Force chains based mesoscale simulation on the dynamic response of Al-PTFE granular composites

Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminum-polytetrafluoroethylene (Al-PTFE) granular composites under a low-velocity impact. A two-dimensional model followed the randomly normal distribution of real Al particles size is developed. The dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the experiments. The results indicate that, force chains behavior governed by the number and the size of agglomerated Al particles, significantly affects the impact response of the material. The failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density. A high crack area of the material is critical mechanism to arouse the initiation re-action. The damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction performance. In addition, simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of materials. It is found that smaller sized Al particle of com-posites are more preferred than its bulky material in ultimate strength. Increasing dispersed degree is facilitated to create stable force chains in samples with comparable particle number. The simulation studies provide further insights into the plastic deformation, failure mechanism, and possible energy release capacity for Al-PTFE composites, which is helpful for further design and application of reactive materials.     

在依法从严治校中加强院校正规化建设

依法从严治校,是体现现代教育思想和遵循军事教育规律的办学之道,是一种先进高效的管理模式。武警院校在调整改革中,必须始终坚持从严治警、依法从严治校,不断提高院校正规化建设水平。     

Rhetoric versus reality: Canadian defence planning in a time of austerity

As Canada's military mission in Afghanistan winds down and the country faces several years of fiscal austerity, all of Canada's major political parties are agreed that Canadian defence budgets must stay level or be cut. This comes at a time when the defence department is slated to replace the Canadian Forces’ (CF) major equipment fleets. Canada's defence establishment thus faces some critical decisions. One option is to try to maintain its expeditionary capabilities across all three services: army, navy and air force. Absent substantial new infusions of funds, however, this approach is likely to lead to an overall and largely chaotic reduction of capabilities. Another option is to make some difficult choices as to which expeditionary capabilities to maintain as part of a strategic review of Canada's future military needs. Such an option would ensure that Canada has at least some military capacities which can reliably be devoted to the most demanding international operations, while maintaining those capabilities required for domestic duties and North American defence. Pursuing this option would accord with the new North Atlantic Treaty Organization Strategic Concept and the call for “Smart Defense” within the Alliance. This article assesses the arguments for and against the option of specialising Canada's future defence capabilities and explores scenarios as to what a future CF may look like.     

Swedish–Finnish naval cooperation in the Baltic Sea: motives,prospects and challenges

Recently, Finland and Sweden decided to substantially deepen their defence cooperation and this project involves creating a bilateral standing Naval Task Group (SFNTG). The present article aims at examining the deepening naval cooperation between Finland and Sweden from a regional integration perspective, focusing on its motives, current challenges and future prospects. Driven by perceptions of common challenges and desires for cost-effectiveness, and strengthened by recent successes on sea surveillance and a combined Amphibious Task Unit, the bilateral project has considerable potential to achieve success. To fulfil its objectives, substantial legal changes in both countries are required to allow the use of force on each other’s territorial waters. To cater for the requirement of not conflicting with EU, NORDEFCO or NATO cooperations, the bilateral Task Group must operate according to NATO standards and by using English as the language in command and control. The costs of adjusting the naval units to NATO’s technical requirements are far from negligible and this issue still remains to be solved. If Finland and Sweden manage to incorporate new policies, common structures and common organisational norms among their navies, an even deeper integration, as in Belgium and the Netherlands, are conceivable.     

Mimetic and normative isomorphism in the establishment and maintenance of independent air forces

Why do countries have air forces? Organizational alternatives, such as maintaining separate air arms for the army and navy, have become quite rare. The conventional narrative advanced by advocates of independent air forces stress that the primacy of airpower in modern warfare mandates centralized control of most military aviation. In this view, political–military uncertainty has driven mimetic isomorphism – pressure on national governments to organize as others organize so as to fight or deter war just as effectively. However, working from a set of 56 countries that were politically independent within a few years of the establishment of the first ever independent air force (the Royal Air Force) in 1918, and continuing through nearly the present, there is no clear pattern of external military pressure prompting this particular reorganization. Rather, from anecdotal evidence, the cause has more likely been normative isomorphism – a professional craving to look as others look to foster political or personal legitimacy. For whatever reason, though, choices of structures tend to lead to specific choices of policies. Thus, the result suggests that defense ministries looking for more effective or less costly organizational schemas may reasonably consider alternatives to the tripartite army–navy–air force structure.     

