Institute of Technical and Professional StudiesInstitute of Technical and Professional Studies (ITPS)http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/222024-03-29T13:07:49Z2024-03-29T13:07:49ZRobotic-Assisted Measurement of Fabrics for the Characterization of the Shear Tension CouplingRogers, Langat K.Emmanuel, De LuyckerFarid, NoureddineMicky, Rakotondrabehttp://repository.dkut.ac.ke:8080/xmlui/handle/123456789/79952023-05-31T07:51:59Z2022-07-01T00:00:00ZRobotic-Assisted Measurement of Fabrics for the Characterization of the Shear Tension Coupling
Rogers, Langat K.; Emmanuel, De Luycker; Farid, Noureddine; Micky, Rakotondrabe
Industrial use of composite materials requires an increasingly advanced knowledge of technical textiles’ mechanical properties to control the manufacturing process and guarantee the performances of the finished products. Among the qualities that influence greatly the shaping process, the
shear deformability is key for the forming of complex composite parts with double curves geometries.
On the other hand, the stiffening of the behavior as the shearing rise is responsible for the occurrence
of the wrinkling defect. This shearing behavior of the textile reinforcement is difficult to determine
because it is non-linear and it coexists with a tensile stiffness of the fibers that is several orders of
magnitude higher. Furthermore, shear and tension are coupled due to the weaving of the textiles.
Now, few experimental methods have been proposed to measure the tension behavior of fabric as a
function of its shear level because dedicated devices are needed for this investigation, capturing the
shear-tension coupled behavior of fabric is then a difficult task. This paper deals with the robotization of the fabric shear-tension effect characterization. A KUKA robot associated with a force/torque
sensor is utilized, taking advantage of its benefits in the ability to control the state of yarn tensions
during shear tests while keeping track of the desired trajectory as enabled by the hybrid position-force
control feature. This ensures precise positioning of a sample fabric and accurate contact forces. An
anisotropic hyperelastic constitutive model for fabrics, based on the continuum theory of mechanics
that takes into account the shear-tension coupling effect was formulated analytically and numerically
simulated using Matlab software. An experimental test was then implemented to validate the proposed
model. The results from a uni-axial tensile test and shear test under constant uni-axial tensile loading
were obtained and analyzed to characterize the test sample. The model parameter identification was
performed and presented in detail.
2022-07-01T00:00:00ZDetermination of the Extent of Usage of Timber as a Construction Material in Kirinyaga County (Kenya)Muthike, James M.Kanali, ChristopherKabubo, C. K.http://repository.dkut.ac.ke:8080/xmlui/handle/123456789/58822022-06-30T08:47:22Z2022-04-03T00:00:00ZDetermination of the Extent of Usage of Timber as a Construction Material in Kirinyaga County (Kenya)
Muthike, James M.; Kanali, Christopher; Kabubo, C. K.
Worldwide it has been established that demand of construction timber far outstrips supply. Kirinyaga County has not been an exemption to this phenomenon. The demand of construction timber persists in the County and especially the hardwood species, the problem of demand outstripping supply informed the decision to carry out this study. The objective of this study was therefore to determine the extent of usage of timber as a construction material in Kirinyaga County. In order to achieve the objective, descriptive cross –sectional research design was used.
Data was collected through careful observation and documentation to determine the frequency with which timber was used in comparison to other building materials such as steel. Different aspects of timber such as timber category and types were analyzed. The results show that there was no evidence of availability of bulk volumes of hardwood timber enough for construction purposes save for small quantities which probably entered the market through theft from government forests. Larger sections of timber could also not be traced. The most available timber sections ranged between 150mm in width and 12.5mm in depth. It was also evident that the longest lengths were utmost 3600mm. Some timber samples contained moisture contents of up to 104.3% (dry basis) hence confirming the view that due to demand, timber is being used as fast as it is converted due to a higher demand. This is an indication that most of the times construction timber is used in its green state.
To counter the shortage of timber in the county and the country at large, there should be a sustained and deliberate effort to increase
tree cover to around 10% which is in line with the country’s economic blueprint of the Vision 2030.
2022-04-03T00:00:00Z