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Short fiber/polymer composites (SFPCs) are increasingly applied in the field of high‐temperature structures. Its reliability at high temperatures has always been the core issue concerned by researchers. Here, utilizing the Force–Heat Equivalence Energy Density Principle, we developed a physically based model of temperature‐dependent ultimate tensile strength (TDUTS) for SFPCs. This model quantitatively considers the evolution of residual thermal stress, interface, fiber, and matrix performance as temperature increases. Meanwhile, the influence of fiber agglomeration frequently observed in composites and fiber orientation and length distribution is taken into account in the proposed model. The model predictions over a wide temperature range are validated against the experimental data available from the literature, indicating its reasonability and accuracy. The comparison with Kelly–Tyson model and Li's model is also performed. Additionally, the quantitative effects of the fiber agglomeration and interfacial shear strength on the TDUTS are discussed in detail. The present research not only provides an accurate and feasible approach to estimate the TDUTS of SFPCs, but also offers some helpful insights for the fabrication and design of such composites. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a temperature‐dependent model for predicting the tensile strength of 2D woven fiber reinforced ceramic matrix composites. The model takes into account the combined effects of temperature, temperature‐dependent residual thermal stress, temperature‐dependent matrix strength, and fibers strength on the tensile strength of composites. To verify the model, the tensile strengths of 2D woven fiber reinforced ceramic matrix composites available are predicted at different temperatures. The model predictions agree well with the experimental data. This work could provide a practical technical means for predicting the temperature‐dependent tensile strength of 2D woven fiber reinforced ceramic matrix composites and uncovering the dominated mechanisms leading to the change of tensile strength and their evolution with temperature. [ABSTRACT FROM AUTHOR]

In this study, a temperature-dependent longitudinal tensile strength model for short-fiber-reinforced polymer composites (SFRPCs) is established based on the sensitivities of thermal-physical properties of polymer materials to temperature and our previous work. The effects of temperature, fiber orientation distribution, fiber length distribution and residual thermal stress are considered in this model. The theoretical model is verified by comparison with tensile strength of glass SFRPCs at different temperatures. Good agreement between the model predictions and experimental results is obtained, which indicates the reasonability of the proposed models. Furthermore, the comparisons between the present models and the classical models are discussed, and the influencing factors analysis for SFRPCs is also conducted in detail. This study can not only provide a potential convenient means for predicting the temperature-dependent tensile strength of SFRPCs, but also offer useful suggestions for the material evaluation, strengthening and design. [ABSTRACT FROM AUTHOR]

• Temperature-dependent yield strength model was established for CNT/metal composites. • Variation with temperature of the contribution of each mechanism is firstly made. • Suggestions to improve the temperature-dependent yield strength are provided. • The good agreement between theory and experimental results is obtained. Strengthening mechanisms in CNT/metal composites are significant guidelines on composites design. However, the strengthening mechanisms at high temperatures have few been reported. In this work, the evolution of four common strengthening mechanisms in CNT/metal composites, including load transfer strengthening, grain refinement strengthening, enhanced dislocation density strengthening and Orowan strengthening, with temperature was investigated by our developed theoretical models. Then by considering those temperature dependent strengthening mechanisms, a temperature dependent yield strength model for CNT/metal composites was established. Further, the effects of residual thermal stress and quicker softening of matrix on the temperature dependent yield strength of composites were also taken into account. Good agreement is obtained between the model predictions and available experimental results. This study contributes a simple method to predict the yield strength for CNT/metal composites over a wide range of temperatures. In addition, the contribution of each strengthening mechanism to the yield strength of composites at different temperatures was extensively discussed. Some useful suggestions for the design of new CNT/metal composites with high yield strength at elevated temperatures were provided. [ABSTRACT FROM AUTHOR]

In this work, we proposed a temperature-dependent first matrix cracking stress model for cross-ply fiber reinforced ceramic-matrix composites (FRCMCs) first. It takes into account of the effects of interfacial shear stress and residual thermal stress as well as their evolution with temperature. Moreover, in order to characterize the effect of temperature on fracture strength, we defined the critical strain energy density associated with composites fracture, by which and the force-heat equivalence energy density principle, the temperature-dependent fracture strength model for cross-ply FRCMCs was established. The models' predictions of first matrix cracking stress and fracture strength at different temperatures are in good agreement with experimental results available. This study not only advances our in-depth understanding of the quantitative relationship between temperature and mechanical properties of cross-ply FRCMCs, but also offers a powerful tool to predict the temperature-dependent first matrix cracking stress and fracture strength. [ABSTRACT FROM AUTHOR]

Abstract In this study, the stress distribution of fiber axial stress and interfacial shear stress in fiber reinforced polymer (FRP) composites at different temperatures was derived as a function of fiber axial position. The maximum shear stress criterion was extended to be temperature dependent. Based on the extended criterion, the temperature dependent fiber debonding length of FRP composites was predicted, which is indirectly verified by other scholar's experimental study. Then, by introducing the maximum fiber axial stress transferred from the matrix to fiber by their interface including the effect of partial interfacial debonding, we modified the law of mixtures, and finally established the temperature dependent tensile strength model for FRP composites. The model considers the combined effects of temperature, constituents' properties, interfacial properties and residual thermal stress. Reasonable agreement is obtained between the model predictions and available temperature dependent tensile strength of FRP composites. Additionally, the influencing factors analysis for FRP composites is performed in detail. This work provides some important insights on the strength control mechanisms of FRP composites at different temperatures, which are beneficial to the material evaluation, strengthening, and optimization. [ABSTRACT FROM AUTHOR]

• Temperature-dependent ultimate tensile strength model was established for short fiber reinforced metal matrix composites. • Variation with temperature of the contribution of different mechanisms are firstly made. • Suggestions to improve the temperature-dependent ultimate tensile strength are provided. • The good agreement between theory and experimental results is obtained. In this paper, considering the combined influences of fiber strength and various strengthening mechanisms including load transmitting, dispersion strengthening, residual thermal stress and dislocation strengthening, and their evolution with temperature, a temperature dependent ultimate tensile strength theoretical model of short fiber reinforced metal matrix composites is established. The model is confirmed by comparing with the available experimental results of six different short fiber reinforced metal matrix composites. Then, based on the model we developed, the contribution of various strengthening mechanisms to the ultimate tensile strength of the composites with the evolution of temperature is analyzed. Besides, the quantitative influences of Young's modulus of fiber and matrix on the ultimate tensile strength evolution with temperature are discussed. Several opinions on the design of short fiber reinforced metal matrix composites are put forward, especially at high temperatures. [ABSTRACT FROM AUTHOR]