacaaIYaGaeuiLdqeacaGLBbGaayzkaaGaaGOlaaaaaiaa wUhaaaaa@A46C@ (1)

Введем безразмерные координаты и параметры:

χ= x L ,ψ= y b ,ξ= y 0 b ,δ= Δ b ,l= L b ,p= P 2 E 2 ab = 1 2 E 2 P S . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4XdmMaaGypamaalaaabaGaamiEaaqaaiaadYea aaGaaGilaiabeI8a5jaai2dadaWcaaqaaiaadMhaaeaacaWGIbaaai aaiYcacqaH+oaEcaaI9aWaaSaaaeaacaWG5bWaaSbaaSqaaiaaicda aeqaaaGcbaGaamOyaaaacaaISaGaeqiTdqMaaGypamaalaaabaGaeu iLdqeabaGaamOyaaaacaaISaGaamiBaiaai2dadaWcaaqaaiaadYea aeaacaWGIbaaaiaaiYcacaWGWbGaaGypamaalaaabaGaamiuaaqaai aaikdacaWGfbWaaSbaaSqaaiaaikdaaeqaaOGaamyyaiaadkgaaaGa aGypamaalaaabaGaaGymaaqaaiaaikdacaWGfbWaaSbaaSqaaiaaik daaeqaaaaakmaalaaabaGaamiuaaqaaiaadofaaaGaaGOlaaaa@5F94@ (2)

Запишем систему уравнений равновесия продольных сил и моментов (здесь и далее для продольной координаты χ 0,1/2 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4XdmMaeyicI48aamWaaeaacaaIWaGaaGilaiaa igdacaaIVaGaaGOmaaGaay5waiaaw2faaaaa@40D0@ ) 0 η1/2δ γ(ξψ)dψ+ η1/2δ η+1/2δ 2(1γ)(ψη)+(1+γ)δ 2δ (ξψ)dψ+ η+1/2δ 1 (ξψ)dψ=0, MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaa8qCaeqaleaacaaIWaaabaGaeq4TdGMaeyOeI0Ia aGymaiaai+cacaaIYaGaeqiTdqganiabgUIiYdGccqaHZoWzcaaIOa GaeqOVdGNaeyOeI0IaeqiYdKNaaGykaiaadsgacqaHipqEcqGHRaWk daWdXbqabSqaaiabeE7aOjabgkHiTiaaigdacaaIVaGaaGOmaiabes 7aKbqaaiabeE7aOjabgUcaRiaaigdacaaIVaGaaGOmaiabes7aKbqd cqGHRiI8aOWaaSaaaeaacaaIYaGaaGikaiaaigdacqGHsislcqaHZo WzcaaIPaGaaGikaiabeI8a5jabgkHiTiabeE7aOjaaiMcacqGHRaWk caaIOaGaaGymaiabgUcaRiabeo7aNjaaiMcacqaH0oazaeaacaaIYa GaeqiTdqgaaiaaiIcacqaH+oaEcqGHsislcqaHipqEcaaIPaGaamiz aiabeI8a5jabgUcaRmaapehabeWcbaGaeq4TdGMaey4kaSIaaGymai aai+cacaaIYaGaeqiTdqgabaGaaGymaaqdcqGHRiI8aOGaaGikaiab e67a4jabgkHiTiabeI8a5jaaiMcacaWGKbGaeqiYdKNaaGypaiaaic dacaaISaaaaa@8EC3@

