Compliant

Concepts and Processes. Contemporary dosage forms are dmg dehvery systems, designed and manufactured to achieve safe and effective therapeutic responses each time the forms are used as part of an appropriate regimen. Thus, the intent of the prescriber is accompHshed when the product is used compliantly by the patient (12—14). Each dmg product involves several interrelated concepts that must be considered in its design and manufacture (15). Examples include the following ... 

Inter-ply shear is prominently featured in cord—mbber composite laminates, and may relate to delamination-induced failures. Studies utilizing experimental, analytical, and finite element tools, with specific apphcation to tires, are significant in compliant cord—mbber composites (90—95). 

Materials respond to stress by straining. Under a given stress, a stiff material (like steel) strains only slightly a floppy or compliant material (like polyethylene) strains much more. The modulus of the material describes this property, but before we can measure it, or even define it, we must define strain properly. 

Another vulnerable area of concern is the result of the design requirement for high temperature service. To accommodate the thermal growth potential, the various sections of the expander are quite compliant. As a result, piping and forces need to be kept to a minimum. 

Often, Hertz s work [27] is presented in a very simple form as the solution to the problem of a compliant spherical indentor against a rigid planar substrate. The assumption of the modeling make it clear that this solution is the same as the model of a rigid sphere pressed against a compliant planar substrate. In these cases, the contact radius a is related to the radius of the indentor R, the modulus E, and the Poisson s ratio v of the non-rigid material, and the compressive load P by... 

Lest one be lulled into a false sense that, assuming that the JKR theory properly describes particle adhesion within its regime, DeMejo et al. [56] also reported that, for soda-lime glass particles with radii less than about 5 p.m, the contact radius varied, not as the predicted but, rather, as Similar results were reported for other systems including polystyrene spheres on polyurethane [58], as shown in Fig. 2, and for glass particles having radii between about 1 and 100 p,m on a highly compliant, plasticized polyurethane substrate [59] as illustrated in Fig. 3. 

Fig. 3. Plot of the a for glass particles as a function of on a highly compliant polyurethane substrate (from ref [59]).

For the compliant sphere against a rigid substrate, the contact area is a flat circle of radius a so that... 

However, for the case of the rigid particle indenting a compliant substrate, the change in area, which arises from the stretching of the surface of the substrate, is given by the expansion in size of a spherical cap. 

Thus the Quesnel model predicts a range of power law values from 2/3 to 0.771 depending on the ratio of the elastic modulus of the particle and the substrate. The 2/3 behavior is for a compliant particle and the 0.771 is for a compliant substrate. The transition should be smooth with changes in modulus, but does not depend on the size of the particle. 

As previously discussed, the JKR theory predicts that the detachment force is independent of the Young s modulus. Yet despite that, when Gady et al. [117] measured the detachment force of polystyrene particles from two elastomeric substrates having Young s moduli of 3.8 and 320 MPa, respectively, they found that the detachment force from only the more compliant substrate agreed with the predicted value. The force needed to separate the particle from the more rigid substrate was about a factor of 20 lower. Estimates of the penetration depth revealed that the particles would penetrate into the more compliant substrate more deeply than the heights of the asperities. Thus, in that case, the spherical particle approximation would be reasonable. On the other hand, the penetration depth... 

TTie force-curve mapping technique is often referred to as force-volume mapping commercially, although sample volume is not probed unless stiff levers or compliant surfaces are used. 

We have recently been exploring this technique to evaluate the adhesive and mechanical properties of compliant polymers in the form of a nanoscale JKR test. The force and stiffness data from a force-displacement curve can be plotted simultaneously (Fig. 13). For these contacts, the stiffness response appears to follow the true contact stiffness, and the curve was fit (see [70]) to a JKR model. Both the surface energy and modulus can be determined from the curve. Using JKR analyses, the maximum pull off force, surface energy and tip radius are... 

After some early uncertainty in the literature about the nature of the pressure sensitive bond, Dahlquist [5,6] related modulus data to tack-temperature studies and observed that the compression modulus of the adhesive had to be less than about 3 X 10 dyne/cm (3 x lO Pa) before any adhesive tack was observed. This was explained as the highest modulus that still allowed the adhesive to be sufficiently compliant to wet out or come into molecular contact with the substrate and form dispersive bonds. As other investigators [7-9] accepted this requirement it was termed the Dahlquist Criterion . 

Besides the higher volume pressure sensitive adhesives discussed above, the industry also uses other synthetic elastomers as the base component for PSA formulation. Most of these elastomers require some form of tackification to make the materials tacky. However, a few materials are low enough in Tg and sufficiently compliant to be useful without requiring compounding with tackifiers. 

Although sol-gel treatments are still being developed, their performance is very promising. They have potential to be an environmentally compliant surface treatment for both original manufacture and repair. In some applications, they may eliminate the need for separate primers. 

We believe that the explanation of results is very important. Getting results that are below the detection limit or far below any PELs or action levels will sometimes go unreported or be given very little attention. We believe that any number, even zero, is well worth discussing with anyone voicing a health concern. Posting numbers and not discussing results that are below PELs may be a compliant practice, but we believe that getting to a personal level is a much better practice [2]. 

Many organizations will not be reaching for ISO/TS 16949 without having put in place either an ISO 9000 compliant quality system or a quality systems that meets QS-9000, VDA 6.1, AVSQ 94, or EAQF 94. The few that may be motivated to use ISO/TS 16949 1999 rather than wait for ISO 16949 2001 should start out by adopting the process approach and resist any temptation to build an element-based quality system ... 

The existing quality system requirements do have some of the above requirements but it is ISO/TS 16949 in which the full impact of their relationship is evident. It follows therefore that in making the transition from your existing system to an ISO/TS 16949 compliant system, the first step is to establish the extent to which your existing system possesses these linkages and feedback loops - a sort of coherence check to verify your system is not just a bolt-on extra. 

Having designed the additional processes, you need to examine existing processes and establish the extent to which they are compliant with the relevant requirements of ISO/TS 16949. Remember that the requirements are a framework. They are not exhaustive. Your processes should possess characteristics that are compliant but are likely to possess many other characteristics that are not addressed by the requirements. 

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