North European security after the Ukraine conflict†

Russia’s illegal occupation and annexation of the Crimean peninsula in February–March 2014, and the country’s well-documented involvement in the separatist conflict in Eastern Ukraine, have led to a significant worsening of Russia’s relations with the West. Vladimir Putin’s move to redraw Russia’s southern borders through the use of military force and subversive measures has given rise to an uncertainty that goes well beyond the post-Soviet space. Since 2014, North Atlantic Treaty Organization (NATO) has had to reassess many aspects of its relationship with Russia. The alliance has also initiated various measures to strengthen the military security of its eastern member states, particularly the Baltic states, Poland, and Romania. Further to the North, NATO’s northernmost member – Norway – is following developments in Russia with a heightened sense of awareness. The same goes for non-aligned Sweden and Finland, which are trying to adapt to the emerging, and increasingly complex, security environment in Northern Europe.     

Global counterinsurgency and US army expansion: the case for recruiting foreign troops

Given the nature of global counterinsurgency operations, the demands of military expansion, and the need for cultural, linguistic, and regional expertise, the United States Army should evaluate the establishment of US-led foreign troop units for its evolving force structure. This article proposes the creation of an American foreign legion based upon the recruitment of US-led, ethnically homogeneous tribal force units to meet the grist mill of counterinsurgency operations. This structured approach would be more beneficial than the current reliance on a de facto American Foreign Legion, represented by private military contractors (PMCs), many of them comprised of foreigners. These PMCs carry a number of oversight, accountability, and legal risks not found in a fully integrated, and US-officered foreign legion. The British Brigade of Gurkhas, the South-West African Police Counter-Insurgency Unit (Koevoet), and the Kit Carson Scouts serve as relevant historical examples where foreign troops were used to supplement national manpower resources.     

The Dutch COIN approach: three years in Uruzgan, 2006–2009

Rarely has a military commitment led to such intense discussion in the Netherlands as the Task Force Uruzgan (TFU) mission in Afghanistan. In February 2010, the Netherlands' coalition government even collapsed after the two largest parties failed to agree on the withdrawal of Dutch troops from Afghanistan later this year. This article deals first of all with the difficult discussion over the Afghanistan mission of the TFU. The authors then subject three ISAF operations to close scrutiny. The authors provide some suggestions to help understand better this pivotal point in the execution of the whole operation and thus give a fuller picture of the Dutch counterinsurgency approach in Uruzgan.     

Squad leaders today,village leaders tomorrow: Muslim auxiliaries and tactical politics in Algeria, 1956–1962

From 1956 to 1960, the French Army developed a force of Muslim auxiliaries (supplétifs) as a major component of its strategy to combat the National Liberation Front (FLN) insurgency in Algeria. Aside from their military utility in hunting down the guerrillas in the mountains and forests, the supplétifs were instrumental in undermining FLN legitimacy in the countryside. The rapid growth and employment of the supplétif force dismantled FLN political control in the villages, undermined the enemy's unity, and critically weakened the revolutionaries' claim to represent all of Algeria's Muslims. The military and political activities of France's Muslim soldiers also projected an image of Muslim–European unity behind the French cause, and portrayed the French Army as the only legitimate political force in numerous villages. These political successes, however, were limited to the local, tactical level of revolutionary warfare, and the Army was never able to convert the supplétifs into a force of decisive, strategic political significance. They thus had little ultimate impact on the outcome of the conflict.     

NATO's Transformation Gaps: Transatlantic Differences and the War in Afghanistan

The North Atlantic Treaty Organization (NATO) has since the turn of the new century experienced a double transformation gap: between global and regionally oriented allies and between allies emulating new military practices defined by the United States and allies resisting radical change. This article takes stock of these gaps in light of a decade's worth of collective and national adjustments and in light of counter-insurgency lessons provided by Afghanistan. It argues first of all that the latter transatlantic gap is receding in importance because the United States has adjusted its transformation approach and because some European allies have significantly invested in technological, doctrinal, and organizational reform. The other transformation gap is deepening, however, pitching battle-hardened and expeditionary allies against allies focused on regional tasks of stabilization and deterrence. There is a definite potential for broad transformation, our survey of officers' opinion shows, but NATO's official approach to transformation, being broad and vague, provides neither political nor military guidance. If NATO is to move forward and bridge the gap, it must clarify the lessons of Afghanistan and embed them in its new Strategic Concept.