0 η1/2δ γ (ξψ) 2 dψ+ η1/2δ η+1/2δ 2(1γ)(ψη)+(1+γ)δ 2δ (ξψ) 2 dψ+ η+1/2δ 1 (ξψ) 2 dψ= plχ ϰ(χ) . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaa8qCaeqaleaacaaIWaaabaGaeq4TdGMaeyOeI0Ia aGymaiaai+cacaaIYaGaeqiTdqganiabgUIiYdGccqaHZoWzcaaIOa GaeqOVdGNaeyOeI0IaeqiYdKNaaGykamaaCaaaleqabaGaaGOmaaaa kiaadsgacqaHipqEcqGHRaWkdaWdXbqabSqaaiabeE7aOjabgkHiTi aaigdacaaIVaGaaGOmaiabes7aKbqaaiabeE7aOjabgUcaRiaaigda caaIVaGaaGOmaiabes7aKbqdcqGHRiI8aOWaaSaaaeaacaaIYaGaaG ikaiaaigdacqGHsislcqaHZoWzcaaIPaGaaGikaiabeI8a5jabgkHi TiabeE7aOjaaiMcacqGHRaWkcaaIOaGaaGymaiabgUcaRiabeo7aNj aaiMcacqaH0oazaeaacaaIYaGaeqiTdqgaaiaaiIcacqaH+oaEcqGH sislcqaHipqEcaaIPaWaaWbaaSqabeaacaaIYaaaaOGaamizaiabeI 8a5jabgUcaRmaapehabeWcbaGaeq4TdGMaey4kaSIaaGymaiaai+ca caaIYaGaeqiTdqgabaGaaGymaaqdcqGHRiI8aOGaaGikaiabe67a4j abgkHiTiabeI8a5jaaiMcadaahaaWcbeqaaiaaikdaaaGccaWGKbGa eqiYdKNaaGypamaalaaabaGaamiCaiaadYgacqaHhpWyaeaatuuDJX wAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wzaGqbaiab=b=a5laaiIca cqaHhpWycaaIPaaaaiaai6caaaa@A3A8@

Из уравнения равновесия сил получаем координату нейтральной оси

ξ= 1 2 1+ η 2 (γ1) 1+η(γ1) + 1 24 δ 2 (γ1) 1+η(γ1) . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeqOVdGNaaGypamaalaaabaGaaGymaaqaaiaaikda aaWaaSaaaeaacaaIXaGaey4kaSIaeq4TdG2aaWbaaSqabeaacaaIYa aaaOGaaGikaiabeo7aNjabgkHiTiaaigdacaaIPaaabaGaaGymaiab gUcaRiabeE7aOjaaiIcacqaHZoWzcqGHsislcaaIXaGaaGykaaaacq GHRaWkdaWcaaqaaiaaigdaaeaacaaIYaGaaGinaaaacqaH0oazdaah aaWcbeqaaiaaikdaaaGcdaWcaaqaaiaaiIcacqaHZoWzcqGHsislca aIXaGaaGykaaqaaiaaigdacqGHRaWkcqaH3oaAcaaIOaGaeq4SdCMa eyOeI0IaaGymaiaaiMcaaaGaaGOlaaaa@6049@ (3)

Рассмотрим, как расположена нейтральная ось относительно разделительной зоны. Это повлияет на вид уравнений равновесия. Случай, когда нейтральная ось совпадает с диффузионной прослойкой, имеет вид

ξ=η,η[0,1], 1 2 η 2 (γ1)+1+α 1+η(γ1) =η,α= 1 12 (γ1) δ 2 , MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeqOVdGNaaGypaiabeE7aOjaaiYcacaaMe8Uaeq4T dGMaeyicI4SaaG4waiaaicdacaaISaGaaGymaiaai2facaaISaGaaG jbVpaalaaabaGaaGymaaqaaiaaikdaaaWaaSaaaeaacqaH3oaAdaah aaWcbeqaaiaaikdaaaGccaaIOaGaeq4SdCMaeyOeI0IaaGymaiaaiM cacqGHRaWkcaaIXaGaey4kaSIaeqySdegabaGaaGymaiabgUcaRiab eE7aOjaaiIcacqaHZoWzcqGHsislcaaIXaGaaGykaaaacaaI9aGaeq 4TdGMaaGilaiaaysW7cqaHXoqycaaI9aWaaSaaaeaacaaIXaaabaGa aGymaiaaikdaaaGaaGikaiabeo7aNjabgkHiTiaaigdacaaIPaGaeq iTdq2aaWbaaSqabeaacaaIYaaaaOGaaGilaaaa@6E4B@

