This article describes the relationship between the hardness and the strength of metal material. The strength value of metal material can be approximately calcu- lated based on the hardness value with the conversion for- mula:σs=3.28HV-221 andσb=3.55HB (applicable to metal material with HB≤175).

In this paper, the method of calculating rock shear strength value, C,f with the M robust estimate is presented, the calculating model and method are given.

Secondly. differ-ent criteria of strength value adoption were taken according to different conditions of roughness incombination with the integration of both single point method and multipoint method, calculationof single point shear strength parameters was used.

At 800℃, the samples of consolidated powders that are milled for 1 h present the maximum compressive yield strength of up to 620 MPa after sintered for 4 h at 1 250℃, which is in the vicinity of its strength value at room temperature.

The EVA/MH ( 40%/60%) blend showsexcellent rheological and mechanical properties with a balancetorque value at 12.7 N(m, a tensile strength value at 10.1MPa, and a elongation at break value at 1 150%.

The strength of SiC/Si ceramic composites which was measured by three-point bending test, was 290MPa, which attained the strength value of the ordinary reaction-bonded SiC ceramics.

The increased strength value at the lower FRT is due to the finer lath width and packet size of martensite.

The increased strength value at the lower FRT is due to the finer lath width and packet size of martensite.

The results of the as-coated 80Ni-20Cr specimens showed an adhesive-strength value of 68 MPa.

The investigation has also shown that Ti5Si3 maintains a high yield strength value up to 1200 °C.

The micromechanical behavior of these specimens under transverse loading was examined by finite element analysis using this interface bond strength value and compared with experimental observations.

Most of the ceramic materials, because of their inherent brittleness, are susceptible tothermal stress fracture. According to fracture mechanics theory, thermal stress fracture includ-es processes of flacture intiation as well as of continued crack propagation.of the two,crack propagation is more detrimental.It has been proposed that crack propagation occurs kinetically with total area of crack propagation inversly proportional to thermal shock re-sistance parameter, e. g.R≌(K_(1c)/σ_f)~2, where K_(1c) is the...

Most of the ceramic materials, because of their inherent brittleness, are susceptible tothermal stress fracture. According to fracture mechanics theory, thermal stress fracture includ-es processes of flacture intiation as well as of continued crack propagation.of the two,crack propagation is more detrimental.It has been proposed that crack propagation occurs kinetically with total area of crack propagation inversly proportional to thermal shock re-sistance parameter, e. g.R≌(K_(1c)/σ_f)~2, where K_(1c) is the critical stress intensity factor,σ_f, isthe tensile strength. In order to investigate this relationship,the critical stress intensity factor and the ther-mal shock resistance parameter of three types of alumina ceramics with different micro-structures were compared with their strength losses over a wide range of quenching tempe-rature difference (200℃<ΔT<1200℃) .Because of their structural weakening at grain boun-daries, type T-Al_2O_3 samples, which fracture almost in a completely intercrystallilae man-ner, have strength values considerably lower than those of type P-Al_2O_3 and type Ⅱ-95-Al_2O_3 samples. Nevertherless, their K_(1c) values are somewhat higher than those of type Ⅱ-95-Al_2O_3.This can be explained by energy dissipation at such grain boundaries. Their result-ing high R values coincide with the small degradation of strength in quenching. The highstrength value and low K_(1c) value of type Ⅱ-95-Al_2O_3 samples, which fracture mainlytranscrystallinely, indicate a low value of R and a consequent high strength loss in quench-ing. The relatively high K_(1c) value, together with the high strength value of type P-Al_2O_3samples produce an intermediate R value, corresponding to certain degradation of strengthin quenching. Apparently, for brittle ceramics the value of R could be the criterion for estimation ofthe relative change in strength which is a function of thermal shock.It is recommendedthat the critical stress intensity factor K_(1c), as well as the strength value σ_f, be determinedas a routine laboratory practice in the production and development of n?aterials.

Applicability of the law of mixtures in dual phase steels and its relation to microstructural features have been investigated. The results indicate under first approximation the strength of dual phase steels is linearly proportional to the percentage of martensite in the structure and is independent of the carbon content of the martensite. It is a comprehensive result of -the increase of martensitic volume fraction and microhardness of the ferrite as well as the decrease of microhardness of martensite. All of...

Applicability of the law of mixtures in dual phase steels and its relation to microstructural features have been investigated. The results indicate under first approximation the strength of dual phase steels is linearly proportional to the percentage of martensite in the structure and is independent of the carbon content of the martensite. It is a comprehensive result of -the increase of martensitic volume fraction and microhardness of the ferrite as well as the decrease of microhardness of martensite. All of these changes are due to increasing the intercritical annealing temperature. The law of mixture in dual phase steel should be modified as follows:Here γ is constant and γ<1.γ is affected by the hardness, early failure of the martensite and hardening of theferrite and so on. So it is easy to explain the deviation between strength value meas-ured by tension test and calculated with the law of mixtures in the dual phasesteels.

The article deals with the concept of rock shear strength and its meaning.It estimates,in detail,the determination methods of rock shear strength at home and abroad.According to the experiences from the work of rock shear strength and a great amount of test data,the authors con- sider that the triaxial test is the best to determine rock shear strength, and that the turning method can obtain the strength value which basically corresponds with the value obtained by the triaxial test.Internationally,...

The article deals with the concept of rock shear strength and its meaning.It estimates,in detail,the determination methods of rock shear strength at home and abroad.According to the experiences from the work of rock shear strength and a great amount of test data,the authors con- sider that the triaxial test is the best to determine rock shear strength, and that the turning method can obtain the strength value which basically corresponds with the value obtained by the triaxial test.Internationally, the method is also approved and popularized.Because limited by the equipment and technique,however,the method used frequently in China today is still the simple and double shear tests.The writers think it is better to use the simple shear test when rock shear strength is lower,and use the double one when the strength is higher.Because there is a correspondence between the τ-σ curve drawn by the simple and double shear tests and the Mohr's envelope obtained by the rock triaxial compression test,the rock shear strength obt(?)ined by using a simple or double shear equipment can meet the design demands for general engineening project.