Indentations onto crystalline silicon and copper with various indenter geometries, loading forces at room temperature belong to the widest interests in the field, because of the physical detection of structural phase ...Indentations onto crystalline silicon and copper with various indenter geometries, loading forces at room temperature belong to the widest interests in the field, because of the physical detection of structural phase transitions. By using the mathematically deduced F<sub>N</sub>h<sup>3/2 </sup>relation for conical and pyramidal indentations we have a toolbox for deciding between faked and experimental loading curves. Four printed silicon indentation loading curves (labelled with 292 K, 260 K, 240 K and 210 K) proved to be faked and not experimental. This is problematic for the AI (artificial intelligence) that will probably not be able to sort faked data out by itself but must be told to do so. High risks arise, when published faked indentation reports remain unidentified and unreported for the mechanics engineers by reading, or via AI. For example, when AI recommends a faked quality such as “no phase changes” of a technical material that is therefore used, it might break down due to an actually present low force, low transition energy phase-change. This paper thus installed a tool box for the distinction of experimental and faked loading curves of indentations. We found experimental and faked loading curves of the same research group with overall 14 authoring co-workers in three publications where valid and faked ones were next to each other and I can thus only report on the experimental ones. The comparison of Si and Cu with W at 20-fold higher physical hardness shows its enormous influence to the energies of phase transition and of their transition energies. Thus, the commonly preferred ISO14577-ASTM hardness values HISO (these violate the energy law and are simulated!) leads to almost blind characterization and use of mechanically stressed technical materials (e.g. airplanes, windmills, bridges, etc). The reasons are carefully detected and reported to disprove that the coincidence or very close coincidence of all of the published loading curves from 150 K to 298 K are constructed but not experimental. A tool-box for distinction of experimental from faked indentation loading curves (simulations must be indicated) is established in view of protecting the AI from faked data, which it might not be able by itself to sort them out, so that technical materials with wrongly attributed mechanical properties might lead to catastrophic accidents such as all of us know of. There is also the risk that false theories might lead to discourage the design of important research projects or for not getting them granted. This might for example hamper or ill-fame new low temperature indentation projects. The various hints for identifying faked claims are thus presented in great detail. The low-temperature instrumental indentations onto silicon have been faked in two consecutive publications and their reporting in the third one, so that these are not available for the calculation of activation energies. Conversely, the same research group published an indentation loading curve of copper as taken at 150 K that could be tested for its validity with the therefore created tools of validity tests. The physical algebraic calculations provided the epochal detection of two highly exothermic phase transitions of copper that created two polymorphs with negative standard energy content. This is world-wide the second case and the first one far above the 77 K of liquid nitrogen. Its existence poses completely new thoughts for physics chemistry and perhaps techniques but all of them are open and unprepared for our comprehension. The first chemical reactions might be in-situ photolysis and the phase transitions can be calculated from experimental curves. But several further reported low temperature indentation loading curves of silicon were tested for their experimental reality. And the results are compared to new analyses with genuine room temperature results. A lot is to be learned from the differences at room and low temperature.展开更多
Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with...Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.展开更多
The nanoindentation loading curves measured on fused silica were analyzed based on the theoretical relationship derived by Malzbender et al.(J Mater Res 2000, 15: 1209–1212). It was found that the ratio of the applie...The nanoindentation loading curves measured on fused silica were analyzed based on the theoretical relationship derived by Malzbender et al.(J Mater Res 2000, 15: 1209–1212). It was found that the ratio of the applied load to the square of the displacement, P/(h+h_d)~2, does not keep constant during loading segment of the nanoindentation test. Considering the existence of the indentation size effect, an empirical method for the determination of the load-independent hardness by analyzing the nanoindentation loading curves was proposed.展开更多
文摘Indentations onto crystalline silicon and copper with various indenter geometries, loading forces at room temperature belong to the widest interests in the field, because of the physical detection of structural phase transitions. By using the mathematically deduced F<sub>N</sub>h<sup>3/2 </sup>relation for conical and pyramidal indentations we have a toolbox for deciding between faked and experimental loading curves. Four printed silicon indentation loading curves (labelled with 292 K, 260 K, 240 K and 210 K) proved to be faked and not experimental. This is problematic for the AI (artificial intelligence) that will probably not be able to sort faked data out by itself but must be told to do so. High risks arise, when published faked indentation reports remain unidentified and unreported for the mechanics engineers by reading, or via AI. For example, when AI recommends a faked quality such as “no phase changes” of a technical material that is therefore used, it might break down due to an actually present low force, low transition energy phase-change. This paper thus installed a tool box for the distinction of experimental and faked loading curves of indentations. We found experimental and faked loading curves of the same research group with overall 14 authoring co-workers in three publications where valid and faked ones were next to each other and I can thus only report on the experimental ones. The comparison of Si and Cu with W at 20-fold higher physical hardness shows its enormous influence to the energies of phase transition and of their transition energies. Thus, the commonly preferred ISO14577-ASTM hardness values HISO (these violate the energy law and are simulated!) leads to almost blind characterization and use of mechanically stressed technical materials (e.g. airplanes, windmills, bridges, etc). The reasons are carefully detected and reported to disprove that the coincidence or very close coincidence of all of the published loading curves from 150 K to 298 K are constructed but not experimental. A tool-box for distinction of experimental from faked indentation loading curves (simulations must be indicated) is established in view of protecting the AI from faked data, which it might not be able by itself to sort them out, so that technical materials with wrongly attributed mechanical properties might lead to catastrophic accidents such as all of us know of. There is also the risk that false theories might lead to discourage the design of important research projects or for not getting them granted. This might for example hamper or ill-fame new low temperature indentation projects. The various hints for identifying faked claims are thus presented in great detail. The low-temperature instrumental indentations onto silicon have been faked in two consecutive publications and their reporting in the third one, so that these are not available for the calculation of activation energies. Conversely, the same research group published an indentation loading curve of copper as taken at 150 K that could be tested for its validity with the therefore created tools of validity tests. The physical algebraic calculations provided the epochal detection of two highly exothermic phase transitions of copper that created two polymorphs with negative standard energy content. This is world-wide the second case and the first one far above the 77 K of liquid nitrogen. Its existence poses completely new thoughts for physics chemistry and perhaps techniques but all of them are open and unprepared for our comprehension. The first chemical reactions might be in-situ photolysis and the phase transitions can be calculated from experimental curves. But several further reported low temperature indentation loading curves of silicon were tested for their experimental reality. And the results are compared to new analyses with genuine room temperature results. A lot is to be learned from the differences at room and low temperature.
基金supported by the National "111 Project" Foundation of China(B06024)the National Natural Science Foundation of China(11372243)+3 种基金"Zhi Gu" Innovation Program of Southern Chinathe Major InternationalJoint Research Program of China(11120101002)International Science and Technology Cooperation Program of China(2013DFG02930)partially supported by the Fundamental Research Funds for the Central Universities(NCET-12-0437)
文摘Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.
文摘The nanoindentation loading curves measured on fused silica were analyzed based on the theoretical relationship derived by Malzbender et al.(J Mater Res 2000, 15: 1209–1212). It was found that the ratio of the applied load to the square of the displacement, P/(h+h_d)~2, does not keep constant during loading segment of the nanoindentation test. Considering the existence of the indentation size effect, an empirical method for the determination of the load-independent hardness by analyzing the nanoindentation loading curves was proposed.