η= γ(α+1)α 1 (γ1) 1 1+ γ ,α1. MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4TdGMaaGypamaalaaabaWaaOaaaeaacqaHZoWz caaIOaGaeqySdeMaey4kaSIaaGymaiaaiMcacqGHsislcqaHXoqyaS qabaGccqGHsislcaaIXaaabaGaaGikaiabeo7aNjabgkHiTiaaigda caaIPaaaaiabgIKi7oaalaaabaGaaGymaaqaaiaaigdacqGHRaWkda Gcaaqaaiabeo7aNbWcbeaaaaGccaaISaGaaGjbVlabeg7aHfbbfv3y SLgzGueE0jxyaGqbaiab=PMi9iaaigdacaaIUaaaaa@5AFF@

Мы получили условие на толщину слоев относительно модулей упругости, когда нейтральная ось находится на границе раздела

η= 1 1+ γ . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4TdGMaaGypamaalaaabaGaaGymaaqaaiaaigda cqGHRaWkdaGcaaqaaiabeo7aNbWcbeaaaaGccaaIUaaaaa@3F62@ (4)

Из уравнения равновесия моментов выражаем кривизну:

ϰ(χ)= pl f(γ,η,δ) χ, MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wzaGqb a8aacqWFWpq+caaIOaGaeq4XdmMaaGykaiaai2dadaWcaaqaaiaadc hacaWGSbaabaGaamOzaiaaiIcacqaHZoWzcaaISaGaeq4TdGMaaGil aiabes7aKjaaiMcaaaGaeq4XdmMaaGilaaaa@54F8@ (5)

f(γ,η,δ)= 1 2 γ+(γ1) γ η 4 (η1) 4 1+η(γ1) + δ 2 8 (γ1) γ η 2 (η1) 2 1+η(γ1) 5 δ 4 576 (γ1) 2 1+η(γ1) . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaamOzaiaaiIcacqaHZoWzcaaISaGaeq4TdGMaaGil aiabes7aKjaaiMcacaaI9aWaaSaaaeaacaaIXaaabaGaaGOmaaaada WcaaqaamaabmaabaGaeq4SdCMaey4kaSIaaGikaiabeo7aNjabgkHi TiaaigdacaaIPaWaaeWaaeaacqaHZoWzcqaH3oaAdaahaaWcbeqaai aaisdaaaGccqGHsislcaaIOaGaeq4TdGMaeyOeI0IaaGymaiaaiMca daahaaWcbeqaaiaaisdaaaaakiaawIcacaGLPaaaaiaawIcacaGLPa aaaeaacaaIXaGaey4kaSIaeq4TdGMaaGikaiabeo7aNjabgkHiTiaa igdacaaIPaaaaiabgUcaRmaalaaabaGaeqiTdq2aaWbaaSqabeaaca aIYaaaaaGcbaGaaGioaaaadaWcaaqaaiaaiIcacqaHZoWzcqGHsisl caaIXaGaaGykamaabmaabaGaeq4SdCMaeq4TdG2aaWbaaSqabeaaca aIYaaaaOGaeyOeI0IaaGikaiabeE7aOjabgkHiTiaaigdacaaIPaWa aWbaaSqabeaacaaIYaaaaaGccaGLOaGaayzkaaaabaWaaeWaaeaaca aIXaGaey4kaSIaeq4TdGMaaGikaiabeo7aNjabgkHiTiaaigdacaaI PaaacaGLOaGaayzkaaaaaiabgkHiTmaalaaabaGaaGynaiabes7aKn aaCaaaleqabaGaaGinaaaaaOqaaiaaiwdacaaI3aGaaGOnaaaadaWc aaqaaiaaiIcacqaHZoWzcqGHsislcaaIXaGaaGykamaaCaaaleqaba GaaGOmaaaaaOqaamaabmaabaGaaGymaiabgUcaRiabeE7aOjaaiIca cqaHZoWzcqGHsislcaaIXaGaaGykaaGaayjkaiaawMcaaaaacaaIUa aaaa@95CD@

Подставляя (5) в (1), получаем

 

