Abstract: In a companion paper in this conference  an experimental study is presented that deals with
measuring fracture properties and obtaining 3D images of the particle structure in heterogeneous
materials as mortars and concrete. The fracture mechanisms observed in the tests are modelled with
a 3D lattice model. The heterogeneity of the model is directly implemented from the 3D images
obtained in a CT-scanner. With this method realistic crack patterns can be obtained.
Abstract: In the adhesive postinstalled method, headed anchor is anchored into concrete by means of
a high strength epoxy resin adhesive. To measure the concrete compressive strength, the metal anchor
is “pulled” from the concrete. There occur four types of failure when the metal anchor is pulled out.
This paper introduces the rationale of the adhesive postinstalled method to estimate the in-place
concrete strength. The embedment depth and the diameter of the reaction ring are specified by
experimental phenomenon and theoretical analysis.
Abstract: This paper deals with the transition from a localized damage state to crack formation. Several
attempts have already been made in this field. Our approach is in the continuity of studies where
thermodynamic considerations lead to the definition of an equivalent crack concept. The main idea consists
in replacing a damaged localized zone by a crack in order to recover the same amount of dissipated energy.
On the one hand, a nonlocal model is used to modelize accurately localized damage. On the other hand, an
elastic model which authorizes the formation of a crack described by a cohesive zone model is used. This
cohesive zone model is defined thermodynamically in order to be in concordance with the damage model.
The method allows obtaining the cohesive zone model traction curve from the knowledge of the nonlocal
damage model solution. The numerical implementation is done using a Lagrangian multiplier that ensures
the energetic equivalence between both models.
Abstract: The present paper investigates specific sustained crushing stress (SSCS) of various
composite laminate designs and stiffened boxes under axial crushing test. In this regard, an
optimum composite crash box design is sought by studying the effect of laminate design and
stiffeners on SSCS. Crash boxes were fabricated from carbon/epoxy twill-weave fabrics of 4,
4 and [0,45]2. The progressive failure with three distinct crushing modes of transverse shearing,
lamina bending and brittle fracture was observed for three laminate designs. Two new assembled
composite boxes were made from channels and V-shape stiffener and tested in quasi-static
condition. Adhesive bonding was used in joining the channelled and stiffened boxes. Measured
amount of SSCS for all models were compared to find an optimum crash box. It was found SSCS
increases with increasing proportion of 0° plies in the laminate.
Abstract: Ti-51.45at.%Ni thin films were deposited onto copper substrates by magnetron sputtering.
The copper substrates were pre-punched into dog-bone specimens with 4.5mm×30mm(gauge portion)
×35µm( thickness). The substrate temperature was about 673K. The thin films were about 20µm thick.
The as-deposited films were first solution treated at 1073K for 1h, and then aged at 773K for 30min.
The grain size was estimated to be 1.5µm from scanning electron microscopy micrographs. Tensile
tests were carried out on CSS-44100 electron universal test-machine. The strain rate was 1.1×10-4 s-1.
The stress-strain curves of the free-standing film were obtained from the experimental stress-strain
curves of copper substrate together with the thin film adherent to the substrate compared with the
curves of copper substrate without film. The Hall-Patch coefficient was calculated, k=205Mpa.µm1/2.
It seems that the Hall-Patch coefficient decreases with increasing film thickness. The experimental
results showed that a series of parallel cracks grew in a concerted fashion across the thin film and the
cracks were equally spaced. The cracks were more closely spaced if the film stress was increased. The
fracture toughness of the film was estimated, c KΙ =0.96MPa·m1/2. Therefore, the minimum crack
spacing is predicted by the film stress given.
Abstract: Steel reinforced concrete (SRC) structure is a kind of building structure with excellent
mechanical performance, but the theory of crack width is not very clear. In recent years, the fracture
energy is more and more applied to research concrete materials, which has opened up a new field for
concrete materials modeling. In this paper, crack width model for SRC structure based on fracture
energy concept is put forward. A uniaxial tension model is employed in the analysis for
simplification. On the ground of the stress equilibrium as well as the relation among relative slip, steel
strain and concrete strain, the basic equations are derived. By introducing the interfacial nonlinear
bond stress versus slip constitutive relation between embedded steel and concrete, the analytical
solution for distribution of slip along the interface is obtained. And based on this result, the influence
of the interfacial bond-slip on tension stiffening of the steel is considered. The displacements of steel
and concrete at the crack face under different load levels are computed and analyzed respectively.
