## 5 Conclusions  
The sandstone specimens subjected to different temperatures were cyclically impacted by an SHPB test equipment. The physical and mechanical behaviors of sandstone were analyzed from the perspectives of mineral composition, stress-strain, and energy, and the conclusions are as follows.  
(1) With an increase in temperature, the peak stress of sandstone shows a downward trend in the first impact. The peak strength of sandstone specimens at 200 \({}^{\circ}\)C and 600 \({}^{\circ}\)C decreases significantly, and the peak strain of sandstone specimens at 200 \({}^{\circ}\)C decreases significantly. The sandstone treated at 400 \({}^{\circ}\)C and 600 \({}^{\circ}\)C show plastic characteristics significantly and the peak strain increases. However, the sandstone specimens at 800 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C are seriously brittle and the peak strain decreases significantly.  
(2) Under the cyclic impact loading, the sandstone specimens were completely destroyed after two to three times of impact. Most sandstone specimens showed obvious brittleness in the second impact. The compaction and elastic stages were obviously shortened and the initial elastic modulus significantly increased. Compared with the early impact, the third impact compaction and elastic stages increased significantly, showing the obvious plastic characteristics.  
(3) From energy analysis, when the impact velocity increases, the incident energy also increases gradually and is approximately linearly distributed. The peak stress increases with the transmitted energy. When T \(\leq\) 600 \({}^{\circ}\)C, the energy dissipated ratio of the first impact is greater than that of the second impact. At the first impact, the dissipation energy of sandstone decreased sharply at 800 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C. Changes in energy also reflect the damage in sandstones.  
(4) From analysis of DIC results in the first impact in the initial stage of loading, when the strain field in the vertical direction is at 25 \({}^{\circ}\)C and 200 \({}^{\circ}\)C, the average tensile and compressive strains of the specimen are small. When T = 200 \({}^{\circ}\)C and 400 \({}^{\circ}\)C, the tensile strain distribution area of the sandstone increases significantly in the middle of loading. When T = 600 \({}^{\circ}\)C, the tensile strain value of the sandstone is greater than that of the sandstone at other temperature sections. When T = 800 \({}^{\circ}\)C and 1000 \({}^{\circ}\)C, the initial internal damage of sandstone is serious and the stress of sandstone changes little. Therefore, the strength and strain are very small.  
Conceptualization, Q.C. and H.L.; methodology, H.L.; software, X.M. and Q.C.; vali-dation, X.M.; formal analysis, X.M.; investigation, X.M.; resources, H.L.; data curation, Q.C.; writing--original draft preparation, Q.C.; writing--review and editing, H.L. and Q.C.; visualization, Q.C.; supervision, H.L.; project administration, H.L.; funding acqui-sition, H.L. All authors have read and agreed to the published version of the manuscript.  
This work was financially supported by the Ningxia Natural Science Foundation of China (No.2020 AAC03045); Ningxia Key Research and Development Program of China (Grant No. 2021 BEG03022); Outstanding Young Teachers Training Foundation of Ningxia of China (NGY2020054); West Light Foundation of The Chinese Academy of Sciences (XAB2021 YW14); Ningxia Outstanding Talent Support Program Project of China (Grant No. TJGC2019001), and these supports are gratefully acknowledged.  
Not applicable.  
The data used to support the findings of this study are available from the corresponding author upon request.  
The authors declare no conflict of interest.