σ(χ,ψ)= E 2 ϰ(χ)(ξη),ψ η+1/2δ,1 , E 2 ϰ(χ) (1+γ 2 +(γ1) (ψη) δ (ξψ),ψ η1/2δ,η+1/2δ , E 2 1ϰ(χ)(ξψ),ψ 0,η1/2δ . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4WdmNaaGikaiabeE8aJjaaiYcacqaHipqEcaaI PaGaaGypamaaceaabaqbaeaabmqaaaqaaiaadweadaWgaaWcbaGaaG OmaaqabaWefv3ySLgznfgDOfdaryqr1ngBPrginfgDObYtUvgaiuaa kiab=b=a5laaiIcacqaHhpWycaaIPaGaaGikaiabe67a4jabgkHiTi abeE7aOjaaiMcacaaISaGaaGjbVlabeI8a5jabgIGiopaajadabaGa eq4TdGMaey4kaSIaaGymaiaai+cacaaIYaGaeqiTdqMaaGilaiaaig daaiaawIcacaGLDbaacaaISaaabaGaamyramaaBaaaleaacaaIYaaa beaakiab=b=a5laaiIcacqaHhpWycaaIPaWaaeWaaeaadaWcaaqaai aaiIcacaaIXaGaey4kaSIaeq4SdCgabaGaaGOmaaaacqGHRaWkcaaI OaGaeq4SdCMaeyOeI0IaaGymaiaaiMcadaWcaaqaaiaaiIcacqaHip qEcqGHsislcqaH3oaAcaaIPaaabaGaeqiTdqgaaaGaayjkaiaawMca aiaaiIcacqaH+oaEcqGHsislcqaHipqEcaaIPaGaaGilaiaaysW7cq aHipqEcqGHiiIZdaWadaqaaiabeE7aOjabgkHiTiaaigdacaaIVaGa aGOmaiabes7aKjaaiYcacqaH3oaAcqGHRaWkcaaIXaGaaG4laiaaik dacqaH0oazaiaawUfacaGLDbaacaaISaaabaGaamyramaaBaaaleaa caaIYaaabeaakiaaigdacqWFWpq+caaIOaGaeq4XdmMaaGykaiaaiI cacqaH+oaEcqGHsislcqaHipqEcaaIPaGaaGilaiaaysW7cqaHipqE cqGHiiIZdaqcsaqaaiaaicdacaaISaGaeq4TdGMaeyOeI0IaaGymai aai+cacaaIYaGaeqiTdqgacaGLBbGaayzkaaGaaGOlaaaaaiaawUha aaaa@BC31@

В силу линейного распределения, максимум будет достигнут либо на нижнем крае верхнего слоя 2

σ m2 (γ,η)= 1 8 l f 1+ η 2 (γ1) 1+η(γ1) + 1 12 δ 2 γ1 1+η(γ1) 2(η+1/2δ) P S , MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4Wdm3aaSbaaSqaaiaad2gacaaIYaaabeaakiaa iIcacqaHZoWzcaaISaGaeq4TdGMaaGykaiaai2dadaWcaaqaaiaaig daaeaacaaI4aaaamaalaaabaGaamiBaaqaaiaadAgaaaWaaeWaaeaa daWcaaqaaiaaigdacqGHRaWkcqaH3oaAdaahaaWcbeqaaiaaikdaaa GccaaIOaGaeq4SdCMaeyOeI0IaaGymaiaaiMcaaeaacaaIXaGaey4k aSIaeq4TdGMaaGikaiabeo7aNjabgkHiTiaaigdacaaIPaaaaiabgU caRmaalaaabaGaaGymaaqaaiaaigdacaaIYaaaaiabes7aKnaaCaaa leqabaGaaGOmaaaakmaalaaabaGaeq4SdCMaeyOeI0IaaGymaaqaai aaigdacqGHRaWkcqaH3oaAcaaIOaGaeq4SdCMaeyOeI0IaaGymaiaa iMcaaaGaeyOeI0IaaGOmaiaaiIcacqaH3oaAcqGHRaWkcaaIXaGaaG 4laiaaikdacqaH0oazcaaIPaaacaGLOaGaayzkaaWaaSaaaeaacaWG qbaabaGaam4uaaaacaaISaaaaa@74DA@ (6)