Finally according to the principle of work and power as well as the fracture energy concept of plain
concrete, expression for fracture energy of SRC structures is obtained, and the relation of crack width
and concrete fracture energy is established. The comparison shows that the fracture energy based on
the model agrees with the test results well.
Abstract: Based on tests under low cyclic reversed horizontal loading, damage behaviors of steel
reinforced high strength and high performance concrete (SRHSHPC) frame columns are analyzed.
The strength attenuation that considered as damage variable is figured out, and the influence of axial
compression ratio, shear span ratio, stirrup ratio and concrete strength on the strength attenuation is
discussed. The accumulative damage model, which can reveal the effect of cyclic loading and
maximum deformation, is established for the SRHSHPC frame columns. The different phases of
damage growth and their features for the SRHSHPC frame columns are analyzed, and the relation of
damage and displacement is ascertained. Furthermore, the influence of axial compression ratio, shear
span ratio, stirrup ratio and concrete strength on the damage development is also discussed. The
results show that the damage model could give a rational description for damaging process of the
SRHSHPC frame columns.
Abstract: A mechanical model of the visco-elastic compressible material is established in order to
investigate the viscous effect in dynamic growing crack-tip field. The constitutive equations on the
visco-elastic compressible material are deducted. Through asymptotic analysis, it is shown that in
the stable creep growing stage, the elastic-deformation and the visco-deformation are equally
dominant in the near-tip field, as 1 ( 1) n r− − . The asymptotic solutions of separative variable in the
crack-tip field are aslo obtained. According to numerical calculation, the curves of stress, stain and
displacement are given. The results indicate that the near-tip fields are mainly governed by the
creep exponent n and Mach number M ; the stress fields of mode I and mode II is slightly
affected by the elastic compressible deformation; the strain and displacement fields of mode I are
deeply affected by the elastic compressible deformation. However, the strain and displacement
fields of mode II are less affected by the elastic compressible deformation. The asymptotic solutions
of dynamic growing crack-tip field gained here can conveniently degenerate the incompressible
case, when the Poisson ratio 0.5 ν→ , named as HR field. The conclusions can provide the
references for further studying the dynamic growing crack-tip field in compressible material.
Abstract: In mechanical engineering, circular hole is used widely in structure design. When the
structure is overloaded or the load is changed regularly, cracks emerge and spread. Based on the
former study of dynamic stress concentration problem of SH wave by a crack originating at a
circular hole edge, in this paper, the method of Green’s function is used to investigate the problem
of dynamic stress intensity problem of double linear cracks near a circular hole impacted by
incident SH-wave. The train of thought for this problem is that: Firstly, a Green’s function is
constructed for the problem, which is a fundamental solution of displacement field for an elastic
space possessing a circular hole and a linear crack while bearing out-of-plane harmonic line source
force at any point; Secondly, in terms of the solution of SH-wave’s scattering by an elastic space
with a circular hole and a linear crack, anti-plane stresses which are the same in quantity but
opposite in direction to those mentioned before, are loaded at the region where the second crack is
in existent actually, we called this process “crack-division”; Finally, the expressions of the
dynamic stress intensity factor(DSIF) of the cracks are given when the circular hole and double
linear crack exist at the same time. Then, by using the expressions, an example was provided to
show the effect of circular hole and cracks on the dynamic stress intensity factor of the cracks.
Abstract: An anti-fatigued criterion of annularly breached shaft on mechanical design has been put
forward, and the main factors that affect fatigue life of shaft are discussed. The interrelation of the
main factors and the framework is founded. A new assessment method to fatigue life of shaft has been
put forward according to Corten-Dolan’s theory modified Miner's rule. The effect of supporting
conditions to fatigue life of shaft is discussed and the influencing parameters are obtained. The results
show that the fatigue life of broad support in two sides is longer than that of narrow support in two
sides. The results will establish the base of anti-fatigue design of shaft.