либо на нижнем крае нижнего слоя 1

σ m1 (γ,η)= γ 8 l f 1+ η 2 (γ1) 1+η(γ1) + 1 12 δ 2 γ1 1+η(γ1) P S . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4Wdm3aaSbaaSqaaiaad2gacaaIXaaabeaakiaa iIcacqaHZoWzcaaISaGaeq4TdGMaaGykaiaai2dadaWcaaqaaiabeo 7aNbqaaiaaiIdaaaWaaSaaaeaacaWGSbaabaGaamOzaaaadaqadaqa amaalaaabaGaaGymaiabgUcaRiabeE7aOnaaCaaaleqabaGaaGOmaa aakiaaiIcacqaHZoWzcqGHsislcaaIXaGaaGykaaqaaiaaigdacqGH RaWkcqaH3oaAcaaIOaGaeq4SdCMaeyOeI0IaaGymaiaaiMcaaaGaey 4kaSYaaSaaaeaacaaIXaaabaGaaGymaiaaikdaaaGaeqiTdq2aaWba aSqabeaacaaIYaaaaOWaaSaaaeaacqaHZoWzcqGHsislcaaIXaaaba GaaGymaiabgUcaRiabeE7aOjaaiIcacqaHZoWzcqGHsislcaaIXaGa aGykaaaaaiaawIcacaGLPaaadaWcaaqaaiaadcfaaeaacaWGtbaaai aai6caaaa@6C56@ (7)

При существенной малости толщины диффузионного слоя ( δ 10 6 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeqiTdqweeuuDJXwAKbsr4rNCHbacfaGae8NAI0Ja aGymaiaaicdadaahaaWcbeqaaiabgkHiTiaaiAdaaaaaaa@42E1@ ) мы в дальнейших выкладках пренебрежем им и будем использовать следующие равенства:

ξ= 1 2 1+ η 2 (γ1) 1+η(γ1) ,ϰ(χ)=3l 1+η(γ1) γ+(γ1) γ η 4 (η1) 4 χ P E 2 S . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeqOVdGNaaGypamaalaaabaGaaGymaaqaaiaaikda aaWaaSaaaeaacaaIXaGaey4kaSIaeq4TdG2aaWbaaSqabeaacaaIYa aaaOGaaGikaiabeo7aNjabgkHiTiaaigdacaaIPaaabaGaaGymaiab gUcaRiabeE7aOjaaiIcacqaHZoWzcqGHsislcaaIXaGaaGykaaaaca aISaGaaGjbVprr1ngBPrwtHrhAXaqeguuDJXwAKbstHrhAG8KBLbac faGae8h8dKVaaGikaiabeE8aJjaaiMcacaaI9aGaaG4maiaadYgada WcaaqaaiaaigdacqGHRaWkcqaH3oaAcaaIOaGaeq4SdCMaeyOeI0Ia aGymaiaaiMcaaeaacqaHZoWzcqGHRaWkcaaIOaGaeq4SdCMaeyOeI0 IaaGymaiaaiMcadaqadaqaaiabeo7aNjabeE7aOnaaCaaaleqabaGa aGinaaaakiabgkHiTiaaiIcacqaH3oaAcqGHsislcaaIXaGaaGykam aaCaaaleqabaGaaGinaaaaaOGaayjkaiaawMcaaaaacqaHhpWydaWc aaqaaiaadcfaaeaacaWGfbWaaSbaaSqaaiaaikdaaeqaaOGaam4uaa aacaaIUaaaaa@827E@

В этом случае максимальное напряжение в центральном сечении балки на противоположном точке приложения силы крае балки будет в верхнем слое:

σ m2 (γ,η)= 3 2 l 1η 2 γ η 2 γ+(γ1) γ η 4 (η1) 4 P S . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4Wdm3aaSbaaSqaaiaad2gacaaIYaaabeaakiaa iIcacqaHZoWzcaaISaGaeq4TdGMaaGykaiaai2dadaWcaaqaaiaaio daaeaacaaIYaaaaiaadYgadaWcaaqaamaabmaabaWaaeWaaeaacaaI XaGaeyOeI0Iaeq4TdGgacaGLOaGaayzkaaWaaWbaaSqabeaacaaIYa aaaOGaeyOeI0Iaeq4SdCMaeq4TdG2aaWbaaSqabeaacaaIYaaaaaGc caGLOaGaayzkaaaabaGaeq4SdCMaey4kaSIaaGikaiabeo7aNjabgk HiTiaaigdacaaIPaWaaeWaaeaacqaHZoWzcqaH3oaAdaahaaWcbeqa aiaaisdaaaGccqGHsislcaaIOaGaeq4TdGMaeyOeI0IaaGymaiaaiM cadaahaaWcbeqaaiaaisdaaaaakiaawIcacaGLPaaaaaWaaSaaaeaa caWGqbaabaGaam4uaaaacaaIUaaaaa@6713@

Максимальное напряжение в нижнем слое:

σ m1 (γ,η)= 3 2 lγ 1+ η 2 (γ1) γ+(γ1) γ η 4 (η1) 4 P S . MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4Wdm3aaSbaaSqaaiaad2gacaaIXaaabeaakiaa iIcacqaHZoWzcaaISaGaeq4TdGMaaGykaiaai2dadaWcaaqaaiaaio daaeaacaaIYaaaaiaadYgacqaHZoWzdaWcaaqaaiaaigdacqGHRaWk cqaH3oaAdaahaaWcbeqaaiaaikdaaaGccaaIOaGaeq4SdCMaeyOeI0 IaaGymaiaaiMcaaeaacqaHZoWzcqGHRaWkcaaIOaGaeq4SdCMaeyOe I0IaaGymaiaaiMcadaqadaqaaiabeo7aNjabeE7aOnaaCaaaleqaba GaaGinaaaakiabgkHiTiaaiIcacqaH3oaAcqGHsislcaaIXaGaaGyk amaaCaaaleqabaGaaGinaaaaaOGaayjkaiaawMcaaaaadaWcaaqaai aadcfaaeaacaWGtbaaaiaai6caaaa@651D@

Факт того, что напряжения в верхнем слое 2 достигают максимума раньше в нижнем слое 1, не означает того, что там начнется разрушение. Необходимо ввести сравнение прочностей этих слоев. Получаем условие начала разрушения в верхнем слое 2 ранее нижнего слоя 1

σ m1 σ m2 = γ(1+ η 2 (γ1) 1η 2 γ η 2 <λ= σ 1 * σ 2 * , η<ξ= 1 2 1+ η 2 (γ1) 1+η(γ1) , MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaaiqaaeaafaqaaeGabaaabaWaaSaaaeaacqaHdpWC daWgaaWcbaGaamyBaiaaigdaaeqaaaGcbaGaeq4Wdm3aaSbaaSqaai aad2gacaaIYaaabeaaaaGccaaI9aWaaSaaaeaacqaHZoWzcaaIOaGa aGymaiabgUcaRiabeE7aOnaaCaaaleqabaGaaGOmaaaakiaaiIcacq aHZoWzcqGHsislcaaIXaGaaGykaaqaamaabmaabaWaaeWaaeaacaaI XaGaeyOeI0Iaeq4TdGgacaGLOaGaayzkaaWaaWbaaSqabeaacaaIYa aaaOGaeyOeI0Iaeq4SdCMaeq4TdG2aaWbaaSqabeaacaaIYaaaaaGc caGLOaGaayzkaaaaaiaaiYdacqaH7oaBcaaI9aWaaSaaaeaacqaHdp WCdaqhaaWcbaGaaGymaaqaaiaaiQcaaaaakeaacqaHdpWCdaqhaaWc baGaaGOmaaqaaiaaiQcaaaaaaOGaaGilaaqaaiabeE7aOjaaiYdacq aH+oaEcaaI9aWaaSaaaeaacaaIXaaabaGaaGOmaaaadaWcaaqaaiaa igdacqGHRaWkcqaH3oaAdaahaaWcbeqaaiaaikdaaaGccaaIOaGaeq 4SdCMaeyOeI0IaaGymaiaaiMcaaeaacaaIXaGaey4kaSIaeq4TdGMa aGikaiabeo7aNjabgkHiTiaaigdacaaIPaaaaiaaiYcaaaaacaGL7b aaaaa@7C42@ (8)

Область параметров двухслойности γ,η MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGilaiabeE7aObaa@3C0C@ от λ MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4UdWgaaa@39B7@ , для которых максимальное напряжение достигает предела прочности на нижнем крае ранее верхнего слоя, а не нижнего, задается совокупностью неравенств, следующих из (8):

(γ+λ)(γ1) η 2 +2λη+γλ<0, (γ1) η 2 +2η1<0. MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaaiqaaeaafaqaaeGabaaabaGaaGikaiabeo7aNjab gUcaRiabeU7aSjaaiMcacaaIOaGaeq4SdCMaeyOeI0IaaGymaiaaiM cacqaH3oaAdaahaaWcbeqaaiaaikdaaaGccqGHRaWkcaaIYaGaeq4U dWMaeq4TdGMaey4kaSIaeq4SdCMaeyOeI0Iaeq4UdWMaaGipaiaaic dacaaISaaabaGaaGikaiabeo7aNjabgkHiTiaaigdacaaIPaGaeq4T dG2aaWbaaSqabeaacaaIYaaaaOGaey4kaSIaaGOmaiabeE7aOjabgk HiTiaaigdacaaI8aGaaGimaiaai6caaaaacaGL7baaaaa@60F9@ (9)

Учитывая положительность параметров, мы получаем зависимость параметров двухслойности γ,η,λ MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGilaiabeE7aOjaaiYcacqaH7oaBaaa@3E76@ , при которых максимальное напряжение достигает предела прочности на нижнем крае ранее верхнего слоя, а не нижнего:

γ(1+ η 2 (γ1)) 1η 2 γ η 2 <λ η< 1 1+ γ MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaaiqaaeaafaqaaeGabaaabaWaaSaaaeaacqaHZoWz caaIOaGaaGymaiabgUcaRiabeE7aOnaaCaaaleqabaGaaGOmaaaaki aaiIcacqaHZoWzcqGHsislcaaIXaGaaGykaiaaiMcaaeaadaqadaqa amaabmaabaGaaGymaiabgkHiTiabeE7aObGaayjkaiaawMcaamaaCa aaleqabaGaaGOmaaaakiabgkHiTiabeo7aNjabeE7aOnaaCaaaleqa baGaaGOmaaaaaOGaayjkaiaawMcaaaaacaaI8aGaeq4UdWgabaGaeq 4TdGMaaGipamaalaaabaGaaGymaaqaaiaaigdacqGHRaWkdaGcaaqa aiabeo7aNbWcbeaaaaaaaaGccaGL7baaaaa@5AE1@

4. Пример определения области параметров, соответствующих началу разрушения балки с края верхнего слоя

Рассмотрим случай γ=1 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGypaiaaigdaaaa@3B2C@ , то есть оба слоя с одинаковыми модулями Юнга. Мы определим зависимость параметров двухслойности γ,η MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGilaiabeE7aObaa@3C0C@ , при которых максимальное напряжение достигается на нижнем крае ранее верхнего слоя, а не нижнего:

1 12η <λ,0<η< 1 2 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaWaaSaaaeaacaaIXaaabaGaaGymaiabgkHiTiaaikda cqaH3oaAaaGaaGipaiabeU7aSjaaiYcacaaMe8UaaGjbVlaaicdaca aI8aGaeq4TdGMaaGipamaalaaabaGaaGymaaqaaiaaikdaaaaaaa@48A1@

σ m2 = 3 2 l 12η P S MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4Wdm3aaSbaaSqaaiaad2gacaaIYaaabeaakiaa i2dadaWcaaqaaiaaiodaaeaacaaIYaaaaiaadYgadaqadaqaaiaaig dacqGHsislcaaIYaGaeq4TdGgacaGLOaGaayzkaaWaaSaaaeaacaWG qbaabaGaam4uaaaaaaa@4641@

В результате для γ=1 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcqqaaaaaaaaGqSf 2yRbWdbeaapaGaeq4SdCMaaGypaiaaigdaaaa@3B2C@ получена область (на рис. 2. закрашена серым), в которой разрушение начнется в верхнем слое ранее, чем в нижнем:

 

Рис. 2. Зоны разрушения при γ=1

Fig. 2. Fracture zones γ=1

Выводы

Мы получили возможность заранее прогнозировать, какой слой, исходя из конкретных параметров двухслойности, запустит механизм хрупкого разрушения. Соответственно зависимость внешней нагрузки от прочности вида материала слоев стоит рассматривать в соотношениях (6) и (7).

×

Об авторах

Кирилл Анатольевич Хвостунков

Московский государственный университет имени М.В. Ломоносова

Автор, ответственный за переписку.
Email: khvostunkov@gmail.com
ORCID iD: 0000-0002-3749-0678

кандидат физико-математических наук, доцент кафедры теории пластичности

Россия, Москва

Список литературы

  1. Андреев А.Н., Немировский Ю.В. Многослойные анизотропные оболочки и пластины: Изгиб, устойчивость, колебания. Новосибирск: Наука, 2001. 288 с. URL: https://libcats.org/book/438700; https://elibrary.ru/item.asp?id=21107452. EDN: https://elibrary.ru/rtxgkt.
  2. Vasiliev V.V., Morozov E.V. Advanced Mechanics of Composite Materials and Structural Elements. Elseiver, 2013. 832 p. URL: https://books.google.ru/books?id=T1gRGmoJ9ecC&printsec=frontcover&redir_esc=y#v=onepage &q&f=false.
  3. Bazhin P.M., Konstantinov A.S., Chizhikov A.P., Pazniak A.I., Kostitsyna E.V., Prokopets A.D., Stolin A.M. Laminated cermet composite materials: The main production methods, structural features and properties (review) // Ceramics International. 2021. Vol. 47, Issue 2. P. 1513–-1525. DOI: http://doi.org/10.1016/j.ceramint.2020.08.292.
  4. Bazhina A., Konstantinov A., Chizhikov A., Bazhin P., Stolin A., Avdeeva V. Structure and mechanical characteristics of a layered composite material based on TiB/TiAl/Ti // Ceramics International. 2022. Vol. 48, Issue 10. P. 14295–14300. DOI: http://doi.org/10.1016/j.ceramint.2022.01.318.
  5. Prokopets A.D., Bazhin P.M., Konstantinov A.S., Chizhikov A.P., Antipov M.S., Avdeeva V.V. Structural features of layered composite material TiB2/TiAl/Ti6Al4V obtained by unrestricted SHS-compression // Materials Letters. 2021. Vol. 300. P. 130165. DOI: http://doi.org/10.1016/j.matlet.2021.130165.
  6. Прокопец А.Д., Константинов А.С., Чижиков А.П., Бажин П.М., Столин А.М. Закономерности формирования структуры градиентных композиционных материалов на основе МАХ-фазы Ti3AlC2 на титане // Неорганические материалы. 2020. Т. 56, № 10. С. 1145–1150. DOI: http://doi.org/10.31857/S0002337X20100127. EDN: https://elibrary.ru/xjftmu.
  7. Бажин П.М., Столин А.М., Константинов А.С., Чижиков А.П., Прокопец А.Д., Алымов М.И. Особенности строения слоистых композиционных материалов на основе боридов титана, полученных методом свободного СВС-сжатия // Доклады Академии наук. 2019. Т. 488, № 3. С. 263-–266. DOI: http://doi.org/10.31857/S0869-56524883263-266. EDN: https://elibrary.ru/cssyxo.

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© Хвостунков К.А., 2022

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